tag:blogger.com,1999:blog-21887318777071088112024-02-06T18:24:12.365-08:00 Pawn of the Pumice Castle<br>
<br>
A freshly fallen particle making his way <br> through the cycle of life and erosionMalcolm V Lhttp://www.blogger.com/profile/00126268490488546890noreply@blogger.comBlogger35125tag:blogger.com,1999:blog-2188731877707108811.post-44877202689178868472011-06-30T09:33:00.000-07:002011-06-30T09:33:34.700-07:00Field photo Set #3<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhOHM62MPAkooa8WCM0wLRUEx8q6jo7LSK_rzFdWc1WS398pWGNIGLzgb9bSv46w0BIwNOSTswS3S8jFDzJJKfQPqHDG8AUdoyPW5eY8tuaqVDYR6SZqrnekUTenFX1TSni2QoW2EsFyrQ/s1600/Picture+001.jpg" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhOHM62MPAkooa8WCM0wLRUEx8q6jo7LSK_rzFdWc1WS398pWGNIGLzgb9bSv46w0BIwNOSTswS3S8jFDzJJKfQPqHDG8AUdoyPW5eY8tuaqVDYR6SZqrnekUTenFX1TSni2QoW2EsFyrQ/s400/Picture+001.jpg" width="213" /></a>The newest pair of field photos are quite local to me, as they are a slice of glaciomarine layer cake left over from the last waxing of the Cordilleran ice sheet, specifically the <a href="http://en.wikipedia.org/wiki/Last_glacial_period#Wisconsin_glaciation.2C_in_North_America">Wisconsonian</a>. The following pair show exposures of a glaciomarine clay unit sandwiched in-between granite bodies and Holocene soil & sediment, found within North Vancouver's uplands. What you'll see are portions of the <a href="http://dsp-psd.pwgsc.gc.ca/Collection-R/GSC-CGC/M44-2000/M44-2000-A21E.pdf">Capilano Sediments member</a> of the Sumas Drift group formed in the Quaternary.<br />
<br />
The first photo (at right) is a classic exposure within the <a href="http://www.capbridge.com/">Capilano Canyon park & suspension bridge</a> (49° 21.470'N 123° 06.698'W). You'll notice the beige coloring of clay that is packed into mud; this unit is quite distinct from surrounding Holocene soil, the greenery, and the granodiorite bedrock. It has a very smooth consistency, and upon scrutiny has micro-level faults from minor stresses placed on it. The layer dips a good 10-12º to the SE, with a NE-SW strike.<br />
<br />
The foliage around the site is quite dense, even in the winter. Biomass detritus litters the photo, which was taken in the late winter months. This Pleistocene marine clay was formed at the front of valley glacier lobes stemming from the <a href="http://en.wikipedia.org/wiki/Cordilleran_Ice_Sheet">Cordilleran ice sheet</a>. The continental slope at the front was relatively high, so deep sea marine deposition was not dozens of kilometers from the glacial terminus, but rather a few kilometers. Post-Pleistocene isostatic rebound was quick in the region, and it elevated this layer to at least 50m asl, and in some areas up to a few hundred meters. Post Eocene tectonic uplift of the coast mountains caused the northern edge of these types of sedimentary units to be gently warped upwards to the north and draped over the lower slopes of the older rocks of the north shore mountains. <br />
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj2MaV7jroCji0AEfVisgwKjsS6AbOWhzVsut1f84SjKGO9xHzzOGxSt5vJ9xKcz8Rub2O4PeCA-wRqU0JsL5JGgHop0Vw4Tl9dMwL6J1Lw8s2D-UwJ_VQSorNhgKhR9ZcWWCGuq3hF5uc/s1600/Picture+002.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="353" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj2MaV7jroCji0AEfVisgwKjsS6AbOWhzVsut1f84SjKGO9xHzzOGxSt5vJ9xKcz8Rub2O4PeCA-wRqU0JsL5JGgHop0Vw4Tl9dMwL6J1Lw8s2D-UwJ_VQSorNhgKhR9ZcWWCGuq3hF5uc/s640/Picture+002.jpg" width="535" /></a></div>This exposure of the same member is found along the <a href="http://www.vancouvertrails.com/trails/lynn-peak/">Lynn Peak trail</a> (49° 21.735'N 123° 01.519'W), about a quarter of the way up, roughly 300m asl. This portion is mantled by Holocene soil, and surrounded by a lot of till and colluvium. This particular photo shows the most distinct boundary surfac<span id="goog_1233036052"></span><span id="goog_1233036053"></span>e between the clay and surrounding members. It is likely a lens of material formed during episodic activity (see link on Surficial and Bedrock geology). The continuity of the <span id="goog_1040210786"></span><span id="goog_1040210787"></span>glaciomarine member is hard to follow along the north shore, as it is buried under steepland sediments, landslide debris, and thick vegetation. So spotting a slice of the cake is considered good luck for intrepid geological explorers.<br />
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh23dp_4KtHu6iY5bbAdXyBQWGLMTPZmHZNHCRjmz5260w5u4vYnJsgdLycowJagsu86roOBqspYPa88fMsX6n6Q1JAG4Eum3Y7rP9eJttcWsvuZLtYrLlTCpk7kRPXQYWWULxzHl0gNBo/s1600/cryolith.jpg" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh23dp_4KtHu6iY5bbAdXyBQWGLMTPZmHZNHCRjmz5260w5u4vYnJsgdLycowJagsu86roOBqspYPa88fMsX6n6Q1JAG4Eum3Y7rP9eJttcWsvuZLtYrLlTCpk7kRPXQYWWULxzHl0gNBo/s1600/cryolith.jpg" /></a><br />
Additional Info:<br />
<ul><li><a href="http://gsc.nrcan.gc.ca/urbgeo/geomapvan/geomap2_e.php">GSC - Geomap Vancouver</a></li>
<li><a href="http://thesis.library.caltech.edu/5672/1/Roddick_ja_1950.pdf">James Roddick (Caltech) - Some Features of the Geology of the North Vancouver area</a></li>
<li><a href="http://www.gac-cs.ca/publications/VancouverGeologyMap.pdf">GSC - Surficial and Bedrock Geology of the Fraser Lowlands and Coast Mountains near Howe Sound</a></li>
</ul>Malcolm V Lhttp://www.blogger.com/profile/00126268490488546890noreply@blogger.com1tag:blogger.com,1999:blog-2188731877707108811.post-63769748605662523392011-06-25T21:12:00.000-07:002011-06-25T21:12:45.987-07:00Accretionary Wedge #35: No Jive, it's Ogive<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: left; margin-right: 1em; text-align: left;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEihE2zHbg_i6btmIz_9n7Uv5etn8YqW1F25E1YNbbjY5r7CMGBqFpArcSNZZDCImE0gpOEI2a7yspNA9qsovU5anNOTcqzwoyWdOTDZqmtNtrJp43KDodoR_fnawpIFqCWYh9fhYnFY3IQ/s1600/1333382367_0d5c5a960c_o.jpg" imageanchor="1" style="clear: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="400" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEihE2zHbg_i6btmIz_9n7Uv5etn8YqW1F25E1YNbbjY5r7CMGBqFpArcSNZZDCImE0gpOEI2a7yspNA9qsovU5anNOTcqzwoyWdOTDZqmtNtrJp43KDodoR_fnawpIFqCWYh9fhYnFY3IQ/s400/1333382367_0d5c5a960c_o.jpg" width="261" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Gilkey glacier ogives, rimmed by medial moraines<br />
(58° 49.280'N 134° 21.481'W)</td></tr>
</tbody></table>Evelyn over at <a href="http://georneys.blogspot.com/2011/06/accretionary-wedge-35-whats-your.html">Georneys</a> is hosting AW #35, and the bloggers of the geoblogosphere are submitting their favorite geology words. Coming up with a favorite geoscience word was tough. I thought of going for the <a href="http://en.wikipedia.org/wiki/Slaty_cleavage#Types_of_cleavage">comically crude</a>, but none would have been my favorite. So I went from experience and what pops into my head first. On the rare occasion I've ventured across the top of a glacier, and when doing so my companions and I always played a game of 'spot the feature'. You had to get right the specific type of <a href="http://en.wikipedia.org/wiki/Crevasse#Types">crevasse</a> or <a href="http://en.wikipedia.org/wiki/Moraine#Types_of_moraines">moraine</a>, and there were no points for pointing out firn or glacial ice. My greatest success at spotting a feature was straight off the chopper at the Gilkey trench in the <a href="http://en.wikipedia.org/wiki/Juneau_Icefield">Juneau Icefield</a>. The Gilkey glacier had these strange alternating bands of light and dark crescents pointing westwards towards Berner's Bay. <b><span style="font-size: large;">"Ogives!"</span></b><br />
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So what are these patterns on the surface of valley glaciers, and how do they form? <a href="http://en.wikipedia.org/wiki/Ogive_%28glacier%29">Ogives</a> are curved bands across the surface of a glacier, with convexity facing downhill. The bands are characterized by alternating dark and light groupings. The darker bands are devoid of ice-bubbles, are formed from melting & refreezing of ice in the summertime, and contain sediment accumulated at icefalls where open crevasses become a pit of deposition. The lighter bands are filled with snow & air bubbles from the non-summer months when precipitation is greatest, and a fresh snowpack acts as a layer of protection against weathering. Thus ogives are a seasonally created phenomenon. The crescent shape is due to velocity/friction differences between the lateral edges of a glacier where velocity is low & friction is high, and the center of a glacier where velocity is high & friction is low. <br />
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<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgJj4c8qf2XF8zdYt2QLTTmbJelp1wHSF5ONCA30hNv2Sx_3JKvp9Gl69w4CjKAXer22N8iDyQFpQ9Lv7Aj8kB4olAEPdTpIA70zv9N4WdSotlJdUSxnlVaq32MroQZ0aM6gXRub1EqhZE/s1600/glacialflowlines.png" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="102" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgJj4c8qf2XF8zdYt2QLTTmbJelp1wHSF5ONCA30hNv2Sx_3JKvp9Gl69w4CjKAXer22N8iDyQFpQ9Lv7Aj8kB4olAEPdTpIA70zv9N4WdSotlJdUSxnlVaq32MroQZ0aM6gXRub1EqhZE/s320/glacialflowlines.png" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">glacial flow lines relative to surrounding bedrock</td></tr>
</tbody></table>Due to their darker color, the summer bands have greater conductivity to <a href="http://en.wikipedia.org/wiki/Insolation">solar radiation</a>, and thus are topographically lower due to increased melting. My experience traversing the Gilkey glacier was that the trough created is noticeable but pretty minimal, on the order of a 8-10 foot amplitude between a dark bands trough and a light bands crest. Interestingly, the combined width of one light + one dark band corresponds to the distance a glacier traveled in a year, thus it is a proxy element of <a href="http://en.wikipedia.org/wiki/Glacial_motion">glacial motion</a> that can give a decent measurement of an advancing glaciers speed. <br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgpVQIgY2OqViV2xxq3qmmCjB4gV1_e3JzuOFaJcTzSxSwTQ7MJPjUKhbZsP2RmvsI8b-UdEV1t2V738k6r5nMzF1XO-Y6VTRaI1NGWZlz8TtsmCYw3IQz9Z7Mw58M2Al88AzHH8jiEbP4/s1600/Untitled-1.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="242" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgpVQIgY2OqViV2xxq3qmmCjB4gV1_e3JzuOFaJcTzSxSwTQ7MJPjUKhbZsP2RmvsI8b-UdEV1t2V738k6r5nMzF1XO-Y6VTRaI1NGWZlz8TtsmCYw3IQz9Z7Mw58M2Al88AzHH8jiEbP4/s640/Untitled-1.jpg" width="530" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">During summer, the glacier's surface melts and crevasses collect windblown particles, creating the dark band<br />
During winter, the surface is covered with snow, protecting it from weathering and creating the light band</td></tr>
</tbody></table>There you have it. Ogives! A wonderful pattern seen in some of natures freezers. The Vaughn icefall in the Juneau Icefield is as close to an idealized conveyor belt of the banded pattern you can get, but there are others. Soon I plan to visit <a href="http://en.wikipedia.org/wiki/Mt_Rainier">Mt. Rainier</a>, whose alpine glaciers are purported to have some of their own ogives.<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjGS365z9-IHhDT_jNhx8nbbzOsdZC2IiGGR_DWfqbcp0nc6rvA7hd2pa9Pv6pz9ixsCNa864PqM3v0lb5vE52xOg3BR_7XPdm_GXTbTDM_cbcu2hMX6tbw947mf3dzo-MmsD25dK8HUvo/s1600/mer-de-glace-ogives.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="361" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjGS365z9-IHhDT_jNhx8nbbzOsdZC2IiGGR_DWfqbcp0nc6rvA7hd2pa9Pv6pz9ixsCNa864PqM3v0lb5vE52xOg3BR_7XPdm_GXTbTDM_cbcu2hMX6tbw947mf3dzo-MmsD25dK8HUvo/s640/mer-de-glace-ogives.jpg" width="530" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">A valley glacier replete with ogive banding, stemming from near Mont Blanc in the Graian Alps</td></tr>
</tbody></table>(Credit goes to Sue Ferguson for the title of this post, an homage to her excellent guide book "<a href="http://www.amazon.ca/Glaciers-North-America-Sue-Ferguson/dp/1555910750">Glaciers of North America: A field guide</a>")<br />
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Additional Info:<br />
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiHPQTWFuV7zVBCF4sAsZScQRr16Y6E8-ZFtl64Tpl4va9I06yTkdJYYefVDV4e67MwtpRuF-tX_W-c_ynJo34AMcoi7ptlizs0ygZgBiBQtPphGiQqJq93pUBLl_KCfa6lwnS-lzt8MVs/s1600/cryo.jpg" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiHPQTWFuV7zVBCF4sAsZScQRr16Y6E8-ZFtl64Tpl4va9I06yTkdJYYefVDV4e67MwtpRuF-tX_W-c_ynJo34AMcoi7ptlizs0ygZgBiBQtPphGiQqJq93pUBLl_KCfa6lwnS-lzt8MVs/s1600/cryo.jpg" /></a></div><ul><li><a href="http://instaar.metapress.com/content/u306474237p721v3/">Arctic, Antarctic, and Alpine Research - Yamaguchi et al. on the <span style="font-size: small;">Influence of Debris Cover on Ogive-like Surface Morphology of Bilchenok Glacier in Kamchatka</span></a></li>
<li><span style="font-size: small;"><a href="http://pubs.usgs.gov/of/2004/1216/no/no.html">USGS Glossary of Glacial Terminology</a> </span></li>
<li><span style="font-size: small;"><a href="http://www.jstor.org/pss/30058442">Ogives of the East Twin Glacier, Alaska - Their Nature and Origin</a> </span></li>
<li><span style="font-size: small;"><a href="http://glacierchange.wordpress.com/">From a Glaciers Perspective</a> </span><span style="font-size: small;"> </span></li>
</ul>Malcolm V Lhttp://www.blogger.com/profile/00126268490488546890noreply@blogger.com0tag:blogger.com,1999:blog-2188731877707108811.post-16658726874411459722011-06-20T08:54:00.000-07:002011-06-20T08:54:45.203-07:00Kata Tjuta - the forgotten sibling<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhpn2rCVf3XV2ix6WcA-zj2DD_KUtKHs3fkVaYaeUgosnCOCvNJ2UM3SxVkv6Q86CA5I5hKpZ8QS2SKucyis0WH8qCYS_v8sB0t-jm8cb1kgJVxB1JqW-pfAbLRTVyLXFMK263RaH9Gc2Q/s1600/MC_Olgas_pano.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="200" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhpn2rCVf3XV2ix6WcA-zj2DD_KUtKHs3fkVaYaeUgosnCOCvNJ2UM3SxVkv6Q86CA5I5hKpZ8QS2SKucyis0WH8qCYS_v8sB0t-jm8cb1kgJVxB1JqW-pfAbLRTVyLXFMK263RaH9Gc2Q/s640/MC_Olgas_pano.jpg" width="530" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Kata Tjuta, <a href="http://en.wikipedia.org/wiki/Anangu">Anangu</a> for "many heads"</td></tr>
</tbody></table><a href="http://en.wikipedia.org/wiki/Uluru">Uluru</a> is a sandstone gem of Australia's interior landscape. It rises off the plain as a formidable <a href="http://en.wikipedia.org/wiki/Inselberg">inselberg</a> of rusty red solitude. It's what comes to mind about the Australian countryside for many non-Australians, whether as the Anangu name or the anglicized 'Ayers Rock'. Savvy geologists, physiographers, and locals, however, will know about the lesser known gem of conglomerate rock domes not 30 kilometers to the west of Uluru. The Olgas, known as <a href="http://en.wikipedia.org/wiki/Olgas"><i>Kata Tjuta</i></a> in the Anangu language, are a collection of 36 conglomerate rock domes rising off the plain to various heights. The highest is Mount Olga, with a prominence of 546m.<br />
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<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhZUoEo6Xg5e7KN9NPJ87VHiP0km0W_0b6Pih7QtH4srljpDIqdOqZ6vaWfYjV2ikkmhklcJKEtICpWedeC3mHJSOfMzuhWRBp_b3BRhBVyJX3nhT3Klf9qxX1C4A3SSvgWhsZIJdq6fxo/s1600/Schema_Kata_Tjuta_Uluru.png" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="113" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhZUoEo6Xg5e7KN9NPJ87VHiP0km0W_0b6Pih7QtH4srljpDIqdOqZ6vaWfYjV2ikkmhklcJKEtICpWedeC3mHJSOfMzuhWRBp_b3BRhBVyJX3nhT3Klf9qxX1C4A3SSvgWhsZIJdq6fxo/s200/Schema_Kata_Tjuta_Uluru.png" width="200" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Basic stratigraphic cross-section of<br />
Uluru and Kata Tjuta</td></tr>
</tbody></table>Kata Tjuta is part of the same stratigraphic formation as Uluru (see diagram at right), a unit of arkosic sandstone derived from Cambrian alluvial fan deposits of sediment that were buried and lithified over deep time. The difference in shape & topography between the two is due to the structurally weaker conglomerate of the Olgas (the <a href="http://dbforms.ga.gov.au/pls/www/geodx.strat_units.sch_full?wher=stratno=12609">Mount Currie Conglomerate</a>) being exploited by folding, faulting, and subsequent hydrologic weathering & erosion. The conglomerate matrix is comprised of granodiorite, basalt, gneiss, and fine sand as the cementing material. Essentially, Uluru is the tougher end of the layer, though it does not lack features created from weathering such as pits and <a href="http://en.wikipedia.org/wiki/Tafoni">tafoni</a>-based honeycomb surfaces (indicative of <a href="http://en.wikipedia.org/wiki/Mediterranean_climate">Mediterranean</a> paleoclimates). Even though the conglomerate lithology of Kata Tjuta lacks the feldspar mineral content that Uluru has, fractured blocks were exploited, making the initial mass structurally weaker, even though it is mineralogically stronger. Both ends started out as a large singular massive block, but Cenozoic Australian climates have taken a greater toll on the Olgas for the reasons stated.<br />
<br />
Back in the <a href="http://en.wikipedia.org/wiki/Neoproterozoic">Neoproterozoic</a>, the <a href="http://www.britannica.com/EBchecked/topic/453890/Petermann-Ranges">Petermann mountain range</a> was more formidable than it is today, due in major part to the <a href="http://en.wikipedia.org/wiki/Petermann_Orogeny">Petermann orogeny</a>. However, the Neoproterozoic/early Paleozoic climate was more temperate, so its peaks were being denuded by precipitation at a greater rate than the more subdued Holocene landscape is by current <a href="http://en.wikipedia.org/wiki/Aeolian_processes">aeolian forces</a>. <a href="http://en.wikipedia.org/wiki/Alluvial_fan">Alluvial fans</a> were created along the flanks of the Petermann foothills, each differing slightly in lithology, but not in origin. These fans formed a piedmont range that was a major part of Petermann <a href="http://en.wikipedia.org/wiki/Foreland_basin">foreland basins</a>, such as the <a href="http://en.wikipedia.org/wiki/Amadeus_Basin">Amadeus</a>, <a href="http://en.wikipedia.org/wiki/Georgina_Basin">Georgina</a>, <a href="http://en.wikipedia.org/wiki/Ngalia_Basin">Ngalia</a>, and <a href="http://en.wikipedia.org/wiki/Officer_Basin">Officer</a> basins of then central Australia. The fan material developed sequentially into <a href="http://en.wikipedia.org/wiki/Flysch">flysch</a> once a eustatic change in sea level occurred in the late Cambrian, covering the region in a shallow sea. Continuing weight of added sediment + the weight of the increasingly deepening sea was enough pressure to lithify the alluvial fans/flysch into <a href="http://en.wikipedia.org/wiki/Arkose">arkosic sandstone</a> (Uluru) & conglomerate (Kata Tjuta), each portion representing a different fan thus a slightly different lithology, all connected together during the melding of adjacent sedimentary units. If we could remove the overburden of sand & schist members, we likely could find the area where the conglomerate and sandstone grade into each other.<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhJMP0uwBhT-_anY5eQlAQO12cCpMn6N3k5C14XPATfG332R6O878WmIE2sGNXu3RHKKTUfN4TxMdykn4v1jHskdXZb8A52SZEi2u8Wz_iLovedVTKjQXzci5zbzayKlrUsCtqPeWNxfz4/s1600/Untitled.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="187" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhJMP0uwBhT-_anY5eQlAQO12cCpMn6N3k5C14XPATfG332R6O878WmIE2sGNXu3RHKKTUfN4TxMdykn4v1jHskdXZb8A52SZEi2u8Wz_iLovedVTKjQXzci5zbzayKlrUsCtqPeWNxfz4/s640/Untitled.png" width="530" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Google Earth snapshot of Central Australian plain, with Kata Tjuta @ left and Uluru @ right (VE = 3x)<br />
Coordinates for centerpoint = 25° 18.710'S 130° 53.730'E</td></tr>
</tbody></table>Australia was quite geomorphically active during the Paleozoic; a contrast to the quiet old continent of today where relief and rates of denudation are comparatively low, and atmospheric hazards dominate. After the <a href="http://en.wikipedia.org/wiki/Transgression_%28geology%29">transgression</a> of the early Paleozoic, the sea receded and orogenic activity took over in the Devonian, thrusting and folding and faulting Central Australia, to the point that the Mount Currie Conglomerate formation folded with surrounding units into a distinct <a href="http://en.wikipedia.org/wiki/Syncline">syncline</a>. The Late Paleozoic – Mesozoic – Tertiary periods began a slow march of weathering & erosion of overburden, until the exposure of the ends of the Mount Currie Conglomerate finally revealed a more resistant rock. Exposure to the atmosphere is estimated to have occurred during the Jurassic. A basin between Uluru and Kata Tjuta collected aeolian sands and dunes throughout the Quaternary, thus planing the region through depositional mechanisms. All that stood out in the plain were the tips of rocks derived from a resistant lithology. The rock domes of Kata Tjuta specifically dip 10-20º with a SW-NE strike.<br />
<br />
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh_A2W4upygph8wfUpqYgpq_S5SLvWFAtRZuyrGBuM0kDuskdMe_-da7m7-vPnVolD1VnEbNzsr5BNZ7UZ5_DASyZs1dKXgRjMNUlKsjkYCJj_qEg7VDRH-y_3WwtAr8-zQCH5NcHGJPqI/s1600/olga.png" imageanchor="1" style="clear: left; float: left; margin-bottom: 1em; margin-right: 1em;"><img border="0" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh_A2W4upygph8wfUpqYgpq_S5SLvWFAtRZuyrGBuM0kDuskdMe_-da7m7-vPnVolD1VnEbNzsr5BNZ7UZ5_DASyZs1dKXgRjMNUlKsjkYCJj_qEg7VDRH-y_3WwtAr8-zQCH5NcHGJPqI/s320/olga.png" width="265" /></a>The finer features of the Olgas have been primarily shaped by precipitation during more temperate <a href="http://en.wikipedia.org/wiki/Paleoclimate">paleoclimatic</a> conditions. <a href="http://en.wikipedia.org/wiki/Freeze_thaw">Freeze-thaw processes</a> acted on joints in the rock, fracturing the surface. Rivulets of creeks and small waterfalls promoted the formation of potholes and gorges. Since granite is a primary ingredient in the Kata Tjuta Mount Currie conglomerate, <a href="http://en.wikipedia.org/wiki/Spheroidal_weathering">spheroidal weathering</a> was able to smooth and accentuate a rounded dome shape to the remaining 36 mini-<a href="http://en.wikipedia.org/wiki/Bornhardt">bornhardts</a> by working on the angles & corners. Of course, iron content exposed to the atmosphere colored the veneer of Kata Tjuta to that typical iron oxide rusty-red. Some visible structures noticeable when perusing the rocks include limited tafoni structures among the rock domes. <a href="http://en.wikipedia.org/wiki/Slickensides">Slickensides</a> are also apparent, indicating displacement of large sheets of the conglomerate during times of acute mass wasting.<br />
<br />
As an aside, I stumbled upon an interesting take on the formation of Kata Tjuta when google-searching: <a href="http://biblicalgeology.net/Geological-Histories/Kata-Tjuta.html">Tas Walker's Noachian interpretation of Kata Tjuta</a>. It is a prime example of working backwards with the <a href="http://en.wikipedia.org/wiki/Scientific_method">scientific method</a>, where a proposed theory is the starting point, and evidence to support it is <a href="http://en.wikipedia.org/wiki/Anecdotal_evidence">anecdotally</a> surmised to fit that theory. Remember, if a <a href="http://en.wikipedia.org/wiki/Null_hypothesis">null hypothesis</a> cannot be rejected, and credibility cannot be established through peer review, it is not science, and certainly not geomorphology science. Current [accredited] geomorphology research reveals noticeable increase in relief amplitude of both Uluru and Kata Tjuta inselbergs throughout the Cenozoic, which is atypical of the ideal <a href="http://en.wikipedia.org/wiki/Cycle_of_erosion">cycle of erosion</a> (see additional links). Interesting mechanisms must be at play, and a deeper look into the asthenosphere, lithospheric flexure, and the mass dynamics between the overburden and the Mount Currie Conglomerate are called for.<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEikJtoUIHHFS65Oxtklm0qHq9n3SM_0t3r92SwWHqUZyUkWhsS9zd6fDc3rl7FEM4dIe_3t5prWUHqfXw-ToddMOCYMrvlNRjD3un2ylJSFFGXYuqo8_694P7KsIof5ONvXQoP-VeZ2mLU/s1600/3213760241_a0b88e8568_o.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="283" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEikJtoUIHHFS65Oxtklm0qHq9n3SM_0t3r92SwWHqUZyUkWhsS9zd6fDc3rl7FEM4dIe_3t5prWUHqfXw-ToddMOCYMrvlNRjD3un2ylJSFFGXYuqo8_694P7KsIof5ONvXQoP-VeZ2mLU/s640/3213760241_a0b88e8568_o.jpg" width="540" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Thanks to my brother for the above photo of the Olgas, circa 2007</td></tr>
</tbody></table><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjloSOn-6xuJ6D2cillA1G6D9a9FY0iTHqY9fO48AikcLsSDoymkbddzXR2o-QS6qRII7bAp7g31XJWaheeH_nIC4LU4Zyqs4nucoNMoizS-slCvizM617gY_8x5q555PHmC9MkV_D-Ymk/s1600/litho.jpg" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjloSOn-6xuJ6D2cillA1G6D9a9FY0iTHqY9fO48AikcLsSDoymkbddzXR2o-QS6qRII7bAp7g31XJWaheeH_nIC4LU4Zyqs4nucoNMoizS-slCvizM617gY_8x5q555PHmC9MkV_D-Ymk/s1600/litho.jpg" /></a>Additional Info:<br />
<ul><li><a href="http://www.youtube.com/watch?v=3NgNtcrO8x4">Uluru Kata Tjuta, Northern Territory</a></li>
<li><a href="http://en.wikipedia.org/wiki/Uluru-Kata_Tjuta_National_Park">Uluru - Kata Tjuta National Park in the Northern Territory </a></li>
<li><a href="http://books.google.com/books?id=-TI55urJYyEC&pg=PA321&lpg=PA321&dq=Wells+Ayers+rock+1970&source=bl&ots=7SF3M3rmUg&sig=7yu0i2lncHcPSF-PRLsGUR5-qMA&hl=en&ei=PZSSTfHYKY2Q0QHtkd3MBw&sa=X&oi=book_result&ct=result&resnum=1&ved=0CBQQ6AEwAA#v=onepage&q=Wells%20Ayers%20rock%201970&f=true">Uluru and Kata Tjuta: Inselbergs of Central Australia</a></li>
<li><a href="http://www.sciencedirect.com.ezproxy.kwantlen.ca:2080/science/article/pii/0012825276900040">R.W.R. Rutland - Orogenic Evolution of Australia </a></li>
<li><a href="http://en.wikipedia.org/wiki/File:MC_Olgas_pano.jpg">Wikipedia - The Olgas panorama</a></li>
</ul>Malcolm V Lhttp://www.blogger.com/profile/00126268490488546890noreply@blogger.com0tag:blogger.com,1999:blog-2188731877707108811.post-87460417009947220852011-06-11T09:49:00.000-07:002011-06-11T09:49:32.797-07:00A new toy! Can I play?I like volunteering. You meet compassionate people with similar interests & concerns in an informative setting. However, I live in the realities of a capitalist western country, so the [very] limited free time I have outside of university studies restricts my volunteerism, as it logically is the first thing to get cut during crunch time and the search for funds. Summertime is a bit different: classes are few or nonexistent, daylight is plentiful, and my general mood is happier & more energetic. Consequently, I tend to volunteer with local organizations that have environmental directives, and over the years I've found a few that have programs which are laid out in a simplistic fashion, and thus easy to volunteer portions of my free time for. <a href="http://www.tol.ca/CurrentNewsInitiatives/Initiatives/WaterWiseCommunity.aspx">One in particular</a> I'm on my 4th year with involves canvassing residents of Langley on how to protect their dwindling groundwater supply through conservation and community action (~50% of the townships water supply is provided by <a href="http://img.photobucket.com/albums/v253/RavenessM/Geo/Langleyaquifers.jpg">unconfined or shallow-confined aquifers</a>).<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi8v-8oaJ5rOj9L6wycvEyG77weJpb_ZLv0nyZQyl7fPyXhJr3WATu8IwV1PQ5K4Ah_oRjQqhpq30BciH0LoeJ4RipnikQ1BnRjpRVWdXIzbp_dNhK8DOL37BtH9FeE8gJfTncaENPPGG0/s1600/Picture+002.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="341" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi8v-8oaJ5rOj9L6wycvEyG77weJpb_ZLv0nyZQyl7fPyXhJr3WATu8IwV1PQ5K4Ah_oRjQqhpq30BciH0LoeJ4RipnikQ1BnRjpRVWdXIzbp_dNhK8DOL37BtH9FeE8gJfTncaENPPGG0/s640/Picture+002.jpg" width="530" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">A sample of vesicular basalt as a control in an experiment. The sample was obtained from <a href="http://en.wikipedia.org/wiki/Mount_Rainier">Mt. Rainier</a></td></tr>
</tbody></table>In more recent years, with my growing interest in academic research, I've started asking university professors if they or their grad students need any field/lab assistance with their research. Any that have ongoing work always say yes, and when I come in with enthusiasm and interest in reading & discussing their work, they shoot back with an even greater level of enthusiasm. Probably the best aspect of volunteering in labs or the field is not the possibility of paid work, nor the time to pick the brains of current researchers, nor getting my foot in the door. Those are all excellent aspects, but the best has to be the exposure to the precision technology that I get to [cautiously] fiddle with and test out, and see its application towards specific facets of quantified research.<br />
<br />
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgqkOgKxtIWwM_hO3oXcBNU1EKhpD8tK8TR9TiJBx3TTl8l2Zsr8qprhdot-5HI4nuTcSHp8vWsMObdCPO2XWdSo1kW5r68x0HRfqqpb-oqaziOk38_bUMvZP8DQ-U0XFNyvoIhyphenhyphenxUXWL0/s1600/He_pycno.jpg" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgqkOgKxtIWwM_hO3oXcBNU1EKhpD8tK8TR9TiJBx3TTl8l2Zsr8qprhdot-5HI4nuTcSHp8vWsMObdCPO2XWdSo1kW5r68x0HRfqqpb-oqaziOk38_bUMvZP8DQ-U0XFNyvoIhyphenhyphenxUXWL0/s320/He_pycno.jpg" width="240" /></a>One recent new addition to the university had the petrologist professor quite giddy, and him and I got to play around with the new device for awhile, figuring out all its quirks and functions, and running some initial control tests to ensure proper functionality. The device was something I'd never heard of before, but the explanation of its logic and level of precision made perfect sense. I speak of a <a href="http://en.wikipedia.org/wiki/Gas_pycnometer">Helium-based pycnometer</a> (pictured right).<br />
<br />
<div style="font-weight: normal; margin-bottom: 0.5cm;">It is hard to get an accurate measurement of density for vesicular rocks, such as vesicular basalt, pumice, scoria, etc... due to the irregular arrangement of void space in their matrix where gasses exsolved. <a href="http://en.wikipedia.org/wiki/Helium">Helium</a> is a relatively inert gas, so functions better than a <a href="http://en.wikipedia.org/wiki/Air">nitrogen/oxygen/argon mixture</a> which could be adsorbed by silicic material. Helium is better at diffusing within rock samples of high surface area with the tiniest, micrometer-level pore spaces, ie. vesicular rocks. Thus the displacement of Helium between containers (one with the rocks and one without), and application of the <a href="http://en.wikipedia.org/wiki/Ideal_gas_law">ideal gas law</a>, and we get the volume of the rock sample with deadly accuracy. We tested out the device using some vesicular basalt (pictured above) gathered from pyroclastic flows ejected from <a href="http://en.wikipedia.org/wiki/Cascade_Arc">Cascade Arc volcanoes</a>. Looking at the basalt petrographically was important as well, so I made <a href="http://en.wikipedia.org/wiki/Thin_section">thin sections</a> for viewing under the microscope and we viewed the <a href="http://en.wikipedia.org/wiki/Optical_mineralogy">optical mineralogy</a> of the basalt.<br />
<br />
<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: left; text-align: left;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjHT5ET0Tt6B9QTJQ9hvMlN0yEK2Xt0zw-qJn2sJG_6VywFlfJB7lZPJdJpImrLB70sUM9XpfnAPtCT_X2lKw5kppVdQRVv09FmIj7Eaq5dlt7FCt5twp-DxBjGV6ob8SeW5bFACo1Ifds/s1600/mount-edziza-2027.jpg" imageanchor="1" style="clear: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="208" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjHT5ET0Tt6B9QTJQ9hvMlN0yEK2Xt0zw-qJn2sJG_6VywFlfJB7lZPJdJpImrLB70sUM9XpfnAPtCT_X2lKw5kppVdQRVv09FmIj7Eaq5dlt7FCt5twp-DxBjGV6ob8SeW5bFACo1Ifds/s320/mount-edziza-2027.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Mt Edziza stratovolcano, which has erupted felsic <br />
magmas such as rhyodacite or <a href="http://en.wikipedia.org/wiki/Trachyte">trachyte</a>/<a href="http://en.wikipedia.org/wiki/Comendite">comendite</a>. <br />
Image courtesy <a href="http://www.thecanadianencyclopedia.com/index.cfm?PgNm=HomePage&Params=A1">Canadian Encyclopedia</a></td></tr>
</tbody></table>The pycnometer is supposed to help the professor's research of the geochemistry of the <a href="http://en.wikipedia.org/wiki/Mount_Edziza_volcanic_complex">Edziza volcanic complex</a> within the <a href="http://en.wikipedia.org/wiki/NCVP">NCVP</a>. I hope to assist in as much of it until the concluding phases and journal publication, mainly because it allows further access and experience with new physical geography/geology toys. I've also recently got some fresh experience with a 15m long sediment transport flume, but that's another research tale I hope to tell after more time with the flume.<br />
<br />
For other undergrads I strongly recommend volunteering your time & energy to your university profs and grad students. Trust me, they are likely to welcome your assistance, and you'll benefit from the experience and the contacts, especially if post-graduate studies is on your radar. It gets your foot in the door, and is thus invaluable.<br />
<br />
<div style="margin-bottom: 0cm;">Additional Info: </div><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjloSOn-6xuJ6D2cillA1G6D9a9FY0iTHqY9fO48AikcLsSDoymkbddzXR2o-QS6qRII7bAp7g31XJWaheeH_nIC4LU4Zyqs4nucoNMoizS-slCvizM617gY_8x5q555PHmC9MkV_D-Ymk/s1600/litho.jpg" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjloSOn-6xuJ6D2cillA1G6D9a9FY0iTHqY9fO48AikcLsSDoymkbddzXR2o-QS6qRII7bAp7g31XJWaheeH_nIC4LU4Zyqs4nucoNMoizS-slCvizM617gY_8x5q555PHmC9MkV_D-Ymk/s1600/litho.jpg" /></a></div><ul><li><a href="http://www.sciencedirect.com.ezproxy.kwantlen.ca:2080/science/article/pii/0377027384900179">J.G. Souther and C.J. Hickson - Crystal fractionation of the basalt comendite series of the mount Edziza volcanic complex, British Columbia: Major and trace elements</a></li>
<li><a href="http://heliumpycnometer.com/">Helium Pycnometer</a></li>
<li><a href="http://jersey.uoregon.edu/vlab/Piston/index.html">Ideal Gas Law virtual lab</a></li>
<li><a href="http://www.pitt.edu/%7Ecejones/GeoImages/2IgneousRocks/IgneousTextures/7VesicularAmygdaloidal.html">University of Pittsburgh - Vesicular and Amygdaloidal Textures</a></li>
</ul><ul></ul></div>Malcolm V Lhttp://www.blogger.com/profile/00126268490488546890noreply@blogger.com0tag:blogger.com,1999:blog-2188731877707108811.post-27953830505505665432011-06-06T09:30:00.000-07:002011-06-06T09:30:26.404-07:00Geology at a Birthday Party<div class="separator" style="clear: both; text-align: center;"></div><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhgb1s3fP8lvdmNBv6Xdjx5uj30xw5Fe1Qo1C9QhP5ui64Z80YRBLDWcyTw_9F-tqfWVcDQ1KCLMfVtlmKLJ1LoOwF3Ax8aQt6fTTBh6XZHDbb9S43oPxEMYCdMJMcOGfA5enRy6m-786Y/s1600/Picture.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="412" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhgb1s3fP8lvdmNBv6Xdjx5uj30xw5Fe1Qo1C9QhP5ui64Z80YRBLDWcyTw_9F-tqfWVcDQ1KCLMfVtlmKLJ1LoOwF3Ax8aQt6fTTBh6XZHDbb9S43oPxEMYCdMJMcOGfA5enRy6m-786Y/s640/Picture.jpg" width="550" /></a></div>My niece recently had her 10th birthday, and I felt it fitting to add to her burgeoning rock & mineral collection with some <a href="http://en.wikipedia.org/wiki/Flint">flint</a>, <a href="http://en.wikipedia.org/wiki/Chert">chert</a>, and <a href="http://en.wikipedia.org/wiki/Serpentinite">serpentine</a>. I mentioned the properties of serpentine to her, and its connection to <a href="http://en.wikipedia.org/wiki/Asbestos">asbestos</a>, which is a carcinogen. She must have forgotten the part where I mentioned there is no chance of inhaling carcinogenic asbestos from the fist-sized rock I gave her unless she grinded it into a fine mist, nor does it have the mass of <a href="http://en.wikipedia.org/wiki/Chrysotile">chrysotile</a> needed to make her lungs even notice. But lo and behold a few hours later she had placed a paper on top of her rock box ..."Warning - Cancer rock inside".<br />
<br />
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEioVO0Dcc6xU1hGK85v28k1x9ZuLyzlEhyCCHH0xhE3UojRSSa_7s2psrlgmuYPOd5E53hPFvw7szOnn5cFvBufb4dD7H2297Z159zbfUnBMvxgnRuMmrCxEvVIAWZAkK9x9YuLrkRpQLc/s1600/mohs_hardness_scale.jpg" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" height="156" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEioVO0Dcc6xU1hGK85v28k1x9ZuLyzlEhyCCHH0xhE3UojRSSa_7s2psrlgmuYPOd5E53hPFvw7szOnn5cFvBufb4dD7H2297Z159zbfUnBMvxgnRuMmrCxEvVIAWZAkK9x9YuLrkRpQLc/s320/mohs_hardness_scale.jpg" width="320" /></a></div>An opportunity to educate her on the properties of minerals, and she took to it. Kids get right away that rocks are essentially a collection of minerals in different ratios. I'm amazed at how easy it is for kids to quickly grasp many things geological; Sometimes I wish I had such a malleable mind when I'm engulfed in my university studies. Specific gravity/density is a hard one to explain, but streak powder, cleavage, fracture, hardness, were all easy to demonstrate given that visual demonstration of them is straightforward. If you try this, I would recommend not using the mirror example for <a href="http://en.wikipedia.org/wiki/Mohs_scale_of_mineral_hardness">hardness</a>, as some kids might run off to try it on bathroom mirrors. <br />
<br />
Later on after her party, we sat down to watch some old Simpsons episodes on TV, and <a href="http://en.wikipedia.org/wiki/Treehouse_of_Horror_V">Treehouse of Horror V</a> was what was showing. Homer invented a time machine by modifying a toaster, and it catapulted him back to what appeared to be a blend of the Paleozoic and Mesozoic eras, and even some Neogene (a <a href="http://en.wikipedia.org/wiki/Megatherium">Megatherium</a> alongside a T-Rex??). His father gave him sage advice about not touching anything in the past, as doing so could alter the future in ways he couldn't possibly imagine. Homer was chased by a <a href="http://en.wikipedia.org/wiki/T_rex">T-Rex</a>, eventually escaping. Unfortunately, upon sitting down for a rest, he squashed what is considered the first land-walking animal. I speak of the <a href="http://en.wikipedia.org/wiki/Eusthenopteron">Eusthenopteron</a>:<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEglHYigqjKBuLWtzBcip7Bap1WoVGGzPLT_de7oi-YfWCY1Wr5L5mck5FThUr8olaF8drMnlGt4CrCKGJtn5-jGfvMvYVwMuBUPkDq7ffqTQqLUyODISvxLP1QbYZbtIVPzbvECnZJjtTI/s1600/simpsonseusth.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="152" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEglHYigqjKBuLWtzBcip7Bap1WoVGGzPLT_de7oi-YfWCY1Wr5L5mck5FThUr8olaF8drMnlGt4CrCKGJtn5-jGfvMvYVwMuBUPkDq7ffqTQqLUyODISvxLP1QbYZbtIVPzbvECnZJjtTI/s640/simpsonseusth.png" width="520" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">courtesy 20th Century Fox</td></tr>
</tbody></table>Homer killed the terrestrial evolutionary process! For some reason, that lead to the human race being 50-feet tall giants. Wouldn't it lead to us remaining aquatic animals?? Why am I trying to find evolutionary logic from a late-night cartoon? Meh, I was just pleased to see these archaic lifeforms I'm familiar with used for satire.Malcolm V Lhttp://www.blogger.com/profile/00126268490488546890noreply@blogger.com2tag:blogger.com,1999:blog-2188731877707108811.post-81997951142037209942011-05-31T09:09:00.000-07:002011-05-31T09:09:01.919-07:00Papers I'm reading: Trends in the timing and magnitude of floods in Canada<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi7A21QvOCFfUbQZu0jwqhyPahrObDH7kliy-Is6nfq0jm6FYkXzZ9yzXF2Qicrxs5Xi8fQAKTVaId1Po_JmOM0_xXEbCnJz-e9oFuSSDJ7T4rJOzyrbkKwR2IuPaFvIAmMdPCjCZeCFVA/s1600/GIShydrowestCan.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="405" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi7A21QvOCFfUbQZu0jwqhyPahrObDH7kliy-Is6nfq0jm6FYkXzZ9yzXF2Qicrxs5Xi8fQAKTVaId1Po_JmOM0_xXEbCnJz-e9oFuSSDJ7T4rJOzyrbkKwR2IuPaFvIAmMdPCjCZeCFVA/s640/GIShydrowestCan.png" width="550" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">GIS map of the <a href="http://atlas.nrcan.gc.ca/site/english/index.html">Atlas of Canada</a>, showing numerous hydrometric measurement stations in the western half of the country</td></tr>
</tbody></table><div class="separator" style="clear: both; text-align: center;"></div>In case anyone hasn't noticed, Canada is huge. The country's vast area and varied topography lends itself to a multitude of different hydrological regimes, influenced atmospherically on a meso-macro scale by Polar & Tropical air masses. The warm vs cold air mass war has its battleground across the latitudes of Canada, from 42° - 66.6°N, with the only region that can be called "calm" being the ice-capped tundra islands north of the Arctic Circle. Very few places in Canada do not receive decent snowfall, so spring freshet runoff from snowpack melt is typical, and measuring it is every Canadian fluvial hydrologists nitty-gritty. <br />
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiGzLqkwYuUnDGPdpVt7tW7oVvm3AyIkpsF7gQ6VO0-h94I55-aSM9a5Y0osOFsy3lWR_bywzcFBnHPYsXEtERY3qiqdAxBd45ljg21HAqqTe4siU8h6bwuAc9P9wOQUTj5EEF-O2_YUOo/s1600/BCairport.jpg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiGzLqkwYuUnDGPdpVt7tW7oVvm3AyIkpsF7gQ6VO0-h94I55-aSM9a5Y0osOFsy3lWR_bywzcFBnHPYsXEtERY3qiqdAxBd45ljg21HAqqTe4siU8h6bwuAc9P9wOQUTj5EEF-O2_YUOo/s1600/BCairport.jpg" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Bella Coola airport during Sept. 2010 flood<br />
A prime example of a rainfall-induced flood</td></tr>
</tbody></table><br />
Climate change towards a warming trend must have an impact on the various hydrological regimes and how the <a href="http://en.wikipedia.org/wiki/Hydrologic_cycle">hydrologic cycle</a> has been altered due to that impact. As I've said, there are a multitude of different hydrological regimes, so there are likely a multitude of different trends. This line of thought brought me to an academic paper in the <a href="http://www.sciencedirect.com/science/journal/00221694">Journal of Hydrology</a> that reviews trends in timing & magnitude of floods in Canada due to hydrologic shifts, and does so by looking at the established <a href="http://atlas.nrcan.gc.ca/site/english/maps/environment/land/arm_physio_reg">physiographic regions of Canada</a>. Juraj Cunderlik and Taha Ouarda from the <a href="http://www.nserc-crsng.gc.ca/index_eng.asp">Natural Sciences and Engineering Research Council of Canada</a> Chair on Statistical Hydrology analyzed flood data gathered from several dozen strategically placed monitoring stations throughout the hydrometric network of Canada.<br />
<blockquote><span style="font-size: x-small;">This study investigates trends in the timing and magnitude of seasonal maximum flood events across Canada. A new methodology for analyzing trends in the timing of flood events is developed that takes into account the directional character and multi-modality of flood occurrences. The methodology transforms the directional series of flood occurrences into new series by defining a new location of the origin. A test of flood seasonality (multi-modality) is then applied to identify dominant flood seasons. Floods from the dominant seasons are analyzed separately by a seasonal trend analysis. The Mann–Kendall test in conjunction with the method of pre-whitening is used in the trend analysis. Over 160 streamflow records from one common observation period are analyzed in watersheds with relatively pristine and stable land-use conditions. The results show weak signals of climate variability and/or change present in the timing of floods in Canada during the last three decades. Most of the significant trends in the timing of spring snowmelt floods are negative trends (earlier flood occurrence) found in the southern part of Canada. There are no significant trends identified in the timing of fall rainfall floods. However, the significance of the fall, rainfall-dominated flood season has been increasing in several analyzed watersheds. This may indicate increasing intensity of rainfall events during the recent years. Trends in the magnitude of floods are more pronounced than the trends in the timing of floods. Almost one fifth of all the analyzed stations show significant trends in the magnitude of snowmelt floods. Most of the significant trends are negative trends, suggesting decreasing magnitudes of snowmelt floods in Canada over the last three decades. Significant negative trends are found particularly in southern Ontario, northern Saskatchewan, Alberta and British Columbia. There are no significant trends in the magnitude of rainfall floods found in the analyzed streamflow records. The results support the outcomes of previous streamflow trend studies conducted in Canada. </span></blockquote><b>What did they find? (delving into the abstract's details)</b><br />
<br />
The study first defines some ground rules:<br />
<ul><li>Minimum of 20 years of observational data</li>
<li>Statistically significant flood regimes usually have bimodal seasons (spring freshet season + fall rainfall season).<span style="font-family: Times New Roman,serif;"> </span>There were no stations identified with three or more significant flood seasons. </li>
<li>Watersheds used in the statistical study are characterized by relatively pristine and stable land-use conditions, with less than 5% of the watershed area being modified by human development</li>
<li>It is not feasible to get thorough coverage of streamflow data across Canada due to the country's sheer breadth, and inaccessibility of certain regions</li>
<li>The pulse day = the day for which the cumulative departure of the streamflow from the average streamflow for the year is most negative. Most acutely observed during the spring freshet season within high relief terrain</li>
</ul><ul></ul><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhd8EWvl11tCt0HeFAZ3PUcGoJ9sTKsKrdPUaBKNBPzoe2kTLwNZeY6V6uGQEG8Of3WZ0EwJFX7Ol16UZ45WAN2453vU7xZKoXm21VwvO9j6gOVQrxCMyAEyRWcBwgH4RNa6OUlvCkPexU/s1600/Modalrain.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="362" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhd8EWvl11tCt0HeFAZ3PUcGoJ9sTKsKrdPUaBKNBPzoe2kTLwNZeY6V6uGQEG8Of3WZ0EwJFX7Ol16UZ45WAN2453vU7xZKoXm21VwvO9j6gOVQrxCMyAEyRWcBwgH4RNa6OUlvCkPexU/s640/Modalrain.png" width="500" /></a></div><div style="font-weight: normal; margin-bottom: 0.5cm;">I'm not going to detail their establishment of a statistical methodology to gauge multi-modal flooding seasons, as I'm more interested in the findings about floods in the country (statistical know-how is something I'm lacking, soon to be remedied). In terms of timing trends, readings in southern Canada over the last generation are showing a trend towards earlier spring melt floods. This trend is particularly acute in southern Ontario, Alberta, and BC. Changes in freshwater ice break/freeze up spring dates are strongly linked to large-scale atmospheric and oceanic oscillations, with positive feedback mechanisms as the driving force. Only 16 stations, which is 10% of those included in the study, had a statistically significant trend in the timing of spring freshet floods during the last generation. Of those 16, 14 had a negative trend pointing to earlier occurrence. Only 2 stations had a positive trend pointing to later occurrence of spring floods, and those were in the tundra of <a href="http://en.wikipedia.org/wiki/Nunavut">Nunavut</a>.<br />
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgyxSmep5VzWuNZAdMPYwH_vDRq8zwO1zURcc8Z6r1AoGgaJWvyrl9bM2WOEte-8-R9CsEGdn7y_uNmEfS0bgR62YWHq9FUFlcJXiNjLqlX6nPkc3p2AaVocxZAZviofMI8Ox3uAo0XTvg/s1600/Timingtrend.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="390" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgyxSmep5VzWuNZAdMPYwH_vDRq8zwO1zURcc8Z6r1AoGgaJWvyrl9bM2WOEte-8-R9CsEGdn7y_uNmEfS0bgR62YWHq9FUFlcJXiNjLqlX6nPkc3p2AaVocxZAZviofMI8Ox3uAo0XTvg/s640/Timingtrend.png" width="500" /></a></div></div><div style="font-weight: normal; margin-bottom: 0.5cm;"><div style="font-weight: normal; margin-bottom: 0.5cm;">The real crux of the study is the findings about the change in flood magnitudes, as the values associated with volume/discharge are more striking than the shifts in the timing of said discharge. There is only a weak trend in having earlier melt runoffs, but a more significant trend in having a lower magnitude of those melt runoffs. The trend shows decreasing streamflow in heavily glaciated areas (ie. alpine glaciers of Rockies, valley glaciers of sub-Arctic & western Cordillera) during the typical spring runoff season for those areas of April - July. On average, the mean annual spring maximum flows have decreased by approximately 1% per year over the analyzed period of 1974 - 2003. My home province of BC had some intriguing findings: there was some significant increasing trends in spring maximum flows (increased snowmelt-induced flows) and significant decreasing trends at the beginning of summer (reduced snowmelt-induced flows); this is essentially showing that the snowpack is melting at a greater pace earlier in the season, leaving the summer months less supplied with meltwater from the snowpack. This is not a good trend as that scenario exacerbates drought conditions typical of BC in the summer, when a persistent <a href="http://en.wikipedia.org/wiki/North_Pacific_High">Pacific High</a> settles over the region. Indeed the paper finds that accompanying climate data (air temps) are shifting at a quicker-than-anticipated pace from the coldest to the warmest season, causing greater flow spikes in response.</div><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjHK2WyDvakP1pH18Fx6Mg_OC7oGOGYQDDM7yR1chI6HexKZAfnRPNx_2cl93DGd-Vp4ak4gaut7cB2Us7SSS77uUIArLC3RddEck34VlcVdx3ROLR9Okn4ZQhrJYYcMnI2yZkg6IGP5_s/s1600/Magtrend.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="389" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjHK2WyDvakP1pH18Fx6Mg_OC7oGOGYQDDM7yR1chI6HexKZAfnRPNx_2cl93DGd-Vp4ak4gaut7cB2Us7SSS77uUIArLC3RddEck34VlcVdx3ROLR9Okn4ZQhrJYYcMnI2yZkg6IGP5_s/s640/Magtrend.png" width="500" /></a></div><div style="font-weight: normal; margin-bottom: 0.5cm;"></div></div><b>You mentioned "bimodal". What about the fall rainfall season trends?</b><br />
Almost a non-issue amongst the observed data. The authors note only a potential for increasing rainfall during the fall season, as certain regions recorded occasional above-average spikes in fall rainfall in the last decade. Further accumulation of data throughout the coming years will shed light on the significance of the rainfall floods, and trends in their timing & magnitude. I should note that not all physiographic regions in Canada that have bimodality have the second, lesser, rainfall-induced one in the autumn months. Rather, some regions, most notably the prairie provinces, have the rainfall-induced flooding in the summer months due to convective storms.<br />
<br />
<b>What are the take-home messages?</b><br />
<br />
There are many implications for the decreasing snowpack melt, and how it interacts with certain <a href="http://en.wikipedia.org/wiki/Biogeochemical_cycle">biogeochemical cycles</a>. Particular regions of Canada rely on the spring melt to supply freshwater, and in BC, hydroelectric power will be adversely affected by a decrease in discharge at certain expected intervals. You've likely seen the news on how floods in Manitoba have adversely impacted populations living in flood plains there, but that has more to do with latitude, topography and a South - North sloping drainage basin (<a href="http://geoearth.uncc.edu/people/ajefferson/">Anne Jefferson</a> at <a href="http://all-geo.org/highlyallochthonous/">Highly Allochthonous</a> has a great <a href="http://all-geo.org/highlyallochthonous/2011/04/why-does-the-red-river-of-the-north-have-so-many-floods/">post on the topic</a>). Ongoing changes in the timing and magnitude of spring floods are not restricted to a particular flood seasonality type, but rather occur across Canada in different climatic and hydrologic regimes. Ultimately, the paper highlights that trends in the magnitude of floods are more pronounced than trends in the timing of floods, and the changes in magnitude are having a great impact among natural systems connected to the melting of the snowpack in the spring.<br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg4gAhFZWfbTpOjKdT-x4ecGESEVFU4529Zvwx1zYyA5ToD3NCYKYH0bn2CCmm3UokL8mhjqP2AaB1tNdAakh8HqDAh_43wI75tHUGQX90DnhXnfoHjMG7VsNeL7zHZW5ctCLuWkvqk590/s1600/hydrosphere.jpg" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg4gAhFZWfbTpOjKdT-x4ecGESEVFU4529Zvwx1zYyA5ToD3NCYKYH0bn2CCmm3UokL8mhjqP2AaB1tNdAakh8HqDAh_43wI75tHUGQX90DnhXnfoHjMG7VsNeL7zHZW5ctCLuWkvqk590/s1600/hydrosphere.jpg" /></a>Additional Info: <b></b><br />
<ul><li> <a href="http://www.sciencedirect.com/science/article/pii/S0022169409003874">Juraj Cunderlik and Taha Ouarda - Trends in the timing and magnitude of floods in Canada</a></li>
<li><a href="http://www.bellacoolablog.com/2010_09_01_archive.html">Bella Coola Blog - September 2010</a></li>
<li><a href="http://www.ec.gc.ca/rhc-wsc/default.asp?lang=En&n=4EED50F1-1">Water Survey of Canada</a></li>
<li><a href="http://pubs.usgs.gov/twri/twri4a3/">USGS - Statistical Methods in Water Resources</a><br />
</li>
</ul>Malcolm V Lhttp://www.blogger.com/profile/00126268490488546890noreply@blogger.com1tag:blogger.com,1999:blog-2188731877707108811.post-10086022510036353012011-05-23T09:01:00.000-07:002011-05-23T09:01:08.622-07:00Accretionary Wedge #34: That is Weird<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj34A9ReEU092cua9uRWwRPmZZb_sLIJHHiukjSSz2hkGwcO1nM-BdQGqVOlng8pWQY8h2xSQAfeBs2VeiwbT4KZMCAmeisDBjbLhQjA2QIJR6XzLdvX3wJrmGwYXgdg8TxX0iZF9TNrq4/s1600/2816089459_fb12acaf83_o.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="338" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj34A9ReEU092cua9uRWwRPmZZb_sLIJHHiukjSSz2hkGwcO1nM-BdQGqVOlng8pWQY8h2xSQAfeBs2VeiwbT4KZMCAmeisDBjbLhQjA2QIJR6XzLdvX3wJrmGwYXgdg8TxX0iZF9TNrq4/s640/2816089459_fb12acaf83_o.jpg" width="550" /></a></div>This months <a href="http://theaccretionarywedge.wordpress.com/">Accretionary Wedge</a> is being hosted by Dana Hunter over at <a href="http://entequilaesverdad.blogspot.com/2011/05/accretionary-wedge-34-last-call-for.html">En Tequila Es Verdad</a>, which Google translates as "In Tequila is Truth" (don't ask this teetotaler what that means). The theme is any geology which the blogger considers weird. My limited experience means many geological phenomena I observe are initially head-scratchers, but subsequent investigation usually becomes a learning experience, and later I can't imagine a time before understanding the phenomenon.<br />
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<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjGgwNGojUT1RacYgr5rCUyv6w_iQo8JqPbbLIOZ80r_jhOHH4uSfB8KIOc4SKpu7h3uuk83CHkknDyVuBAurE7fMpvw3q9f7KDcGqZJni25rJ2xQDvDHh34C1_2u3FDn9d_SnBNHL1ZVg/s1600/3460446226_cef164e649_o.jpg" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" height="181" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjGgwNGojUT1RacYgr5rCUyv6w_iQo8JqPbbLIOZ80r_jhOHH4uSfB8KIOc4SKpu7h3uuk83CHkknDyVuBAurE7fMpvw3q9f7KDcGqZJni25rJ2xQDvDHh34C1_2u3FDn9d_SnBNHL1ZVg/s200/3460446226_cef164e649_o.jpg" width="200" /></a></div>In choosing what to post about that's weird, a memory popped into my head that quickly settled the issue. What better to include in this carnival on weird geology than a landform that has no unifying theory on its origin, but rather a bunch of hypotheses? What I speak of is the <a href="http://en.wikipedia.org/wiki/Mima_mounds">Mima Mounds</a>, located 20km south of <a href="http://en.wikipedia.org/wiki/Olympia,_Washington">Olympia, Washington</a>. This set of mounds is the only I have visited, but variations of Mima Mounds exist elsewhere: Lake District in Oregon, Northern China, and in the Western Sahara, to name a few. The geographic and climatic spread means that certain groups of the mounds have more explanation for their genesis, ex. the Oregon-based mounds have a more definitive volcanic morphology. But the mounds in Washington I'm focusing on continue to baffle geologists. Hypotheses about their origin range from animal construction - seismicity - periglacial kettle topography.<br />
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The mounds outside Olympia measure around 5-8 feet in height, and 12-20 feet in rough diameter. They are similar to the prairie-based <a href="http://www.projectpast.org/gvogel/uafpm/resources.html">pimple mounds of the southern Midwest states</a>, and their might be connections based on pedological similarities. If you are a keen geologist, each explanation will stir up good probing questions, many of which are yet to be answered fully. For instance, the gopher proposal is criticized for lack of zoological evidence at the Washington Mima Mounds, plus their density raises questions of competition for food resources if a multitude of gophers built them, or necessity if many mounds were built by a few gophers. The earthquake hypothesis is a compelling one, and more research into the physics of the mounds' granular material should be revealing once it comes forth.<br />
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgRHvAGph77zn6w_Zt1nWH6nC7lpNXNhD6bbeCoAOnTgHBYZgh0B3Q4k53JeP8Lo75e8vczwEyZ1ZWa7Zzpw7rHnfSUu6N0mFN2mNg6XWAU9ygx-abr6uWl3DC3SCqI-NmtgeWmU03lkkA/s1600/picturemt.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="349" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgRHvAGph77zn6w_Zt1nWH6nC7lpNXNhD6bbeCoAOnTgHBYZgh0B3Q4k53JeP8Lo75e8vczwEyZ1ZWa7Zzpw7rHnfSUu6N0mFN2mNg6XWAU9ygx-abr6uWl3DC3SCqI-NmtgeWmU03lkkA/s640/picturemt.jpg" width="550" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Click for larger version and read about the different hypotheses scientists have for the origin of the mounds.<br />
Info board courtesy <span class="citation web">Washington State Department of Natural Resources</span></td></tr>
</tbody></table><div style="font-weight: normal; margin-bottom: 0.5cm;">Most current research into the Mima Mound phenomena is concentrated around the periglacial hypothesis: Kettle & Kame topographical depressions (sun cups) were filled with glacial sediment during rapid retreat at the end of the last Ice Age. Repeated outburst floods as the glacial front retreated & disintegrated provided sediment that filled the depressions. Those depressions experienced subsequent freeze-thaw heave; hence they are arguably akin to small-scale <a href="http://en.wikipedia.org/wiki/Pingo">pingo</a> formations. However, glacial conditions are not apparent at several places where the mounds exist, even when examining deep-time paleogeography. Also of note is that not all mound formations have the same soil/sediment profile, even within the same mound group. Some of my own quick observations at the <a href="http://www.dnr.wa.gov/ABOUTDNR/MANAGEDLANDS/Pages/amp_na_mima.aspx">Mima Mounds Natural Area</a> include how the mounds are more diversely vegetated, some mounds have a deflated appearance, and that exposures of the substrate revealed a primarily gravelly/pebbly mixture that reminded me of glacial <a href="http://en.wikipedia.org/wiki/Diamicton">diamicton</a>.<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhkZx6sojcXyqegyeCAHzPL5re8f-s6jQY4neNMu2Wrz8Oawu4qJyBqfWRm3klyadWpEM4PMwNXRcP-zh80rkx20jfRkan5TB2A2Yn7FRgovK435UyPrUPIRt3SJI8UO7h37w9McxausDk/s1600/2008975537.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="146" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhkZx6sojcXyqegyeCAHzPL5re8f-s6jQY4neNMu2Wrz8Oawu4qJyBqfWRm3klyadWpEM4PMwNXRcP-zh80rkx20jfRkan5TB2A2Yn7FRgovK435UyPrUPIRt3SJI8UO7h37w9McxausDk/s640/2008975537.jpg" width="500" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Washington DNR LIDAR image of Mima Mounds (left) with matching Google Earth image (right) <br />
Site is near Littlerock, Wa. (46° 53.273'N 123° 3.054'W) </td></tr>
</tbody></table>Geology that can be considered 'weird' is refreshing to have around. A lot of it is nature's abstract art. I considered doing the <a href="http://en.wikipedia.org/wiki/Tessellated_pavement">tessellated pavement</a> structure of Eaglehawk Neck in Tasmania, but that has a thorough explanation, and honestly, when thinking of strange geological formations, one's that are unexplained and/or under debate strike my fancy more. Finding out that not everything in earth science is yet definitive gives me a chance, albeit small, to be a future pioneer.</div><div style="font-weight: normal; margin-bottom: 0.5cm;"><span style="font-family: Times New Roman,serif;"></span></div><div class="separator" style="clear: both; text-align: center;"></div><div class="separator" style="clear: both; text-align: center;"></div><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgZmZ1IXq4qS2AJJBmYRm9ANlCS3nY0-vM7bvhlDGS0TDcLleabhNaBFOxOmHTDW6QXI4vhNrhqyln7JUDLXaUlAO1fw8gFQCxIQW46tqvzZLBvBuBjfXhjHhXTxYzfx5FBmry0mmSAdWU/s1600/lithocryo.jpg" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgZmZ1IXq4qS2AJJBmYRm9ANlCS3nY0-vM7bvhlDGS0TDcLleabhNaBFOxOmHTDW6QXI4vhNrhqyln7JUDLXaUlAO1fw8gFQCxIQW46tqvzZLBvBuBjfXhjHhXTxYzfx5FBmry0mmSAdWU/s1600/lithocryo.jpg" /></a>Additional Info:<br />
<ul><li> <a href="http://seattletimes.nwsource.com/html/localnews/2008976743_mounds03m.html">Seattle Times - Laser mapping may help solve the mystery of the Mima Mounds</a></li>
<li><a href="http://en.wikipedia.org/wiki/Mima_mounds#Theories">Wikipedia entry on the various mound genesis hypotheses </a></li>
<li><a href="http://www.googleearthanomalies.com/Anomalies/CircularFeatures/MimaMounds/tabid/62/Default.aspx">Google Earth Anomalies - Mima Mounds worldwide</a></li>
<li><a href="http://www.perigeezero.org/treatise/Enigmas/geologic/mima_mounds/index.html">Perigee: Zero - Mima Mounds and similar landforms</a></li>
</ul>Malcolm V Lhttp://www.blogger.com/profile/00126268490488546890noreply@blogger.com3tag:blogger.com,1999:blog-2188731877707108811.post-29541234983321493832011-05-17T09:27:00.001-07:002011-05-22T23:39:23.942-07:00Field photo Set #3A recent stopover in <a href="http://en.wikipedia.org/wiki/Princeton_%28BC%29">Princeton, BC</a> gave me an opportunity to sidetrack to a couple interesting outcrops that expose sedimentary strata of different formations. It was a perfect day - clear skies, temps in the high teens, dry but not too dry - summer come early. Without even trying, on occasion I was within meters of adventurous local wildlife - a <a href="http://imageshack.us/m/833/4785/picture003tq.jpg">beaver</a>, several <a href="http://imageshack.us/m/535/554/picture004mhz.jpg">deer</a>, and a young black bear.<br />
<br />
One particular exposure along the <a href="http://www.tctrail.ca/home.php">TCT</a>, nicknamed the "Red Ochre Bluffs" because they were used by natives to create red pigment, is particularly interesting for its very reddish color, due to a high % content of the mineral <a href="http://en.wikipedia.org/wiki/Hematite">haematite</a> (iron oxide) within the bedded chert. Technically it is an outcrop of the Vermillion Bluffs shale member, part of the <a href="http://www.empr.gov.bc.ca/Mining/Geoscience/PublicationsCatalogue/Papers/Pages/1983-3.aspx">Allenby formation</a> of the Eocene epoch (45-50 Ma). This is a fossiliferous member, where fossils of maple, alder, fir, pine, dawn redwood and ginko have been found, along with one of the world's oldest fossilized bees. There is a noticeable dip to the beds of about 10°, striking NNE-SSW.<br />
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjpnDdduRI73MjR4eUmUtEST00fPLlEuvCZC8Z7tI32Zy3hbeSG0GmWbKCMkEM73eFyDIUF7Fjqeki-HwN7YmsaMjO-XR1PnoLhVeoIyhQufgBQ2SvWIwtwSpzqI4EOSJom1Pma9XaA8zE/s1600/Vermillion+Bluffs+shale.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="244" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjpnDdduRI73MjR4eUmUtEST00fPLlEuvCZC8Z7tI32Zy3hbeSG0GmWbKCMkEM73eFyDIUF7Fjqeki-HwN7YmsaMjO-XR1PnoLhVeoIyhQufgBQ2SvWIwtwSpzqI4EOSJom1Pma9XaA8zE/s640/Vermillion+Bluffs+shale.jpg" width="550" /></a></div><hr />At another part of Princeton, behind a small restaurant, is the only exposure in Princeton of the Summer Creek sandstone member of the Allenby formation:<br />
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhsObujtBfjltIz-40l2a6vrueEm3eL9ur0TLpfNvgaf2KZAEILxcNtedhPPBRWFqXwpQrCSZUg7R3uNDnD6Sl8eG5GCEeLoJrdwPW-lbZwyD_DDfBboVw0SUVnrelhkV_jJV5r1XZ9IcA/s1600/summersandstone.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="201" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhsObujtBfjltIz-40l2a6vrueEm3eL9ur0TLpfNvgaf2KZAEILxcNtedhPPBRWFqXwpQrCSZUg7R3uNDnD6Sl8eG5GCEeLoJrdwPW-lbZwyD_DDfBboVw0SUVnrelhkV_jJV5r1XZ9IcA/s640/summersandstone.jpg" width="550" /></a></div>A keen eye will notice the concretions, the cross laminations, and an apparent conglomerate boulder 'xenolith' that became part of the package, though it might be a beaten up granite-family rock. The sandstone layers have an approximate dip of 25°, and a strike of E-W. The member is mantled by a foot of glacial till (Princeton has a few kettle lakes of interest that showcase glacial geomorphology). This sandstone is some of the toughest I've felt; the layers are highly compacted and the presence of plenty of cementing material makes it a strong variant.<br />
<br />
The Vermillion Bluffs exposure can be found @ 49° 26.695'N 120° 32.665'W, after a 2km walk along the TCT. Part of the walk goes through a long tunnel where you can practice your bet megalomaniacal laugh.<br />
The Summer Creek sandstone rockface can be found @ 49° 27.313'N 120° 30.646'W, behind Billy's Family restaurant, where you can park and take a look at how First Nations hollowed out a cave within the sandstone to store plunder.<br />
<br />
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjloSOn-6xuJ6D2cillA1G6D9a9FY0iTHqY9fO48AikcLsSDoymkbddzXR2o-QS6qRII7bAp7g31XJWaheeH_nIC4LU4Zyqs4nucoNMoizS-slCvizM617gY_8x5q555PHmC9MkV_D-Ymk/s1600/litho.jpg" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjloSOn-6xuJ6D2cillA1G6D9a9FY0iTHqY9fO48AikcLsSDoymkbddzXR2o-QS6qRII7bAp7g31XJWaheeH_nIC4LU4Zyqs4nucoNMoizS-slCvizM617gY_8x5q555PHmC9MkV_D-Ymk/s1600/litho.jpg" /></a>Additional Info:<br />
<ul><li><a href="http://www.hellobc.com/en-CA/SightsActivitiesEvents/AirLandActivities/Hiking/Princeton.htm">Super Natural BC - Princeton Hiking</a></li>
<li><a href="http://fossilhuntress.blogspot.com/2008/04/ancient-treasure-from-vermillion-bluffs.html">Archea (Fossil Huntress) - Fossils and Red Ochre</a> </li>
<li><a href="http://www.empr.gov.bc.ca/Mining/Geoscience/PublicationsCatalogue/GeoFiles/Pages/2000-10.aspx">N.W.D Massey - Geological Compilation of the Similkameen Coal Basins, Southwestern BC: Tertiary Geology</a><br />
</li>
</ul>Malcolm V Lhttp://www.blogger.com/profile/00126268490488546890noreply@blogger.com0tag:blogger.com,1999:blog-2188731877707108811.post-20250878610324581142011-05-13T14:23:00.000-07:002011-05-13T14:23:39.616-07:00Looking through the archives: Melbourne's climate<div style="margin-bottom: 0cm;"><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEij4N6lu2WkAHH0z47eL9rZRWvTXipS7qBweWPr9CmZ2ZeuCv3MbS6iMgWz_yt3ROlYdmD8JO16X4Dpf1z2bmeOq-skZrJaafL5isQaklIRPvMbOwqWWVUQ2PW2afoX9VItg8LWRDUv2Qo/s1600/mel2009bfires.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="364" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEij4N6lu2WkAHH0z47eL9rZRWvTXipS7qBweWPr9CmZ2ZeuCv3MbS6iMgWz_yt3ROlYdmD8JO16X4Dpf1z2bmeOq-skZrJaafL5isQaklIRPvMbOwqWWVUQ2PW2afoX9VItg8LWRDUv2Qo/s640/mel2009bfires.png" width="550" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Satellite image of pyrocumulus clouds over Victoria & New South Wales, <br />
taken by NASA's Aqua satellite in early February 2009</td></tr>
</tbody></table>The climate of Melbourne, Victoria, Australia is one of great variation relative to the rest of the continent, but still moderate as oceanic effects and broad relief limit extremes, especially in terms of freezing temperatures and excessive rainfall. The city is located at the south-central side of the state of Victoria, which is the southeast corner of Australia. With a Latitude/Longitude of 37.5°S 145.0°E, Melbourne falls within what is technically considered the mid-latitude region. In terms of global circulation patterns, the city is affected by not only <a href="http://en.wikipedia.org/wiki/Westerlies">mid-latitude westerlies</a>, which brings air across the west of the continent to the city, but also by the <a href="http://en.wikipedia.org/wiki/Subtropical_high">subtropical High</a> and the Antarctic circumpolar vortex. The subtropical High normally resides in New South Wales for most of a typical year, but during the southern hemisphere summer the <a href="http://en.wikipedia.org/wiki/ITCZ">ITCZ (Intertropical Convergence Zone)</a> descends into northern Australia, thus pushing the subtropical High south into Victoria and Melbourne. These seasonally changing patterns make Melbourne a diverse region in terms of weather, and fosters extreme events such as bushfires & droughts that are amplified by <a href="http://en.wikipedia.org/wiki/El_nino">El Niño southern oscillations</a>.</div><div style="margin-bottom: 0cm;"><br />
</div><div style="margin-bottom: 0cm;"></div><div style="margin-bottom: 0cm; text-decoration: none;"><span style="font-size: small;"><b>Melbourne at a Glance</b></span></div><div style="margin-bottom: 0cm;"><br />
</div><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjrpqA83i3Fk4W3foonXGlcNVzgKOyt4Z1RbPv14JhA5POkQdkCH1QcbRVBRvWXBuCe0FlkSOLENBuTBUNNqSJZDjNh-QrqfMKt8Y3DAA7c0_Z3cURcAPrt8kuLxq74c4XXowReaAO9iOg/s1600/melbmap.png" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" height="200" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjrpqA83i3Fk4W3foonXGlcNVzgKOyt4Z1RbPv14JhA5POkQdkCH1QcbRVBRvWXBuCe0FlkSOLENBuTBUNNqSJZDjNh-QrqfMKt8Y3DAA7c0_Z3cURcAPrt8kuLxq74c4XXowReaAO9iOg/s200/melbmap.png" width="199" /></a></div><div style="margin-bottom: 0cm;">Melbourne lies quite flat on the horizon. A coastal city of 4 million with a secluded port as its access to the Indian Ocean (via <a href="http://en.wikipedia.org/wiki/Bass_strait">Bass Strait</a>), Melbourne is at the confluence of two major rivers that flow into <a href="http://en.wikipedia.org/wiki/Port_Philip">Port Philip</a> (<a href="http://en.wikipedia.org/wiki/Yarra_River">Yarra</a> and <a href="http://en.wikipedia.org/wiki/Maribyrnong_River">Maribyrnong</a>). Geologically, Melbourne is mostly underlain by <a href="http://en.wikipedia.org/wiki/Silurian">Silurian</a> marine sediments, and modern alluvium from Yarra. The marine sediments were uplifted from the shallow Bass Strait. This highlights how low the general relief of southern Victoria is. With a sea level decrease of just 70m, a land bridge would form between the city and the island of Tasmania.</div><div style="margin-bottom: 0cm;"><br />
</div><div style="margin-bottom: 0cm;">In terms of precipitation, this low relief makes Melbourne susceptible to flash flooding during more intense showers/thunderstorms in both <a href="http://en.wikipedia.org/wiki/La_nina">La Niña</a> and spring seasons. Poor drainage and infiltration through city streets, combined with a low greenspace ratio, exacerbate flash floods in the city.</div><div style="margin-bottom: 0cm;"><br />
</div><span style="font-size: large;"><a href="http://pumicecastle.blogspot.com/p/looking-through-archives-melbournes.html">Click to read more... </a></span>Malcolm V Lhttp://www.blogger.com/profile/00126268490488546890noreply@blogger.com0tag:blogger.com,1999:blog-2188731877707108811.post-28728761426361054662011-05-09T06:45:00.000-07:002011-05-09T06:45:29.718-07:00USGS and GISI can't stand acronym overload, but lately I've been caught overusing them. Yesterday a discussion about construction at a park and the info they put up about ephemeral streams resulted in me using 'WRC', 'CWH' and 'BFR' to the befuddlement of my friend. But in the case of this blog, I can't imagine anyone reading it not grasping the two acronyms in this posts title.<br />
<br />
Many of the earth science/physical geography professors and grad students I've talked to are almost unanimous in enjoying the field work aspect of their research. However, some of them are apprehensive about GIS technology, believing that increased ubiquity of the software will reduce or even eliminate the need for hard data gathering that is a big part of field work. Is that true? I don't know. I can surmise that depending on circumstances it could be, and I've certainly been to a few <a href="http://en.wikipedia.org/wiki/Geomatics">geomatics</a> presentations where the crux of a new technique is to gather empirical geographic data without leaving the desk.<br />
<br />
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiRTI5AlNYvSDdOnOBDAr9CMD7UdUZk4xuXt-9gTdEcNW5l5SFfQRA22rjePo_CwDjjwUQEVCjP9sMKtsxpbi5dMvX9ZOJA4b2qiYXByEDQNFdLBEk5YYwhhC0b4fOttU29skaoaw8zD3Y/s1600/picard-facepalm.jpg" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" height="210" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiRTI5AlNYvSDdOnOBDAr9CMD7UdUZk4xuXt-9gTdEcNW5l5SFfQRA22rjePo_CwDjjwUQEVCjP9sMKtsxpbi5dMvX9ZOJA4b2qiYXByEDQNFdLBEk5YYwhhC0b4fOttU29skaoaw8zD3Y/s320/picard-facepalm.jpg" width="320" /></a></div>However, good GIS data is hard to find, and free GIS data even harder. Our own Geological Survey does not release much data to the public for free, and finding any GIS digital elevation model (<a href="http://en.wikipedia.org/wiki/USGS_DEM">DEM</a>) files is akin to a needle-in-haystack search. So I was surprised when looking up information on Crater Lake and stumbling across USGS's collection of DEM files on the lake's bathymetry. Scratch that ... I wasn't surprised, as I've gotten used to the ridiculous restrictions my own government places on what should be freely available public information (these restrictions aren't limited to the geographic realm). One of my GIS bosses remarked on how his students are finding it really hard to collect digital data for their term projects, and he further mentioned that most projects involve analysis of geographic phenomena in BC. Even my own work projects involving examinations of local watersheds was shelved due to lack of <a href="http://en.wikipedia.org/wiki/Shapefile">shapefiles</a> or anything that could be converted to such without a lifetime of eye damage.<br />
<br />
But is the USGS stuff I found really any good? Cracking open <a href="http://www.esri.com/software/arcgis/index.html">ArcGIS</a> to take a look at the bathymetry data, I was immediately struck with déjà vu. Where had I seen this layout of Crater Lake before? Of course, I see a variation of it in passing everyday, pinned up on my apartment wall: <br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiaUqcBTi7EvqGTM9nXJlBLNTH6meLFKM_Dcsyk4x9r4LM8D-7E7zAm94dGa4hiRKOFppHPawoPG9h7XhveItNtTprU1FLWZIHwoKqX1lZneoxOTZxGwE7TCXsrPUGSiCwr1iuMCz_vsyk/s1600/craterlakebathy.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="563" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiaUqcBTi7EvqGTM9nXJlBLNTH6meLFKM_Dcsyk4x9r4LM8D-7E7zAm94dGa4hiRKOFppHPawoPG9h7XhveItNtTprU1FLWZIHwoKqX1lZneoxOTZxGwE7TCXsrPUGSiCwr1iuMCz_vsyk/s640/craterlakebathy.png" width="500" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">At a gift shop in Crater Lake park, there was a huge 6-foot tall version of the above geologic map with even more detail. Alas, it was only for display, but the 4-foot tall version available for customers has good detail for a pretty penny.</td></tr>
</tbody></table>I was able to do lots with the data, modifying it, adding annotations, creating a color scheme for entities, and segmenting portions of Crater Lake geology using primitives as splitters. Using the data in <a href="http://www.esri.com/news/arcnews/summer03articles/introducing-arcglobe.html">ArcGlobe</a> was especially interesting, as you get a true sense of scale and perspective for all the features above & below lake level because you can strip away the water with a click. Some of the diagrams I've seen in Crater Lake academic papers have definitely used these DEM files. The resolution is incredible, as the 2000 bathymetric survey conducted by USGS, NPS, and University of New Hampshire's <a href="http://www.ccom-jhc.unh.edu/">CCOM</a> used multibeam acoustic sounders that translated data to a 2-meter-per-pixel representation factor.<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjYUTLSk7NgCMvf8zxTN6QKFVvpfWuUW8Ipow4xiMJe8CihojJPSKtGAk7jDGqmoW3Ynp3Dxgk81TPe4QBIWx-CgOtNUBSIVxZglEkl8IDea-aqYC-OF4AHxNaf0Tmr5_AtGkBDN95lsFM/s1600/CraterlakeGlobe.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="357" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjYUTLSk7NgCMvf8zxTN6QKFVvpfWuUW8Ipow4xiMJe8CihojJPSKtGAk7jDGqmoW3Ynp3Dxgk81TPe4QBIWx-CgOtNUBSIVxZglEkl8IDea-aqYC-OF4AHxNaf0Tmr5_AtGkBDN95lsFM/s640/CraterlakeGlobe.png" width="550" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">The virgin view of Crater Lake in ArcGlobe [Top Left]. USGS 7.5 arcminute DEM of Crater Lake, showing shaded relief bathymetry [Top Right]. Angled perspective of 7.5 arcminute Crater Lake DEM, with annotated structures [Bottom] </td><td class="tr-caption" style="text-align: center;"></td></tr>
</tbody></table>Thank goodness for the USGS! Good physical geography GIS data is out there, based on surveys they've conducted, and data they digitized. Best of all, it's freely available to the public. Now if only my federal government would allow GSC to follow suit.<br />
<hr /><div style="text-align: center;"><span style="font-size: large;"><u><b>On the subaqueous features/structures of Crater Lake</b></u></span></div><div style="text-align: left;"><span style="font-size: large;"><u><b> </b></u></span></div><div style="text-align: left;"><br />
<b>Rhyodacite Dome</b> = youngest (5 Ka), shallowest subaqueous feature. It is a highly silicic lava dome that has formed from a vent that intruded through both the andesitic Central Platform & the eastern flank of Wizard Island. Rhyodacitic flows and domes were common in Mazama's history between 40-5 Ka.<br />
<br />
<b>Central Platform</b> = Subaerial andesite flows that experienced <a href="http://www.tulane.edu/%7Esanelson/geol212/magmadiff.htm">magma differentiation</a> from within the primary chamber. Successive eruptions (7-6 Ka) that built up the platform were above lake level, giving the platform a low, broad relief until flows met the old shoreline.<br />
<br />
<b>Merriam Cone</b> = Cinder cone whose lower portion/foundation was formed as a <a href="http://en.wikipedia.org/wiki/Resurgent_dome">resurgent dome</a>, composed of subaqueous andesite, formed from completely submarine eruptions circa 7.7-7.5 Ka. It has a nearly geometrically idealized cone shape. Peak is ~150m below current lake level. Origins and formation still not agreed upon (Resurgent dome or Cinder cone or how much of a combination??). <br />
<br />
<b>Phantom Ship</b> = Oldest (400 Ka), partially subaqueous feature. Considered to be the top of a basic-andesitic volcanic dike, a remnant of a small vent that might have fed <a href="http://en.wikipedia.org/wiki/Parasitic_cone">parasitic cones</a> on pre-cataclysmic Mazama's eastern flank (see also <a href="http://www.craterlakeinstitute.com/natural-history/geology-devils-backbone.htm">Devil's Backbone</a>).<br />
<br />
<b>Various Depositional Basins</b> = Colluvium, volcaniclastics, volcanic breccia, and ash particles, all weathered and transported to the low-lying depressions of the caldera. The rim has plenty of talus slopes. There is a huge landslide deposit on the southern end of the lake, called the <a href="http://www.swisseduc.ch/stromboli/perm/cl/landslide-en.html">Chaski Bay landslide</a>, with a debris avalanche volume of 0.1 km<sup>3</sup> (couldn't find an exact date on the slide). Evidence of the slide triggering a mild tsunami is found at Cleetwood Cove on the northern end.<br />
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<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgmm_ek4UhJmo3Z2lLDw_kI3O2LKqORLkUkW_FMG_4ktu_iV6VsWaf522uRm4kBypRBeaG6ABPDuwbvClTxdfXC6FBi-ohWZYeCx6qSHnv5sTmc7qmQfPjy-QHjkYA-qIj4qG9jxRLlqO8/s1600/twospheres.jpg" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgmm_ek4UhJmo3Z2lLDw_kI3O2LKqORLkUkW_FMG_4ktu_iV6VsWaf522uRm4kBypRBeaG6ABPDuwbvClTxdfXC6FBi-ohWZYeCx6qSHnv5sTmc7qmQfPjy-QHjkYA-qIj4qG9jxRLlqO8/s1600/twospheres.jpg" /></a></div>Additional Info:<br />
<ul><li><a href="http://oe.oregonexplorer.info/craterlake/">Oregon Explorer - Crater Lake Data Clearinghouse</a></li>
<li><a href="http://pubs.usgs.gov/fs/2002/fs092-02/">USGS - Mount Mazama and Crater Lake: Growth and Destruction of a Cascade Volcano</a></li>
<li><a href="http://walrus.wr.usgs.gov/pacmaps/cl-shd.html">USGS - Seafloor Mapping: Crater Lake shaded relief </a></li>
<li><a href="http://pubs.usgs.gov/dds/dds-72/site/merrm.htm">USGS - Merriam Cone Perspective View</a></li>
<li><a href="http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6V61-4FVH4HR-2&_user=10&_coverDate=05%2F15%2F2005&_rdoc=1&_fmt=high&_orig=gateway&_origin=gateway&_sort=d&_docanchor=&view=c&_searchStrId=1744137350&_rerunOrigin=google&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=827b1dd16c66fa297afa3f92c97fc71d&searchtype=a">Charles Bacon et al. - Late Pleistocene granodiorite source for recycled zircon and phenocrysts in rhyodacite lava at Crater Lake, Oregon</a></li>
</ul><ul></ul></div><div class="separator" style="clear: both; text-align: center;"></div>Malcolm V Lhttp://www.blogger.com/profile/00126268490488546890noreply@blogger.com2tag:blogger.com,1999:blog-2188731877707108811.post-24227737877744024812011-05-03T08:41:00.001-07:002011-05-03T08:45:14.261-07:00Columbia Basin Trip: Day 3 - McCall and a bunch of Falls<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg6Vl3Tvt6v1UHkNoSEjXcrNXchSSeJzGzlZ3F8kJmDWrLXPsF1zm3vvj0UvBjur0rOcmePeUl09NJP-yxZuz0RUN4xYEXw9f-Fr7rBvNq0eFBZqe9ldGFcd1YPzoM9TChWxSAPjhvjtKU/s1600/Picture+088.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="350" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg6Vl3Tvt6v1UHkNoSEjXcrNXchSSeJzGzlZ3F8kJmDWrLXPsF1zm3vvj0UvBjur0rOcmePeUl09NJP-yxZuz0RUN4xYEXw9f-Fr7rBvNq0eFBZqe9ldGFcd1YPzoM9TChWxSAPjhvjtKU/s640/Picture+088.jpg" width="550" /></a><br />
My third and final day out in Oregon included a spectacular hike through a nature preserve, and a drive along an historic highway where there is the greatest concentration of high waterfalls in the US. I lost count of how many waterfalls I saw, and recalling all their names is tough (Elowah, Oneonta, Multnomah, Horsetail, Ponytail, Latourell, Sheppard Dell, just to name a few). Each fall had its own character, in which the basalt rockfaces they flowed over varied in layering, formation, and vegetation.<br />
<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgTN-TEr-LWX3J1y0fczUxaNPMhp4ybDNR9ZOi8RX5jTZuOKaran3Gw7bVC91szVYXNZrusgN9_aVn3kOeor6h1V1L9SE7jCEEEeZ_DthvUaO0x_GdsnL-q2Cd3SuzqIgC2KjP5QxXZdcw/s1600/Picture+089.jpg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="200" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgTN-TEr-LWX3J1y0fczUxaNPMhp4ybDNR9ZOi8RX5jTZuOKaran3Gw7bVC91szVYXNZrusgN9_aVn3kOeor6h1V1L9SE7jCEEEeZ_DthvUaO0x_GdsnL-q2Cd3SuzqIgC2KjP5QxXZdcw/s200/Picture+089.jpg" width="191" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Info board @ Rowena Crest parking</td></tr>
</tbody></table><br />
But first, before the falls, it was time for a satisfying hike. <a href="http://www.amazon.com/Hiking-Oregons-Geology/dp/0898868475/ref=sr_1_1?ie=UTF8&s=books&qid=1304389535&sr=8-1">Hiking Oregon's Geology</a> guide book spoke of a 4-5 mile hike through a nature preserve just outside <a href="http://en.wikipedia.org/wiki/The_Dalles,_Oregon">The Dalles</a> (which I learned is pronounced "Dals", not "Dall-ehz"). Called the "Rowena Crest/Tom McCall Preserve", most of the geology relating to this hike is distant, observed by viewing the Columbia River gorge on the opposing Washington state side. Their side has the Ortley Pinnacles, fragments of basalt cemented together at a fault line. Mounds dotting the preserve's open stretches of grassland are erosional remnants of St. Helens ash deposits; they are more subdued and more sporadic than the infamous <a href="http://img545.imageshack.us/img545/2992/picturemt.jpg">Mima Mounds</a>, which may or may not have the same genesis. The real highlight of the hike is ecological, as at this point in springtime I could spot <a href="http://en.wikipedia.org/wiki/Lupin">lupines</a>, <a href="http://en.wikipedia.org/wiki/Balsamroot">balsamroot</a>, and blossom trees, and that was with my weaker-than-novice botanical background. The whole scene was very colorful at this time of year, and was capped off with sunny, turbulent weather.<br />
<hr /><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg1l73Xax3eNl__EZDWBVGMXwP_gbORMeq_f08KTQFyr4krxVPhPfWPlZa3XvfW0jG3spPjpmajft3H7zbYty-jHZ2k6YRbvqwfsLCeThpsWfbvez2IvQpRl_O45JLVd5I3_VlOW_6Alio/s1600/Picture+121.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="38" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg1l73Xax3eNl__EZDWBVGMXwP_gbORMeq_f08KTQFyr4krxVPhPfWPlZa3XvfW0jG3spPjpmajft3H7zbYty-jHZ2k6YRbvqwfsLCeThpsWfbvez2IvQpRl_O45JLVd5I3_VlOW_6Alio/s640/Picture+121.jpg" width="550" /></a></div>The bulk of the geology in Day 3 came in the form of neverending pullovers and short, grinding switchbacks to view a multitude of waterfalls. This collection of falls was created when the <a href="http://en.wikipedia.org/wiki/Missoula_Floods">Missoula floods</a> cut away the gentle foothills of the flood basalts, leaving the cliffs and their creeks-turned-falls. If my recollection is correct, all but two of the falls I visited were of the plunge variety (Oneonta was Step-Pool, Sheppard Dell was tiered/fan). Discharge was excellent, fueled by mid-spring rains and freshet melt from peaks ranging from 1200-1600m elevation (see above cross-section).<br />
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Two particular falls were a real treat to behold: Multnomah & Latourell. The former is the highest in Oregon, second highest in the continental US, and technically is a hybrid of plunge/step-pool, with a higher and lower set of falls. Differential cooling rates of the various Columbia flood basalt lava flows (<a href="http://en.wikipedia.org/wiki/Columbia_River_Basalt_Group#Grande_Ronde_Basalt">Grande Ronde Basalt</a>) provided Multnomah with distinctive layering from top-bottom. I could make out entablature basalt layers (fast cooling, fractured into irregular blocks & joints), a pillow basalt layer (fastest cooling when exposed to water, forming rounded cobbles), and columnar basalt layers (slower cooling under entablature, forming slender hexagonal blocks) at the very top and interspersed near the bottom behind the rockfall scarp. Multnomah Falls splashwater erodes softer layers of rock below & behind the falls, creating a plunge poll and amphitheater semi-cave. The higher falls recede upstream faster than the lower falls due to weaknesses in their lowest basalt layers. Large pieces of basalt rockface have historically been calved off, including a 400 ton piece falling into the plunge pool and drenching a wedding party 15 years ago.<br />
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjVGgof1jJQ72GM0BtMO99S0VYXcNLauoQJw0MluXFcvDgC2Y3xkHFUb2UIHIKVLXC7fADkBxRtkbg6ixSyuANT27P7LInhzLF8vfdzB6FY_rWmhBWog2KVEchw7OiMM9Xc6bp0XEkT-VU/s1600/Picture+098.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="266" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjVGgof1jJQ72GM0BtMO99S0VYXcNLauoQJw0MluXFcvDgC2Y3xkHFUb2UIHIKVLXC7fADkBxRtkbg6ixSyuANT27P7LInhzLF8vfdzB6FY_rWmhBWog2KVEchw7OiMM9Xc6bp0XEkT-VU/s640/Picture+098.jpg" width="500" /></a></div><blockquote><small>"... Observations of waterfalls over Columbia River basalt have shown that falls often occur where flows are flat lying or dipping upstream. This condition allows blocks produced by vertical joints to remain stable until support is withdrawn by erosion of softer interflow material at the base of individual flows. The rate of erosion of interflow areas probably largely controls the rate of retreat of the falls. The amphitheater-shaped valleys common to many of the falls within the Gorge are due to the freeze-thaw action of water from the splash mist that has penetrated the joints. ..." <span style="font-size: 10pt;">[Norman and Roloff, 2004]</span></small></blockquote><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="http://smg.photobucket.com/albums/v253/RavenessM/Geo/Blog/?action=view&current=Latfalls.mp4"></a><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjg80p6bHb84FUYfy61nsIAGlGLxjVnlfOIKqinar7x81tEeykYHvFiodjlTovKxt98MItRJp38x3aRvy8v4oc6CPkrK9u8T7wAGnoLG68tDdVwHAHpd0W0_m6jsCIjPe_O3hSYjK1i3O8/s1600/Picture+113.jpg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjg80p6bHb84FUYfy61nsIAGlGLxjVnlfOIKqinar7x81tEeykYHvFiodjlTovKxt98MItRJp38x3aRvy8v4oc6CPkrK9u8T7wAGnoLG68tDdVwHAHpd0W0_m6jsCIjPe_O3hSYjK1i3O8/s320/Picture+113.jpg" width="240" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Latourell Falls from the lower gallery<br />
<a href="http://smg.photobucket.com/albums/v253/RavenessM/Geo/Blog/?action=view&current=Latfalls.mp4">Click for short video of falls in action</a></td><td class="tr-caption" style="text-align: center;"><br />
</td></tr>
</tbody></table>Latourell Falls were nearly as impressive as Multnomah, and benefited from not having the trappings of tourism that's part of the Multnomah stop. Though not as high and not as layered, Latourell was pristine & photogenic, with lichen giving an entablature formation a splash of color, and the columns on the bottom undercut layer looking like an arrangement of cathedral organ pipes. The 76m plunge is the most unfettered of all high waterfalls in the gorge region, as others tend to impact (horsetail) at least slightly against the vertical rockface. It's one of those beauties where it's hard to take a bad picture.<br />
<br />
<div style="margin-bottom: 0cm;">I'm not really good with coda's, but I can say that there is one dominant feeling I came away with from this trip = I want to go again...but somewhere new. And as gas prices continue their northward march, the western US states are looking even more preferable than they were beforehand. I certainly got to experience a huge slice of basalt geology, which was quite the contrast from the granite geology of my home base. I think the next time calls for a true desert locale, something not really available in my home province (<a href="http://en.wikipedia.org/wiki/Osoyoos">Osoyoos</a> doesn't count). Ahh the possibilities...I just wish they wouldn't butt up against the lack of time & money.<br />
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Additional Info:<br />
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgmm_ek4UhJmo3Z2lLDw_kI3O2LKqORLkUkW_FMG_4ktu_iV6VsWaf522uRm4kBypRBeaG6ABPDuwbvClTxdfXC6FBi-ohWZYeCx6qSHnv5sTmc7qmQfPjy-QHjkYA-qIj4qG9jxRLlqO8/s1600/twospheres.jpg" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgmm_ek4UhJmo3Z2lLDw_kI3O2LKqORLkUkW_FMG_4ktu_iV6VsWaf522uRm4kBypRBeaG6ABPDuwbvClTxdfXC6FBi-ohWZYeCx6qSHnv5sTmc7qmQfPjy-QHjkYA-qIj4qG9jxRLlqO8/s1600/twospheres.jpg" /></a></div><ul><li><a href="http://www.waterfallsnorthwest.com/nws/waterfall.php?num=1913">Northwest Waterfall Survey - Latourell Falls</a></li>
<li><a href="http://www.waterfallsnorthwest.com/nws/waterfall.php?st=&num=1923">Northwest Waterfall Survey - Multnomah Falls</a></li>
<li><a href="http://www.nature.org/ourinitiatives/regions/northamerica/unitedstates/oregon/placesweprotect/tom-mccall-preserve-at-rowena.xml">The Nature Conservancy - Tom McCall Preserve at Rowena</a></li>
<li><a href="http://geology.com/waterfalls/oregon.shtml">Map of Oregon Waterfalls</a></li>
<li><a href="http://www.sciencedirect.com.ezproxy.kwantlen.ca:2080/science?_ob=ArticleURL&_udi=B6V6J-4YPT1YB-1&_user=1898427&_coverDate=08%2F31%2F2010&_alid=1738303778&_rdoc=1&_fmt=high&_orig=search&_origin=search&_zone=rslt_list_item&_cdi=5816&_sort=r&_st=13&_docanchor=&view=c&_ct=172&_acct=C000055247&_version=1&_urlVersion=0&_userid=1898427&md5=cb944933ca9e21b622e7c47a2d47a78e&searchtype=a">T.L. Barry et al - New 40Ar/39Ar dating of the Grande Ronde lavas: Implications for duration of flood basalt eruption episodes </a></li>
</ul></div><div class="separator" style="clear: both; text-align: center;"></div>Malcolm V Lhttp://www.blogger.com/profile/00126268490488546890noreply@blogger.com2tag:blogger.com,1999:blog-2188731877707108811.post-46716894801668388132011-05-01T09:41:00.000-07:002011-05-01T09:41:21.528-07:00Columbia Basin Trip: Day 2 - Sisters along the Columbia<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj3A_tQtEasumzMQ5hKjfMh5-hS-4SMzZiSzlbqpn41jkPi42cf-Nux96TNjNRC3PDo6PCBk-R3ugfDkSGRte9xVWzeLWFHDG3_BDe9Tnr7cRSJg8VXbLT5Mg9pQrS37mWuMGV3dBe1sE8/s1600/Picture+063.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="340" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj3A_tQtEasumzMQ5hKjfMh5-hS-4SMzZiSzlbqpn41jkPi42cf-Nux96TNjNRC3PDo6PCBk-R3ugfDkSGRte9xVWzeLWFHDG3_BDe9Tnr7cRSJg8VXbLT5Mg9pQrS37mWuMGV3dBe1sE8/s640/Picture+063.jpg" width="550" /></a></div><div class="separator" style="clear: both; text-align: center;"></div>Looping around the <a href="http://en.wikipedia.org/wiki/Wallula_Gap">Wallula Gap</a> early the next morning, I made a stop at an interesting formation that at first makes me think 'volcanic plug'. Alas, the Twin Sisters are not so, but rather they are the erosion-resistant last vestiges of great flood basalts that covered this particular part of the Columbia Basin. The pillars, which are shaped like irregular molar teeth, consist of vertical remnants of pillow basalt atop a foundation of columnar basalt. Certainly there are other basalt forms in the Gap that also have bits of these remnants still standing, but the Sisters are the largest, most impressive, and least covered in vegetation. As you can see above, their interesting shape spurred native legends & provided some flavor to the geology.<br />
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjiTTWAXhxRe0Eq4wDqIdaUXrfuyISnR2Szwf0FqOEZq8DUehO-qezVHMXCZzjLdzI6dlIoh1SN-alj6BYyIf0o5vw6GOeRJZfAeWGHTS4_5CWi5T0qubHCYnp4OOMEohc-iJIwKvKqY50/s1600/Picture+070.jpg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjiTTWAXhxRe0Eq4wDqIdaUXrfuyISnR2Szwf0FqOEZq8DUehO-qezVHMXCZzjLdzI6dlIoh1SN-alj6BYyIf0o5vw6GOeRJZfAeWGHTS4_5CWi5T0qubHCYnp4OOMEohc-iJIwKvKqY50/s320/Picture+070.jpg" width="272" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Two distinct forms of basalt make up the Sisters</td></tr>
</tbody></table><br />
Every geoscience geek with the smallest bit of knowledge of Pacific Northwest geology knows of the <a href="http://en.wikipedia.org/wiki/Glacial_Lake_Missoula">Glacial Lake Missoula</a> floods and their offspring, the <a href="http://en.wikipedia.org/wiki/Channeled_Scablands">Channeled Scablands</a>. The Wallula Gap, its numerous flood basalt flows, and the Twin Sisters themselves were all shaped by the late Pleistocene floods that ultimately found their outlet down the Columbia River. Akin to the Umtanum anticline mentioned on <a href="http://pumicecastle.blogspot.com/2011/04/columbia-basin-trip-day-1-lahar-and.html">Day 1</a>, compression of the basalt layers created an anticlinal ridge in the Wallula Gap area. An ancient river, precursor to the modern Columbia, slowly but surely cut a gorge through the layers as the gradient increased. Thus we had another water gap created thanks to the steady pace of uplift matching erosion. Of course, once the Missoula outburst floods began, tremendous volumes of water swept down towards the Gap where they were constricted, and thus erosive power was mostly focused on widening the Gap. <br />
<br />
For those not familiar with the Scablands, their features & their origins: During the late Pleistocene, the <a href="http://en.wikipedia.org/wiki/Cordilleran_Ice_Sheet">Cordilleran ice sheet</a> advanced into northern Idaho, Montana, and Washington. Gigantic ice dams were formed behind lobes of the continental glacier, holding back thousands of cubic kilometers of meltwater. When these dams broke, huge amounts of water were unleashed, following the path of least resistance through eastern & central Washington, constricting at the Wallula Gap, then funneling down the Columbia River, creating the <a href="http://en.wikipedia.org/wiki/Columbia_River_Gorge">Columbia River gorge</a>. The last of the floods, called the <a href="http://en.wikipedia.org/wiki/J_Harlen_Bretz">Bretz flood</a>, released 1600 km<sup>3</sup> of water in a two-day period, inundating nearly the entire Channeled Scablands region, and even extended into the <a href="http://en.wikipedia.org/wiki/Willamette_Valley">Willamette River valley</a> south of Portland, before exiting into the Pacific near Astoria.<br />
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiWUoxqge2tzKRq3yosj0esvaTiqK4UEDNtPff1z5xKQ5GVOMI0wPZcusFpVcEdRMdY2PiQFQArvTFam-yc9_o25v4R1Ou60HQ00ZyXNvF-bTsEJSKzVy5WDbDFHjjYDtvrdeUxo4I0UkE/s1600/Map_missoula_floods.gif" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="369" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiWUoxqge2tzKRq3yosj0esvaTiqK4UEDNtPff1z5xKQ5GVOMI0wPZcusFpVcEdRMdY2PiQFQArvTFam-yc9_o25v4R1Ou60HQ00ZyXNvF-bTsEJSKzVy5WDbDFHjjYDtvrdeUxo4I0UkE/s640/Map_missoula_floods.gif" width="500" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Diagram of geographical interaction between Pleistocene ice sheets (blue), Glacial Lake Missoula (yellow), and the full extent of the Channeled Scablands (orange)</td></tr>
</tbody></table><div class="separator" style="clear: both; text-align: center;"></div><hr />I lingered at the Twin Sisters for quite some time on the quiet weekday morning, and I wandered around looking at various perspectives of the palisade basalt, those exposures of basalt along ridges that make it look as if the area is fortified. Ahead of me was a long drive westward on the Columbia River interstate highway, made longer by tough crosswinds picking on my little Yaris. I didn't get to witness or scrutinize much more in terms of geology on Day 2, but the picturesque drive was superlative, and I did notice an interesting phenomenon about the Columbia river that tweaked my hydrologic bone...<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgcK4uhIDj0_YeJAY1rv3oktx_eATq82EAyX8JwtOyZUV99eoMoKD9jx4pRzY7Bw2uujeLW_6Odc_2D4BZK-HHYVPLJUe01MIZcnugUdgJC8h2AsXF3KtTBSm_nkX_ea7SN7HkGrA6AQEc/s1600/Picture+078.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="328" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgcK4uhIDj0_YeJAY1rv3oktx_eATq82EAyX8JwtOyZUV99eoMoKD9jx4pRzY7Bw2uujeLW_6Odc_2D4BZK-HHYVPLJUe01MIZcnugUdgJC8h2AsXF3KtTBSm_nkX_ea7SN7HkGrA6AQEc/s640/Picture+078.jpg" width="550" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Looking west on the Columbia River along I84, just outside of Rufus. Those are whitecaps, not rapids</td></tr>
</tbody></table>Winds were gusting up to 70 kph, making it hard to open the car door, but I had to snap a photo of the waves on the Columbia going against the current. That's right, against the current, upstream, eastward. This isn't abnormal or against the laws of physics. All I can see as an observer is the surface of the river, and out of the two forces acting on the surface, the winds are winning...on the surface. Who knows how far down the water depth column the winning force becomes the downstream current? 3, 4, 5 feet, out of hundreds of feet? I couldn't exactly whip out a dingy and a current meter and head out into the frenzied waters, though I wish I could. In any case, interesting food for thought as I travel towards the multitude of high waterfalls that would be the 3rd day of my Columbia Basin trip.<br />
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgmm_ek4UhJmo3Z2lLDw_kI3O2LKqORLkUkW_FMG_4ktu_iV6VsWaf522uRm4kBypRBeaG6ABPDuwbvClTxdfXC6FBi-ohWZYeCx6qSHnv5sTmc7qmQfPjy-QHjkYA-qIj4qG9jxRLlqO8/s1600/twospheres.jpg" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgmm_ek4UhJmo3Z2lLDw_kI3O2LKqORLkUkW_FMG_4ktu_iV6VsWaf522uRm4kBypRBeaG6ABPDuwbvClTxdfXC6FBi-ohWZYeCx6qSHnv5sTmc7qmQfPjy-QHjkYA-qIj4qG9jxRLlqO8/s1600/twospheres.jpg" /></a><br />
<br />
Additional Info:<br />
<ul><li><a href="http://vulcan.wr.usgs.gov/Volcanoes/ColumbiaPlateau/summary_columbia_plateau.html">USGS - Columbia River Flood Basalts</a></li>
<li><a href="http://www.sciencedirect.com.ezproxy.kwantlen.ca:2080/science?_ob=ArticleURL&_udi=B6WPN-4DV0V55-18&_user=1898427&_coverDate=11%2F30%2F1984&_alid=1736139008&_rdoc=10&_fmt=high&_orig=search&_origin=search&_zone=rslt_list_item&_cdi=6995&_st=13&_docanchor=&_ct=28&_acct=C000055247&_version=1&_urlVersion=0&_userid=1898427&md5=9479fe32981cb63921034c22a3d35887&searchtype=a">G. K. C. Clarke et al - Outburst floods from glacial Lake Missoula</a></li>
<li><a href="http://oceanservice.noaa.gov/education/kits/estuaries/media/supp_estuar05a_wedge.html">NOAA - Salt-wedge estuaries</a> </li>
<li><a href="http://www.youtube.com/watch?v=NyIX3SXHyvs">Wind Energy Facilities in the Columbia River Gorge? </a></li>
</ul>Malcolm V Lhttp://www.blogger.com/profile/00126268490488546890noreply@blogger.com0tag:blogger.com,1999:blog-2188731877707108811.post-72426615694188308502011-04-29T15:16:00.000-07:002011-04-29T15:16:41.041-07:00Columbia Basin Trip: Day 1 - a Lahar and an Anticline<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi-C696rJiGNuJPtEffXzXNG5MPfiNjyLuFPFWRn0i_GlVMI8xqR1ZO9jRAVIhakKJVV8piSqiazztb-yeXn2qFN3vaKPSihNPrYRXVXWLyZpMgY11JAbTby9FxmZjoQw0dGewYppZWHQc/s1600/Picture+032.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="338" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi-C696rJiGNuJPtEffXzXNG5MPfiNjyLuFPFWRn0i_GlVMI8xqR1ZO9jRAVIhakKJVV8piSqiazztb-yeXn2qFN3vaKPSihNPrYRXVXWLyZpMgY11JAbTby9FxmZjoQw0dGewYppZWHQc/s640/Picture+032.jpg" width="500" /></a></div>Only now at the end of April do I have a moment to breath, as two tough terms that went by like a blur have come to their inevitable summer conclusion, and the search for work placement begins. But before the hunt begins, a getaway for a few days was what my figurative spirit called for. I'm the outdoors type (is any geoscience type not?), thus I'm allergic to staying indoors when I have some time off. After perusing through <a href="http://www.ellenmorrisbishop.com/">Ellen Morris Bishop's</a> <a href="http://www.amazon.com/Hiking-Oregons-Geology/dp/0898868475">Hiking Oregon's Geology</a> book, I was inspired to try out some of the listed hikes. The trip I took along the Columbia River Gorge was astoundingly beautiful, and the forces of nature were out to make it an interesting few days.<br />
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<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh_LnbuvDaL5wNbaadV_JSMIZs66UqxOZkkv2oT23K7B19MOJJN02FYdsFTgynGaEG7oyVnUF3sU50vUibJdudUHmI4dKh_lu4rDWzA4dlyubLtoL2jNerUKlbB20h7hISecEoay9ENYEk/s1600/Untitled.png" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" height="181" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh_LnbuvDaL5wNbaadV_JSMIZs66UqxOZkkv2oT23K7B19MOJJN02FYdsFTgynGaEG7oyVnUF3sU50vUibJdudUHmI4dKh_lu4rDWzA4dlyubLtoL2jNerUKlbB20h7hISecEoay9ENYEk/s200/Untitled.png" width="200" /></a></div><div style="margin-bottom: 0cm;">After a few hours driving, the first stop was an aside from I90-East, to visit the roadcut that exposes the <a href="http://www.worldcat.org/title/yakima-basalt-and-ellensburg-formation-of-south-central-washington/oclc/3633656">Ellensburg Formation</a> lahars (N 47° 06.041 W 120° 41.705). Driving along the windy stretches of central Washington, this slice of roadside geology was quite the treat. The lahar members of the formation stick out quite noticeably from among the semi-arid grass veneer over basaltic lava flows typical of the <a href="http://en.wikipedia.org/wiki/Columbia_River_Basalt_Group">CRBG</a> region. This lahar exposure, resulting from a muddy mix of water with pyroclastics & ash originating 50km away, is but one example of over a dozen such deposits which have been discovered around <a href="http://en.wikipedia.org/wiki/Kittitas_County,_Washington">Kittitas</a> and <a href="http://en.wikipedia.org/wiki/Yakima_County">Yakima</a> counties.</div><div style="margin-bottom: 0cm;"><br />
</div><div style="margin-bottom: 0cm;">This particular Miocene lahar deposit has some unique features, including an erratic conglomerate boulder that was carried by the great erosive force, and a plethora of broken-up crossbeds. This is typical of the stratigraphy of lahar deposition, which generally includes a bottom layer of eroded country material, followed by the bulk lahar layer composed of grains ranging from silt - boulder size, and finally the top layer of mostly sand with interbedded bits of gravel & pebbles arranged in a disarray of swooping crossbeds, indicative of a highly turbulent current during deposition. When scrutinizing the roadcut, I could feel the sandy texture, and noticed various discontinuous crossbed forms. The granules were mostly hornblende, feldspar, and some distinct pink Ca pyroxene minerals.</div><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgBRJ6T8u_OOt060rm2wZ6P8iLEhd3mX5gk2iZMMsxU0CpwgNB_l-Q3PRkgxrghV6SiZbMasE0Y3lfOOwhhcwm-5R5TdTuWmBNFsUsbnkxG02bwT_xPAndVO-DR0SpxuGNJpL1s7HMIBiM/s1600/Picture+006.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="134" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgBRJ6T8u_OOt060rm2wZ6P8iLEhd3mX5gk2iZMMsxU0CpwgNB_l-Q3PRkgxrghV6SiZbMasE0Y3lfOOwhhcwm-5R5TdTuWmBNFsUsbnkxG02bwT_xPAndVO-DR0SpxuGNJpL1s7HMIBiM/s640/Picture+006.jpg" width="500" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">The generic X-sec of a pumice-laden lahar (left); discontinuous crossbed forms near the base (middle, pen for scale); the roadcut along route 10 showing the poorly sorted Ellensburg Formation lahar mass (right)</td></tr>
</tbody></table><hr /><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgqVFLB8z45oKTZbn-Y8qw0NoeR5o42zREsjMyf_HBpioz3yIfBrX3Fw2LqBfEJ3Uya33wB2wNO35OlAx-jE3HwPNd36FsKxZ7Z7LvgHuR4Unpu_M-LjjjgCDO5dO1p05gTC2erDNBflyY/s1600/Picture+016.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="300" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgqVFLB8z45oKTZbn-Y8qw0NoeR5o42zREsjMyf_HBpioz3yIfBrX3Fw2LqBfEJ3Uya33wB2wNO35OlAx-jE3HwPNd36FsKxZ7Z7LvgHuR4Unpu_M-LjjjgCDO5dO1p05gTC2erDNBflyY/s640/Picture+016.jpg" width="500" /></a></div>Shortly after the stop at the lahar was the first hike on the trip, and it turned out to be one of the best hikes I've had in a long time. This is BBC → Beautiful Basalt Country. A tributary creek of the <a href="http://www.blm.gov/or/resources/recreation/site_info.php?siteid=251">Yakima River canyon</a>, called the <a href="http://www.blm.gov/or/resources/recreation/site_info.php?siteid=265">Umtanum</a>, has a never-ending trail that takes hikers through a varied landscape of exotic vegetation, eclectic creatures, and fantastical basalt shapes. Obviously I focused on the latter, but tried my best to frame shots to include the colorful blooming trees and the out-of-sync redwoods I spotted. The basalt exposures became more plentiful and protruding the further I hiked in, to the point where I could see plenty of examples of entablature, pillow, and columnar basalt all within a small radius. The multiple flood basalt lava flows of the CRBG that effused throughout the Neogene gave the Umtanum creek canyon its layered characteristics, with varied thicknesses and formational conditions combining to define the Yakima Basalts you would see there.<br />
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjtc_6ysGvRmOER-8CNj0OC6K_blgh-_V9P0R2xU6-84qKdZGBWyk7dF4CQMFsCAU31j7lg0E-8LQyx0RkEZeihL3HhtIUd81cyTN-OjfGkk_PAZeVJxVGOIGjhSCWpQvpXsglXODgMjUw/s1600/Picture+027.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="207" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjtc_6ysGvRmOER-8CNj0OC6K_blgh-_V9P0R2xU6-84qKdZGBWyk7dF4CQMFsCAU31j7lg0E-8LQyx0RkEZeihL3HhtIUd81cyTN-OjfGkk_PAZeVJxVGOIGjhSCWpQvpXsglXODgMjUw/s400/Picture+027.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Example of eroded/oxidized remnants of columnar Yakima Basalts </td></tr>
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgRzDroWLQxHgTD9YV60vzbNGueW0KkFm2bblwVpMPu26wSFLQs9AzRzzyWVy81RqRda9inPH34imd0XE5ZVG7YiO49t1Id44_ryzWmtQJRn_wycJm-QbhpAFWejm0KFivlD6aK6DGUMpQ/s1600/Picture+041.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="291" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgRzDroWLQxHgTD9YV60vzbNGueW0KkFm2bblwVpMPu26wSFLQs9AzRzzyWVy81RqRda9inPH34imd0XE5ZVG7YiO49t1Id44_ryzWmtQJRn_wycJm-QbhpAFWejm0KFivlD6aK6DGUMpQ/s400/Picture+041.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Boundaries between lava flows is visible on many faces in the Umtanum creek canyon. The purple line divides the lower columnar basalt from the proceeding pillow basalt above. Some surface expression of flows are hidden behind talus or broken up.</td></tr>
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiM2wZLlcdUeqDk8J0zNaXQr9dvB0kGXe7JouEuua7vH8ihgCQzzmlKzHp0Sv4qIoYWzSKy6yfitWKPQqvEbD_QpQPHHd9bpZKOFDts0vEu1bEm2HQg_95neILDEK0r3d9WSAosDy3fWIU/s1600/Picture+031.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="290" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiM2wZLlcdUeqDk8J0zNaXQr9dvB0kGXe7JouEuua7vH8ihgCQzzmlKzHp0Sv4qIoYWzSKy6yfitWKPQqvEbD_QpQPHHd9bpZKOFDts0vEu1bEm2HQg_95neILDEK0r3d9WSAosDy3fWIU/s400/Picture+031.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Columnar, Hackly, Pillow, all visible on one face</td></tr>
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<hr />On my way out, a last pullover harkened to me, maybe because my GPSr kept bleeping at me that an <a href="http://www.geocaching.com/seek/cache_details.aspx?guid=e90030f1-c973-47ae-a4c1-0dbf76e1940d">earthcache</a> was nearby. Lo and behold a small monument to plate tectonics + fluvial processes in geomorphology. What did it say? To frame it geologically: The Yakima Basalts and Ellensburg Formation lava flows are quite thick, on the order of a few kilometers, and fluvial downcutting into them still has a ways to go (core drilling down 3 km's still hadn't reached a different basement lithology). On top of that thickness, folding into anticlines & synclines occurred due to north-south trending compression. One particular anticline, the Umtanum ridge anticline, is noticeable if you have a good eye for the big picture. It stretches for over 80km, and with such a large scale and broad sweep it might be hard to notice the bend that defines the anticline. <br />
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEirAdeaCsy-1QplHQfyE7pUB27lzwqrgyogD8vp9r6vFUnq0B8UQstseTzy_Pn2Keord0zHwobvr-DAlFK8ck-fsdW3jtZJp9dfDAIhotlhOZsXV_NmyJzMpHbpvz5fA35kuWVlEvfSZDs/s1600/Picture+047.jpg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="250" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEirAdeaCsy-1QplHQfyE7pUB27lzwqrgyogD8vp9r6vFUnq0B8UQstseTzy_Pn2Keord0zHwobvr-DAlFK8ck-fsdW3jtZJp9dfDAIhotlhOZsXV_NmyJzMpHbpvz5fA35kuWVlEvfSZDs/s400/Picture+047.jpg" width="246" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Evolution of Yakima river course during folding</td></tr>
</tbody></table></div><br />
Due to the slow warping matching the slow downcutting of the Yakima river, the river has cut its course through the basaltic layers and created a water gap. The river retained most of its sinuosity whilst doing so, spending its erosive force cutting through the basalt rather than cutting a straighter channel as the gradient increased. Another great earthcache with lots of information and excellent diagrams provided by local organizations, in this case the <a href="http://www.parks.wa.gov/">Washington State Parks and Recreation Commission</a>.<br />
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There were other interesting stops along the routes and highways, where roadcuts exposed features and structures that demanded scrutiny. I saw no less than several examples of tilting, faulting, and various forms of basalt in numerous shapes that would make cumulus clouds envious. The vegetation of the <a href="http://en.wikipedia.org/wiki/Columbia_Plateau_%28ecoregion%29#Umatilla_Plateau_.2810c.29">Umatilla Plateau</a> & <a href="http://en.wikipedia.org/wiki/Columbia_Plateau_%28ecoregion%29#Yakima_Folds_.2810g.29">Yakima Folds</a> ecoregions gave a splash of variety & color in springtime that is quite unique and unparalleled. The next day took me into new and interesting places, more CRBG but in different flavors. Day 2 post to follow...<br />
<div class="separator" style="clear: both; text-align: center;"></div></div><div style="margin-bottom: 0cm;"><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEif5T7qlPfyIck6A1u3VRRrKVd1DlBj2t4js6yHiXxShIPNC0xxt-xV1WbgAU-0hxwdAOWLMGjaMDyrQwA3OAa3K6GN_lFMr069zFd3Gmc_DmQ3pjszt63oBgcOlUazB5RvWFgGz4Fjyhw/s1600/Picture+058.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="262" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEif5T7qlPfyIck6A1u3VRRrKVd1DlBj2t4js6yHiXxShIPNC0xxt-xV1WbgAU-0hxwdAOWLMGjaMDyrQwA3OAa3K6GN_lFMr069zFd3Gmc_DmQ3pjszt63oBgcOlUazB5RvWFgGz4Fjyhw/s640/Picture+058.jpg" width="550" /></a></div><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgmm_ek4UhJmo3Z2lLDw_kI3O2LKqORLkUkW_FMG_4ktu_iV6VsWaf522uRm4kBypRBeaG6ABPDuwbvClTxdfXC6FBi-ohWZYeCx6qSHnv5sTmc7qmQfPjy-QHjkYA-qIj4qG9jxRLlqO8/s1600/twospheres.jpg" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgmm_ek4UhJmo3Z2lLDw_kI3O2LKqORLkUkW_FMG_4ktu_iV6VsWaf522uRm4kBypRBeaG6ABPDuwbvClTxdfXC6FBi-ohWZYeCx6qSHnv5sTmc7qmQfPjy-QHjkYA-qIj4qG9jxRLlqO8/s1600/twospheres.jpg" /></a>Additional Info:<br />
<ul><li><a href="http://geonames.usgs.gov/pls/gnispublic/f?p=gnispq:3:1224541714697098::NO::P3_FID:1527596">USGS Coordinate Info for Umtanum Ridge features</a></li>
<li><a href="http://www.amazon.com/Glacial-Lake-Missoula-Humongous-Floods/dp/0878424156/ref=sr_1_1?ie=UTF8&s=books&qid=1304109467&sr=8-1"><span class="citation book">David Alt - </span>Glacial Lake Missoula and Its Humongous Floods</a></li>
<li><a href="http://www.amazon.com/Continental-Basalts-Petrology-Structural-Geology/dp/9027728062/ref=sr_1_2?s=books&ie=UTF8&qid=1304109584&sr=1-2">J. D. MacDougall - Continental Flood Basalts (Petrology and Structural Geology)</a></li>
<li><a href="http://books.google.ca/books?id=F1Sx3i2CZyUC&pg=PA203&lpg=PA203&dq=ellensburg+lahar&source=bl&ots=BVZckuQUaj&sig=erFKjHiqdi-GQUGCk1ZqgBluLBw&hl=en&ei=lyK7Tba_MZTGsAPz_qXZBQ&sa=X&oi=book_result&ct=result&resnum=8&ved=0CFQQ6AEwBw#v=onepage&q=ellensburg%20lahar&f=false">Floods, Faults, and Fire: Geological Field Trips in Washington State</a> </li>
</ul></div>Malcolm V Lhttp://www.blogger.com/profile/00126268490488546890noreply@blogger.com0tag:blogger.com,1999:blog-2188731877707108811.post-85471307284156593252011-04-17T17:30:00.000-07:002011-04-17T17:30:14.461-07:00Learning from the gentry: Maars and Tuff RingsUni classes that specialize in intermediate - advanced volcanism are few & far between in my neck of the woods. Prior to the 4th year courses that dive into rheological properties of magmas and lavas, detailed structures of volcanic landforms, eruption dynamics, and mechanics of volcaniclastic deposition (at least according to the <a href="http://www.sfu.ca/earth-sciences/courses/ugrad/outlines/421.html">course outline</a>), us undergrads get treated to repetitions of the usual volcanology basics as it pertains to other geoscience disciplines. It gets a bit tiresome going over the <a href="http://en.wikipedia.org/wiki/Volcanic_Explosivity_Index">VEI</a> for the umpteenth time, and retreads about the same types of volcanoes erupting the same types of lava. Variations within a single volcano don't exist before 4th year, and probing questions are usually met with the full-stop response "But for <b>this course</b> you only need to know...".<br />
<br />
<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhbOmWD2c-MShYyZyE5dpPTO4v_ga5nqO4wXjkyqW87niaYv5Pzo0Jb4Xdf6pkgoAdEVQLtuaCtR6_le-9Ak-z1cLvLcd8-kFTXkDRljoGFiFPP0VVhHo5d2x2GeDNN5tBCDOPTtn-2buk/s1600/Untitled.png" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="200" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhbOmWD2c-MShYyZyE5dpPTO4v_ga5nqO4wXjkyqW87niaYv5Pzo0Jb4Xdf6pkgoAdEVQLtuaCtR6_le-9Ak-z1cLvLcd8-kFTXkDRljoGFiFPP0VVhHo5d2x2GeDNN5tBCDOPTtn-2buk/s200/Untitled.png" width="196" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Diagram of the various zones and<br />
facies of a maar-diatreme</td></tr>
</tbody></table>So I've had to teach myself some ins and outs of volcanism to go beyond the basics. The <a href="http://www.amazon.com/Volcanoes-Firefly-Guide-Mauro-Rosi/dp/1552976831">Firefly guide</a> was a good start, and had more in-depth technical detail than I expected. After looking at some sites in the High Lava Plains of Oregon, I became familiar with features called maars and tuff rings. Courtesy of <a href="http://blogs.agu.org/magmacumlaude/">Jessica Ball</a>, I was pointed in the direction of certain papers written by Volker Lorenz, most notably on "Maar-Diatreme Volcanoes, their Formation, and their Setting in Hard-rock or Soft-rock Environments". It's an excellent read, and lays out the details of these structures as seen in varying locations, plus methods of emplacement during different periods of volcanism. Magma's interaction with various types of aquifers, and how each can produce a different maar-diatreme cross-section is also outlined.<br />
<br />
The features themselves might lean towards the esoteric, but when trying to find places of interest that can offer something new to digest whilst hiking around, maars and tuff rings fit right in with <a href="http://en.wikipedia.org/wiki/Tuya">tuya's</a>, obsidian flows, lava domes, and other under-appreciated volcanic gems of the landscape. Some of the interesting, more explicit facts I discerned from Lorenz's paper include:<br />
<ul><li>Vast majority of maar-diatreme volcanic features occur in silica-poor (basaltic) volcanic fields </li>
<li>Tuff Rings/Cones are thought of as the phreatomagmatic equivalent of rhyodacitic lava domes</li>
<li>Posteruption, diatremes develop unique stratification of different facies (tuff, volcaniclastics, breccias, sediments, xenoliths)</li>
<li>Maar lakes are generally short lived, as sediment fills in the shallow depression. If one exists, it indicates a geologically recent phreatomagmatic eruption</li>
<li>The greater the volume of the Tuff Ring formed, the smaller the volume of lahars produced in the same phreatomagmatic eruption (subtraction of tuffaceous material from potential flow)</li>
<li>Maars created within a jointed aquifer (hard rock that is heavily faulted) result in posteruptive diatreme pipes that are among the widest, due to block collapse of the hard rock edifice</li>
<li>The center of Maars and Tuff Rings can have a measurable gravity anomaly when compared to the surrounding country rock</li>
<li>The inclusion of irregularly distributed groundwater in the rising magma of an eruption can change the viscosity of the magma, and thus result in irregular eruptions and tephra deposition</li>
<li><a href="http://en.wikipedia.org/wiki/Diagenesis">Diagenesis</a> (a water-driven metamorphosis of sediments) is frequent in diatremes of kimberlite pipe origin near mid-ocean ridges, ie. olivine can hydrate into serpentine and thus shrink the diatreme pipe diameter</li>
</ul>Those points are my interpretation, and I might be off (at least until year 4). The only experience I have with maars and tuff rings is from a trip into south-central <a href="http://en.wikipedia.org/wiki/Lake_County,_Oregon">Oregon's Lake county</a>. Unfortunately, it was several years ago, prior to my budding interest in the geosciences. However, <a href="http://en.wikipedia.org/wiki/Fort_Rock">Fort Rock</a> and <a href="http://en.wikipedia.org/wiki/Hole-in-the-Ground">Hole-in-the-Ground</a> are excellent stops for marvelling at a standout tuff ring and maar not 10km from each other. They are part of a basin of primarily Quaternary alluvium eroded & transported from the High Lava Plains province/Steen's basalt group. During their diatreme eruptions in the Pleistocene, they were inland lakes, hence their genesis.<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjhFnV8RFU9Wi8eAuz-RshHggDh3xLmsFAiTz5Gzndc8cbA8_oWFHpsqFW52n7kpUDN-HBtYoyNeofrnnP8HDQKez1XtRwKVGQRLtcX2jM0mmdnVrBH4JNWn9t6y27asxrLFxFpzmDkIpc/s1600/3747409833_c8041e81fc_z.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="200" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjhFnV8RFU9Wi8eAuz-RshHggDh3xLmsFAiTz5Gzndc8cbA8_oWFHpsqFW52n7kpUDN-HBtYoyNeofrnnP8HDQKez1XtRwKVGQRLtcX2jM0mmdnVrBH4JNWn9t6y27asxrLFxFpzmDkIpc/s640/3747409833_c8041e81fc_z.jpg" width="550" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Hole-in-the-Ground maar (left) and Fort Rock tuff ring (right), both protected as Oregon state parks<br />
43° 23.314'N 121° 7.919'W will place you smack between the two</td></tr>
</tbody></table><br />
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjloSOn-6xuJ6D2cillA1G6D9a9FY0iTHqY9fO48AikcLsSDoymkbddzXR2o-QS6qRII7bAp7g31XJWaheeH_nIC4LU4Zyqs4nucoNMoizS-slCvizM617gY_8x5q555PHmC9MkV_D-Ymk/s1600/litho.jpg" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjloSOn-6xuJ6D2cillA1G6D9a9FY0iTHqY9fO48AikcLsSDoymkbddzXR2o-QS6qRII7bAp7g31XJWaheeH_nIC4LU4Zyqs4nucoNMoizS-slCvizM617gY_8x5q555PHmC9MkV_D-Ymk/s1600/litho.jpg" /></a>Additional Info:<br />
<ul><li><a href="http://geolines.gli.cas.cz/fileadmin/volumes/volume15/G15-072.pdf">Volker Lorenz - Maar-Diatreme Volcanoes, their Formation, and their Setting in Hard-rock or Soft-rock Environments </a></li>
<li><a href="http://www.mantleplumes.org/HighLavaPlains.html">Brennan T. Jordan - The Oregon High Lava Plains: Proof against a plume origin for Yellowstone?</a></li>
<li><a href="http://vulcan.wr.usgs.gov/Glossary/Maars/framework.html">USGS - Maars and Tuff Cones</a></li>
<li><a href="http://www.sciencedirect.com.ezproxy.kwantlen.ca:2080/science?_ob=ArticleURL&_udi=B6VCS-5259C4P-1&_user=1898427&_coverDate=04%2F15%2F2011&_alid=1721464011&_rdoc=5&_fmt=high&_orig=search&_origin=search&_zone=rslt_list_item&_cdi=5962&_sort=r&_st=13&_docanchor=&view=c&_ct=215&_acct=C000055247&_version=1&_urlVersion=0&_userid=1898427&md5=972c0e3c585268a921793b0c6137763f&searchtype=a">J.D.L. White - Maar-diatreme volcanoes: A review</a><br />
</li>
</ul>Malcolm V Lhttp://www.blogger.com/profile/00126268490488546890noreply@blogger.com1tag:blogger.com,1999:blog-2188731877707108811.post-62960184161553549942011-04-08T22:17:00.000-07:002011-04-08T22:17:02.025-07:00The Chief of a thousand<div style="margin-bottom: 0cm;">The 1000<sup>th</sup> geocache is a milestone that calls for a significant effort to find a spectacular cache. I've never been up the <a href="http://en.wikipedia.org/wiki/Stawamus_Chief">Stawamus Chief's</a> backside, and only once have I been up the sheer face when my rock climbing friend hauled my frightened self up that hard way. So up the back of the Chief it was decided, and one of the caches placed on the three peaks would do nicely as the milestone.</div><div style="margin-bottom: 0cm;"><br />
</div><div style="margin-bottom: 0cm;">On Thursday I had an opening, during a lull in work/schoolwork, to finally get back to nature after 3 months of being sequestered from the intense parts of it. I'd not recommend doing the Chief hike as your first hike in a long while; my thighs are burning and my joints crackling after the 3km→ 600m↑. But I did enjoy myself immensely. The weather was perfectly clear, mild, and the trail had recent maintenance. It wasn't busy but it wasn't abandoned, and one bloke I had a chat with on the first peak was an expat from Darwin who is going to UBC to pursue a postgraduate in materials science (he mentioned to me a <a href="http://en.wikipedia.org/wiki/Mount_conner">Mount Conner</a> not far from <a href="http://en.wikipedia.org/wiki/Uluru">Uluru</a>). The caches themselves were easy to find, as the GPSr was on target all day long.</div><div style="margin-bottom: 0cm;"></div><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhuppc1FRpOkTwaP51_hXkys757gQyBoR0u0lRigH4ScJMnoOPaQKSe2uHMxUoK3RQi3Jbdnb85AS6yCkJYMJ8EfQaPSVxvSE1iKALvEeyASQyQ0CwdBoT6A797GIo693FCCRaPlmHChmw/s1600/chiefgeo.jpg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="228" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhuppc1FRpOkTwaP51_hXkys757gQyBoR0u0lRigH4ScJMnoOPaQKSe2uHMxUoK3RQi3Jbdnb85AS6yCkJYMJ8EfQaPSVxvSE1iKALvEeyASQyQ0CwdBoT6A797GIo693FCCRaPlmHChmw/s320/chiefgeo.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">BC Parks info board explaining the Chief's physical geology</td></tr>
</tbody></table><div style="margin-bottom: 0cm;"><br />
</div><div style="margin-bottom: 0cm;"></div><div style="margin-bottom: 0cm;">Going up such an icon of granite switches my eyes & mind into a geology mode. Up the trail there is little to see besides heavy vegetation and rock rubble. From pieces of the rubble, I spotted some mica schist, granulite, syenite, conglomerate of generally small grains, and of course granodiorite grading to granite or grading to diorite. Indeed a hodgepodge of igneous potatoes with a bit of high energy sedimentary gravy thrown in. One particular opening to the side of the trail halfway up was the home of an oddly placed erratic, which upon investigation appeared to be a 3 meter diameter colluvial boulder of the same lithology as the country rock.</div><div style="margin-bottom: 0cm;"><br />
</div>This opening was also the first place to showcase the dominant process that is the hidden danger of the Chief trails → <a href="http://en.wikipedia.org/wiki/Exfoliation_%28geology%29">exfoliation</a>. On the farside mountain rockface I could see indication of rockfalls via detachment, and further up the trail there was a couple extreme overhanging weathered blocks that I've termed "jenga granite" (see picture below). Glacial activity during the Pleistocene exploited cracks & joints formed via uplift and exfoliation of the granite family rocks making up the massif. Once the trail started heading straight up the ladders & chains, the general hiking boots were swapped for the rock scrambling shoes, and the surface of the true Chief was exposed to the heavens. The Chief is not exactly geologically spectacular along the top, as what you'll see is mostly weather-beaten granodiorite with splotches of diorite & granulite xenoliths up to beachball sizes. The real treat is the views of <a href="http://en.wikipedia.org/wiki/Howe_sound">Howe Sound</a>, the ant-colony of <a href="http://en.wikipedia.org/wiki/Squamish,_British_Columbia">Squamish</a>, and the snowbound <a href="http://en.wikipedia.org/wiki/Mount_Garibaldi">Mount Garibaldi complex</a>. The icing on the cake was not dying on the way down the steep center peak, and not sustaining any injuries after an absence from strenuous hiking. Heading into town afterwards for some goods & services was a perfect time to marvel at the sheer granite rockface that looms over Squamish. A keen eye will spot the darker 'slash' that turned Stawamus Chief from a monolith into a bilith 30 Ma ago. <br />
<div style="margin-bottom: 0cm;"><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhFEjPiTuElkDe0fK4R2D3ewnRbsGKFxs7C-ZRNbFzC2VLgpwd5rFB5EZRmYfr91uKiey9V8qubDwc3Km2FMm2BBpmxiPTO5imVqV38u1duTEFJeAUQILl-t51YFPSzF0PGHgp79RbbRwU/s1600/rfacedetachment.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="202" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhFEjPiTuElkDe0fK4R2D3ewnRbsGKFxs7C-ZRNbFzC2VLgpwd5rFB5EZRmYfr91uKiey9V8qubDwc3Km2FMm2BBpmxiPTO5imVqV38u1duTEFJeAUQILl-t51YFPSzF0PGHgp79RbbRwU/s400/rfacedetachment.jpg" width="530" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Examples of exfoliation along Chief trail. Slab detachment on the left, jenga-like sheet fractures on the right</td></tr>
</tbody></table>Now that I've hit 1000 I'm a veteran of the hobby, and over the two years I've hunted for those little plastic containers, I've developed some likes and dislikes about it. Thus my forthgoing geocaching focus will lean towards earthcaches plus interesting backwoods/backcountry hikes, and not bothering so much with urban micros and tourist traps.<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjmPF31xHDy9D1yypKOg5ZHi-mYBTkOLqxs3gbxBiQq8B2OP2VNq_t3mJkgmX9jlucoSpUuZERdJKpTasMdHsJIbEZYoSCKQBxPgwdD86yyu4kRMoHaMCaHjhyphenhyphen5vClPZ9zINaEpiruvLz0/s1600/garibaldi.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="296" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjmPF31xHDy9D1yypKOg5ZHi-mYBTkOLqxs3gbxBiQq8B2OP2VNq_t3mJkgmX9jlucoSpUuZERdJKpTasMdHsJIbEZYoSCKQBxPgwdD86yyu4kRMoHaMCaHjhyphenhyphen5vClPZ9zINaEpiruvLz0/s640/garibaldi.jpg" width="530" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Why is it every time I see this mountain I think of Babylon 5?</td></tr>
</tbody></table></div><div style="margin-bottom: 0cm;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjloSOn-6xuJ6D2cillA1G6D9a9FY0iTHqY9fO48AikcLsSDoymkbddzXR2o-QS6qRII7bAp7g31XJWaheeH_nIC4LU4Zyqs4nucoNMoizS-slCvizM617gY_8x5q555PHmC9MkV_D-Ymk/s1600/litho.jpg" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjloSOn-6xuJ6D2cillA1G6D9a9FY0iTHqY9fO48AikcLsSDoymkbddzXR2o-QS6qRII7bAp7g31XJWaheeH_nIC4LU4Zyqs4nucoNMoizS-slCvizM617gY_8x5q555PHmC9MkV_D-Ymk/s1600/litho.jpg" /></a>Additional Info:</div><ul><li><a href="http://www.env.gov.bc.ca/bcparks/explore/parkpgs/stawamus/">Stawamus Chief Provincial Park</a></li>
<li><a href="http://www.geocaching.com/seek/cache_details.aspx?guid=23ab4115-cae1-47c0-bd8c-bd2fd5b00294">Peaked out! Stawamus Chief geocache</a></li>
<li><a href="http://gsc.nrcan.gc.ca/urbgeo/vanrock/chief_e.php">The Chief: Pillar of Granite</a></li>
</ul>Malcolm V Lhttp://www.blogger.com/profile/00126268490488546890noreply@blogger.com1tag:blogger.com,1999:blog-2188731877707108811.post-54182602854402459372011-03-29T11:29:00.000-07:002011-03-29T11:29:45.521-07:00Field photo Set #2Late March - early April is the end of semester period, thus I'm swamped with term papers, labs, and presentations. I'm not one to procrastinate, since I've been burned by it in the past and learned my lesson. But activities like blogging must take a back seat, and I'm sure most reading this blog are experienced in what the last month of a semester is like.<br />
<br />
So to keep things simple, for me and for you, but mostly for me, I have another pair of field photos to show, replete with explanation for the features' what/when/where/how. This time, a pair of volcanically-derived features in Oregon, both derived from eruptive activity from the legendary <a href="http://en.wikipedia.org/wiki/Mount_Mazama">Mt. Mazama</a> complex in what is today <a href="http://www.nps.gov/crla/index.htm">Crater Lake National Park</a>.<br />
<br />
<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh2aFypbLqAEpNn6ky-97UsjdNqpr0hzexWQPutw7TP-V5Mj3-HcoDFmUJB5EJKLZlBwepRba-jwkAKSbAm8z9k-91Mgk5wbcjBeNj22NCTNg4orPYgzcrszYs5W6Zj3LmfK4qjlzSa9Oo/s1600/weldedfumarole.jpg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh2aFypbLqAEpNn6ky-97UsjdNqpr0hzexWQPutw7TP-V5Mj3-HcoDFmUJB5EJKLZlBwepRba-jwkAKSbAm8z9k-91Mgk5wbcjBeNj22NCTNg4orPYgzcrszYs5W6Zj3LmfK4qjlzSa9Oo/s320/weldedfumarole.jpg" width="267" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">The Pinnacles fumarole features, looking west.<br />
The V-shape valley shows river erosion exposing them</td></tr>
</tbody></table>To the right is a snapshot of the elegant Pinnacles, located just a couple of kilometers to the east of Crater Lake. These spires were ancient fumarole conduits of Mazama's gaseous content (SO<sub>2</sub>, CO<sub>2</sub>, H<sub>2</sub>S), exposed by fluvial erosion from a radial stream, but remaining resistant to that erosive force. Prior to the finale of Mazama's VEI 7 eruption 7.7 Ka ago, a <a href="http://library.thinkquest.org/17457/volcanoes/hazards.nuee.php">nuée ardente</a> flowed down Mazama's east flank, carrying <a href="http://en.wikipedia.org/wiki/Scoria">scoria</a>. Gasses escaped from the settling scoria through fumarole vents, and the mineral content, given the extreme heat, welded loose pumice to the sides of the fumaroles. Thus the pinnacles seen to the right are hollow, and are resistant to erosion from the inside-out, which is atypical of common geologic thought.<br />
<br />
When viewing the pinnacles along the 2-3 km path (42° 51.056'N 122° 0.558'W), I noticed that some of the spires had puncture holes in them, in which I could see through. The keen eye will also notice that the base the pinnacles stand on is a lighter color, which is due to the more silica-rich <a href="http://en.wikipedia.org/wiki/Rhyodacite">rhyodacite</a> ash falls that preceeded the scoria-laden pyroclastic flow.<br />
<hr /><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjghwwXbvzh3mxKlB0h8ZmNg6pN_8WcNugQfXWtdK3hwLpdezi_95hyphenhyphensu4xFXWOp5bg_BjCWiB26dSII2zEOnG-IflBELHigsGvYjEXM01fiDRGsS6iRUgH2N4w9pPaVEp9vDxatOAoRrU/s1600/umpquaandyash.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="271" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjghwwXbvzh3mxKlB0h8ZmNg6pN_8WcNugQfXWtdK3hwLpdezi_95hyphenhyphensu4xFXWOp5bg_BjCWiB26dSII2zEOnG-IflBELHigsGvYjEXM01fiDRGsS6iRUgH2N4w9pPaVEp9vDxatOAoRrU/s400/umpquaandyash.jpg" width="400" /></a></div>This field photo is of a roadcut along the North Umpqua highway, not far from <a href="http://en.wikipedia.org/wiki/Watson_Falls">Watson Falls</a> (43° 14.553'N 122° 21.486'W). Catching this roadcut out of the corner of my eye made me glad my car has a low center of gravity. This hillface, ~35km from Crater Lake, showcases silica-rich ashfall from Mazama during its major eruptive phase 7.7 Ka ago. The several-meters thick deposit is a testament to the volume of tephra ejected by the monster eruption (~60 km<sup>3</sup>), and its coverage across the northwest is found much further afield as well (Mount Baker slopes have a few cm thick of Mazama ash deposit, and it's over 600km from Crater Lake). <a href="http://en.wikipedia.org/wiki/Tephrochronology">Tephrochronology</a> analyzes in the region are easily guided by Mazama ash, as the distribution of the ash from the centroid is quite ideal, making it a prime stratigraphic marker for 7.7 Ka.<br />
<br />
The white color stems from <a href="http://en.wikipedia.org/wiki/Sanidine">sanidine</a> feldspar content within the silica-rich ash, and darker grey portions contain a greater percentage of ferromagnesian minerals. The grainsize is quite fine, looks & feels almost silty, with a gritty abrasiveness, but not too harsh and not as hard as sheer-faced plutonic rocks. You can jab this rockface and it feels somewhat padded.<br />
<br />
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjloSOn-6xuJ6D2cillA1G6D9a9FY0iTHqY9fO48AikcLsSDoymkbddzXR2o-QS6qRII7bAp7g31XJWaheeH_nIC4LU4Zyqs4nucoNMoizS-slCvizM617gY_8x5q555PHmC9MkV_D-Ymk/s1600/litho.jpg" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjloSOn-6xuJ6D2cillA1G6D9a9FY0iTHqY9fO48AikcLsSDoymkbddzXR2o-QS6qRII7bAp7g31XJWaheeH_nIC4LU4Zyqs4nucoNMoizS-slCvizM617gY_8x5q555PHmC9MkV_D-Ymk/s1600/litho.jpg" /></a>Additional Info:<br />
<ul><li><a href="http://pubs.usgs.gov/fs/2002/fs092-02/">Mount Mazama and Crater Lake: Growth and Destruction of a Cascade Volcano</a></li>
<li><a href="http://vulcan.wr.usgs.gov/Volcanoes/CraterLake/MazamaAsh/framework.html">Cascades Volcano Observatory - Mazama Ash</a></li>
<li><a href="http://www.amazon.ca/Hiking-Oregons-Geology-2nd-A01/dp/0898868475">Ellen Morris Bishop - Hiking Oregon's Geology</a></li>
<li><a href="http://www.sciencedirect.com.ezproxy.kwantlen.ca:2080/science?_ob=ArticleURL&_udi=B6VCS-489YNWN-18&_user=1898427&_coverDate=10%2F31%2F1983&_alid=1698287089&_rdoc=4&_fmt=high&_orig=search&_origin=search&_zone=rslt_list_item&_cdi=5962&_sort=r&_st=13&_docanchor=&view=c&_ct=856&_acct=C000055247&_version=1&_urlVersion=0&_userid=1898427&md5=654be63caf5368ce0c7d692ef4b87f4a&searchtype=a">Journal of Volcanology and Geothermal Research - Eruptive history of Mount <span class="hit">Mazama</span> and Crater Lake Caldera, Cascade Range, U.S.A.</a></li>
<li><a href="http://www.sciencedirect.com.ezproxy.kwantlen.ca:2080/science?_ob=ArticleURL&_udi=B6V66-4VJ0C4W-5&_user=1898427&_coverDate=05%2F15%2F2009&_alid=1698287089&_rdoc=5&_fmt=high&_orig=search&_origin=search&_zone=rslt_list_item&_cdi=5806&_sort=r&_st=13&_docanchor=&view=c&_ct=856&_acct=C000055247&_version=1&_urlVersion=0&_userid=1898427&md5=3046b7a421796db79c027aedd46d834f&searchtype=a">Charles Mandeville et al - Stable isotope and petrologic evidence for open-system degassing during the climactic and pre-climactic eruptions of Mt. Mazama, Crater Lake, Oregon</a></li>
</ul>Malcolm V Lhttp://www.blogger.com/profile/00126268490488546890noreply@blogger.com0tag:blogger.com,1999:blog-2188731877707108811.post-71726311421664629452011-03-24T23:27:00.002-07:002011-03-28T11:12:37.078-07:00A glance at Saskatchewan Potash mining<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiBeQoRnXGDXBQkSP4VPDSQvGWa8TACCx2TzjBfwS6mqWAOVReGVpWS6PJbH-BOYTrKt3JQo1m5pdcZy3eN73B-BtqxRUbIWSYT1XpreB_y3F1n_a1gPRk1qEZixOo1Q4xngSoO9DcIECk/s1600/agr1490c_158_potash.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="222" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiBeQoRnXGDXBQkSP4VPDSQvGWa8TACCx2TzjBfwS6mqWAOVReGVpWS6PJbH-BOYTrKt3JQo1m5pdcZy3eN73B-BtqxRUbIWSYT1XpreB_y3F1n_a1gPRk1qEZixOo1Q4xngSoO9DcIECk/s400/agr1490c_158_potash.jpg" width="400" /></a></div>Saskatchewan might not at first seem like a province that can build itself up as a preeminent world-class supplier of any resource. The population is only 1 million, spread out over a large area, and the climate has inhospitable extremes in the summer and winter. Yet Saskatchewan has built itself up as a leading supplier of a rare-earth salt called potash. Potash is essentially a water-soluble potassium-rich mineral that is often combined with chloride or carbonate, and it has coalesced in abundance underneath the sedimentary platform that defines the geology of Saskatchewan's prairie-lands. The industrial heart of the province has utilized this abundance to strike at rich in a world market where potash is an excellent & cost effective fertilizer for crops, and markets in India, China and Brazil have made it lucrative for the monopoly that Potash Corp. has created. <br />
<br />
<div style="margin-bottom: 0cm;"><span style="font-size: large;">Why is Saskatchewan so rich in potash? </span></div><div style="margin-bottom: 0cm;"><br />
</div><div style="margin-bottom: 0cm;">That question can be answered by looking at the historical geology of the province. During the Devonian period 390 million years ago, southern Saskatchewan was inundated by a <a href="http://en.wikipedia.org/wiki/Elk_Point_Group">restricted inland sea</a>. The equator was also located close to the province, thus the conditions were ripe for evaporation of water in the ancient sea, and thus the leftover mineral content collected and formed what are called <a href="http://en.wikipedia.org/wiki/Evaporite#Marine_evaporites">evaporite beds</a>. These beds were subsequently covered by later horizontal sedimentary deposits. The capping layers were not too thick, on the order of a thousand meters, thus drilling and mining access to the potash using modern techniques is cost & technically feasible.<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgYQj2qno_GfHfyDao7p9XGHdAxxW9VcD8SLs2_H84KIHPp4zIyjmqGQ_hVAhoDizuKaem4BDHMdakjyTMaTnTs5ZwiUE8U2ymqvBXWDYeKspJvaR-vUjXmf1u2dY8DjM86mY0pqSsf8xg/s1600/Kola_geology.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="185" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgYQj2qno_GfHfyDao7p9XGHdAxxW9VcD8SLs2_H84KIHPp4zIyjmqGQ_hVAhoDizuKaem4BDHMdakjyTMaTnTs5ZwiUE8U2ymqvBXWDYeKspJvaR-vUjXmf1u2dY8DjM86mY0pqSsf8xg/s400/Kola_geology.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">World potash reserves, top ten states (left); cross-section of Saskatchewan strata with sylvinite beds (right)</td></tr>
</tbody></table><span style="font-size: large;">Types and uses of Potash</span><br />
<div style="margin-bottom: 0cm;"><br />
</div><div style="margin-bottom: 0cm;">Potash occurs when Potassium binds with another compound or element to produce a salt. Such compounds include Potassium Chloride (KCl), Potassium Sulphate (K<sub>2</sub>SO<sub>4</sub>), Potassium Carbonate (K<sub>2</sub>CO<sub>3</sub>), and Potassium nitrate (KNO<sub>3</sub>), all of which have varying uses and grades of quality. Potash has general uses as a bleaching agent, a soap, and a de-icer, and technological uses in computer screens, but the majority industrial use of the compound is as a fertilizer of plant crops. The variations of potash mentioned above are all effective as fertilizers, because plants soak up the nutrients provided by potash when they are dispersed and allowed to percolate into the soil (after being soaked by irrigation). Potash's water-solubility allows this to occur effortlessly, and thus crops will soak up the nutrient content as they soak up water.</div><div style="margin-bottom: 0cm;"><br />
</div><div style="margin-bottom: 0cm;">Not many countries produce and export commercial-grade potash, and Canada is by far #1 among the ones that do. Importers tend to be heavily populated countries that rely on extensive agriculture to feed their people.<br />
<br />
<span style="font-size: large;"><a href="http://pumicecastle.blogspot.com/p/glance-at-saskatchewan-potash-mining.html">Click to read more... </a></span></div><div style="margin-bottom: 0cm;"></div></div>Malcolm V Lhttp://www.blogger.com/profile/00126268490488546890noreply@blogger.com4tag:blogger.com,1999:blog-2188731877707108811.post-70961978035841989752011-03-19T13:24:00.000-07:002011-03-19T13:24:01.499-07:00Earth Story: The Beeb's forgotten geology gem<span style="font-family: inherit;">I love it when I'm made aware of a documentary or TV miniseries about geology that I hadn't known existed, and I was just recently introduced to the BBC series called "<a href="http://www.bbcshop.com/science+nature/earth-story-dvd/invt/bbcdvd1988/">Earth Story</a>", an 8-parter released in the late 90's.</span> A professor showed it in my historical geology class, using an old VHS tape of the program from the university archives. He used it to bring attention to such features as <a href="http://pumicecastle.blogspot.com/2011/02/learning-from-gentry-banded-iron.html">Banded Iron Formations</a> and <a href="http://en.wikipedia.org/wiki/Stromatolite">Stromatolites</a>, and such events as the <a href="http://en.wikipedia.org/wiki/Snowball_Earth">Rodinian Snowball Earth</a> and <a href="http://en.wikipedia.org/wiki/ELE">ELE's</a>. It's a perfect fit for a class on the evolution of the planet, and certain episodes would fit well in structural geology, geomorphology, paleontology, and geophysics classes, among others.<br />
<br />
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhAy4p77RP-_y2kfhlzj3YAx5-LA8iw-RuBR3JudGuwFaUFSnvAq3Mb7FmfeQirPSO0kocBle0dyLtuLYV2mDqpFrikcjrANAgj0BHn03Jm1RCBAv7twZSUjnf9YW2tzcDivQ5-j55lkxA/s1600/earth-story_2d_cmyklrg.gif" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" height="190" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhAy4p77RP-_y2kfhlzj3YAx5-LA8iw-RuBR3JudGuwFaUFSnvAq3Mb7FmfeQirPSO0kocBle0dyLtuLYV2mDqpFrikcjrANAgj0BHn03Jm1RCBAv7twZSUjnf9YW2tzcDivQ5-j55lkxA/s200/earth-story_2d_cmyklrg.gif" width="200" /></a>Naturally, I looked up the rest of the documentary on youtube, and lo and behold found a <a href="http://www.youtube.com/user/KurdstanPlanetarium">user's channel</a> with virtually all of them available for ready consumption. I get easily addicted to geo-documentaries that are well presented, and Earth Story has an eloquent Englishman (zoologist Aubrey Manning), beautiful locations and brilliant animations, all prerequisites for a good doc. The series is well structured, with each part highlighting a piece of a particular whole of the history of Earth in geological terms, whilst building a story around revelations about certain phenomena. It has something for everyone, be you a geoscientist of one of the 4 major spheres, or an interdisciplinary. Without further ado, below is a sampling of the available episodes:<br />
<br />
<center><br />
<iframe allowfullscreen="" frameborder="0" height="390" src="http://www.youtube.com/embed/YYETGJSI568" title="YouTube video player" width="480"></iframe></center>This part on Climate change examines Pleistocene glacial advances. Some of the interesting things you'll be informed about include coral reef terraces, foraminifera, smoothed tillite, Carbon cycle & the Carboniferous, Milankovitch cycles, and my favorite of using ice-core samples to reveal Pb atmo concentration during Roman times.<br />
<br />
<br />
<center> </center><center><iframe allowfullscreen="" frameborder="0" height="390" src="http://www.youtube.com/embed/qaKTSowe3wE" title="YouTube video player" width="480"></iframe></center>This part on Deep time discusses topics such as unconformities, geothermal gradient, ammonites, radioactivity's role in geochronology, pre-Earth meteorites, Archaean cratonic pillow basalts, lithified mud pools.<br />
<br />
<br />
<center> <iframe allowfullscreen="" frameborder="0" height="390" src="http://www.youtube.com/embed/AOpwUqumXZ0" title="YouTube video player" width="480"></iframe></center>This part about volcanoes and the lithosphere examines mantle plumes, plate tectonics, seismic anisotropy, isostatic depression & rebound, mantle mineralogy, mantle convection, the Deccan Traps, Curie point.<br />
<br />
<br />
<center> <iframe allowfullscreen="" frameborder="0" height="390" src="http://www.youtube.com/embed/L_FcVtLocuk" title="YouTube video player" width="480"></iframe><br />
</center>This part on mountain formation looks into sea floor uplift, buoyant crust, slickensides, Gondwana's breakup, crustal thickening/thinning, geodesy, lithospheric flexure, serrate/entire leaf edges.<br />
<br />
Above is just a small sample of the entire series. Thanks to Kurdistan Planetarium for supplying the videos online. Readers, enjoy!<br />
<br />
Additional Info:<br />
<ul><li><a href="http://www.geology.wisc.edu/courses/g112/mtn_roots.html">University of Wisconsin @ Madison - Underneath the Mountains</a></li>
<li><a href="http://www.open2.net/therulesoflife/rol_welcome.html">The Rules of Life - Welcome from Aubrey Manning</a></li>
<li><a href="http://richarddawkins.net/videos/3390-richard-dawkins-and-aubrey-manning">Aubrey Manning discussion with Richard Dawkins</a></li>
</ul>Malcolm V Lhttp://www.blogger.com/profile/00126268490488546890noreply@blogger.com0tag:blogger.com,1999:blog-2188731877707108811.post-69057714821856310042011-03-15T11:27:00.000-07:002011-03-15T11:27:19.937-07:00My day @ The Western Division of the Canadian Association of Geographers<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhjom72A85yR8dsX4KhPk0tm6iSJPGJLj6mu4hjPP3euEOHD7MI10NSBk_ko5CJ5PgRwyw8TAU3ZlnHGYwpUx12E7V0PVPQFQ6yBV0KI7xxD-kDoK8PY5hrtuawgA6sMaiuEpKQ6OvYqAI/s1600/wdcag2011.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhjom72A85yR8dsX4KhPk0tm6iSJPGJLj6mu4hjPP3euEOHD7MI10NSBk_ko5CJ5PgRwyw8TAU3ZlnHGYwpUx12E7V0PVPQFQ6yBV0KI7xxD-kDoK8PY5hrtuawgA6sMaiuEpKQ6OvYqAI/s1600/wdcag2011.jpg" /></a></div>On Saturday, March 12 I attended an interesting conference, the Western Division of the Canadian Association of Geographers, with plenty of excellent presentations that both faculty and grad students from a multitude of BC universities. There were plenty of interesting topical presentations to choose from, and with only an 8 hour stretch to fit in nearly 80 presentations, I had to choose 1 out of a possible 6 for every 20 minute time slot. Thus I'm having to send a lot of follow-up emails to those presenters I missed but wanted to hear their findings. One regret is that I wasn't able to catch much of the presentations on BC cordilleran glaciation, but luckily the lunch intermission allowed me to chat with some students on their findings and field experiences.<br />
<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: left; margin-right: 1em; text-align: left;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjoNX7Ei88fZZ1GwS90RQIZTelhJ2Yw2VWlW_YgKoMW7z7V8qtJJ4JBMM9QpK250As3nyzn9f0f7dcwQQblrc_Kp_VaOS0NbUPV_gAbohqqnRYcro_G6JX5YUgWSXBu8E_bV0o8cr1oywI/s1600/Untitled.png" imageanchor="1" style="clear: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="233" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjoNX7Ei88fZZ1GwS90RQIZTelhJ2Yw2VWlW_YgKoMW7z7V8qtJJ4JBMM9QpK250As3nyzn9f0f7dcwQQblrc_Kp_VaOS0NbUPV_gAbohqqnRYcro_G6JX5YUgWSXBu8E_bV0o8cr1oywI/s320/Untitled.png" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Figure showing hydrologic response in a coastal western hemlock <br />
watershed. John Martin's investigations found that infiltration of <br />
precipitation is excellent, as the nature of the soil allows for a high <br />
hydraulic conductivity & porosity. Thus heavy rainfall doesn't result <br />
in much overland flow, at least not until the subsurface reaches <br />
saturation, and shallow depressions overtop.</td></tr>
</tbody></table><br />
I was able to catch presentations on GIS modeling of landslides, soil loss, and slope mapping of rugged terrain, in addition to my boss's talk on the decrease of agricultural land in Surrey, BC. He showed some maps I digitized, contrasting 30 years of shifting and merging agricultural lots and their tangible erosion in favor of RCI development. Most of the others I attended were on wetland hydrology and <a href="http://en.wikipedia.org/wiki/Lotic">lotic ecosystems</a>. The hydro presentations were quite technical in terms of highlighting their results, and quite advanced in terminology, but amazingly I found myself understanding most of what was said. That I attribute to my excellent Hydrology professor (who was one of the presenters), plus the presenters ability to define the important elements in their work. The only one that threw me for a loop was the aeolian physics of sand particles of a vegetated dune, and the subsequent quadrant mapping of their behavior during microclimate wind eddies & gusts.<br />
<br />
Thanks to my university's geography department, the cost of the conference was covered, and I will direct the reimbursement to <a href="https://www.mercycorps.org/donate/japan">relief of the earthquake/tsunami disaster in Japan</a>. Below is a list of the presentations I attended with, of course, my university profs in bold (gotta represent the alma mater):<br />
<ul><li>Connie Chapman (University of Victoria) - <i>Turbulent airflow and sediment transport over a vegetated foredune, PEI National Park</i></li>
<li><b>Parthiphan Krishnan (Kwantlen Polytechnic University) - <i>A GIS for Municipally Enabled Sustainable Agriculture</i></b> </li>
<li>Terence Lai (Simon Fraser University) - <i>Simulation of Urban Landslides: Cellular Automata approach</i></li>
<li>Laurens Bakker (Simon Fraser University) - <i>Spatial disaggregation of the Universal Soil Loss equation using Cellular Automata approach</i></li>
<li>Brandon Heung (Simon Fraser University) - <i>Automated procedure for digital landscape classification based on DEM data</i></li>
<li>Sarah Howie (Simon Fraser University) - <i>Vegetation variation across lagg forms of raised bogs in coastal BC </i></li>
<li><b>John Martin (Kwantlen Polytechnic University) - <i>The Hydrologic response of a small forested swamp complex, North Vancouver BC</i></b></li>
<li><i> </i>Yue-Ching Cheng (Simon Fraser University) -<i> Ins and Outs of Burns Bog: A look into the water balance of a large ombrotrophic bog in the Fraser Valley</i></li>
<li><b>Jan Thompson (Kwantlen Polytechnic University) - <i>Management of small water storages: A case study of small farm dams in New Zealand </i></b></li>
<li>Steven Marsh et al (University of the Fraser Valley) - <i>Variation of Fraser River, Kanaka Creek, and Silver Creek geochemistry</i></li>
<li>Maureen Attard (Simon Fraser University) - <i>Progress towards acoustic suspended sediment transport monitoring: Fraser River</i></li>
<li>Jessica Craig (University of Victoria) - <i>Dendroglaciological investigations at South More glacier, northern BC coast mountains</i></li>
</ul><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg9zEEhe7so7fsHtp8JYrXo0x6nac4xFYDxjar5xQdbnUDv37cdDdnq1NqOFfTWhD9XlhXVWOYZP5hZksiu5bfO9Rp7jQHVIQmPv2jMxw4i0DzKT_r12OC6qIuiRAAF5FHGn4yXUFE0KAM/s1600/tukitukicatch.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="235" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg9zEEhe7so7fsHtp8JYrXo0x6nac4xFYDxjar5xQdbnUDv37cdDdnq1NqOFfTWhD9XlhXVWOYZP5hZksiu5bfO9Rp7jQHVIQmPv2jMxw4i0DzKT_r12OC6qIuiRAAF5FHGn4yXUFE0KAM/s400/tukitukicatch.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><div style="margin-bottom: 0cm;">The study area in Jan Thompson's research into small farm dams in New Zealand (North Island). 39°58.218'S 176°19.850'E in Google Earth will place you around the highlighted watersheds, and by adjusting aspect you can see the drainage regime ultimately has its headwaters in the Ruahine Range foothills. Farmers with small dams (under 4m depth) gather their water mostly from first order streams, and Jan's investigations attempt to ascertain the cumulative effect these volumes will have on the larger whole downstream within the dendritic network, how they will alter the hydrology in regards to water quantity, water quality, downstream sediment transfer, and channel morphology.</div></td></tr>
</tbody></table>I learned lots of new things, not only about technical terminology and equipment used in the field, but also on the sociopolitical state of the environment on scales small and large. With food prices increasing worldwide, food security is coming to the forefront as an increasingly acute issue. In regards to equipment I saw utilized by researchers, I had never heard of using a pharmaceutical device called a <a href="http://www.wenglor.com/">Wenglor sensor</a> to count grains of sand, or a device called the <a href="http://en.wikipedia.org/wiki/Acoustic_Doppler_Current_Profiler">ADCP</a> (Acoustic Doppler Current Profiler); nor had I heard of certain equations, such as the Fernandez-Luque and van Beek equation. In essence, attending this conference has given me some extra homework to do, but that is all welcome cuisine for the cranium of this geo information junkie.<br />
<br />
Additional Info:<br />
<ul><li><a href="http://www.sfu.ca/wdcag2011/">Western Division of the Canadian Association of Geographers <span style="font-size: small;">2011 Annual Meeting</span></a></li>
<li><a href="http://www.burnsbog.org/bog/">Burns Bog Conservation Society</a></li>
<li><a href="http://en.wikipedia.org/wiki/Cellular_automaton">Cellular Automata</a></li>
<li><a href="http://books.google.ca/books?id=1AsypwBUa_wC&pg=PA75&lpg=PA75&dq=Fernandez+Luque+and+Van+Beek+Erosion+and+transport+of+bed-load+sediment&source=bl&ots=4iPCyoeKU-&sig=5To0Y42_RHd8hdKLrc6YtzQViYk&hl=en&ei=x6h-Tfb6CYvtrAGz2bCWCQ&sa=X&oi=book_result&ct=result&resnum=3&ved=0CCUQ6AEwAg#v=onepage&q=Fernandez%20Luque%20and%20Van%20Beek%20Erosion%20and%20transport%20of%20bed-load%20sediment&f=false">Sedimentation Engineering google book </a></li>
</ul>Malcolm V Lhttp://www.blogger.com/profile/00126268490488546890noreply@blogger.com1tag:blogger.com,1999:blog-2188731877707108811.post-40331685033065588482011-03-02T23:20:00.000-08:002011-03-02T23:20:10.702-08:00Field photo follow-upThis is a follow-up to the field photos I posted a month ago, and my best explanation of their origins and processes.<br />
<hr />First is a landform located in a gravel quarry in <a href="http://en.wikipedia.org/wiki/Squamish,_British_Columbia">Squamish, BC</a> (49° 43.899'N 123° 06.250'W). Access is via Sea-Sky highway #99. Take a right onto Mamquam Rd. near the Canadian Tire, and travel for 2km up to the quarry entrance, which will be on your left. The geomorphology of what you see below was created when the land in the area was much closer to sea level during the Pleistocene epoch. The environment of deposition was transitional, specifically a delta, represented by visible <a href="http://en.wikipedia.org/wiki/River_delta#Sedimentary_structure">topsets & foresets</a>. Bottomsets are presumably there, but have not been exposed by the quarrying. Since the region experienced glaciation during the Pleistocene, isostatic depression was the primary force for lowering the area to near sea level, and Holocene rebound has taken it up to its current 100m elevation. Evidence of glaciation is apparent from the mantle of glacial till, which overrode the underlying sedimentary structure during a later advance.<br />
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgzwuriIpz9Nl1y1FzK84MMrqosoaQ46CS6YGQ24pgEwfRNyn1thTI9P2A0sGjJlotcLmaJbAwqzqVjVECVHblH0JxrrFA01WbAhTJ0Cat_Ddhq0Cvdggp6QoBdeXcGN9wxrp1IWn-VKCI/s1600/Untitled.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="252" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgzwuriIpz9Nl1y1FzK84MMrqosoaQ46CS6YGQ24pgEwfRNyn1thTI9P2A0sGjJlotcLmaJbAwqzqVjVECVHblH0JxrrFA01WbAhTJ0Cat_Ddhq0Cvdggp6QoBdeXcGN9wxrp1IWn-VKCI/s400/Untitled.png" width="400" /></a></div>Second is an up-close shot of a granodiorite rockface that includes a granulite xenolith shaped somewhat like a tooth (49° 20.025'N 123° 07.124'W). The rockface is tremendously chemically weathered, turning it into <a href="http://en.wikipedia.org/wiki/Saprolite">saprolite</a>. This chemical weathering mechanism is not indicative of the current mid-latitude temperate climate of BC, but is indicative of when BC was placed in a more equatorial latitude in its late Paleozoic-early Mesozoic paleogeography. The granodiorite is typical of so much of southwest BC, as it is a plutonic extension of the Coast Range batholith that encompasses the region, and by subsequent erosion has been thoroughly exposed. During its subduction-driven intrusion, the batholiths extensions baked overlying sedimentary & igneous units, and metamorphosed granulite 'polka-dots' became inclusions within much of the granodiorite seen at the surface. Touring Greater Vancouver, one can spot many instances of aggregate that uses the granodiorite w/ granulite xenoliths manufactured for construction and landscaping.<br />
<br />
<u>Access to this rockface:</u> Follow Trans-Canada highway #1 west in North Vancouver. Take the Taylor Way exit and make a left turn onto Taylor Way. Head south for nearly a kilometer, and make a left onto Keith Rd. Follow Keith Rd all the way until you pass under the highway, then park and walk down a relatively steep trail to the Capilano riverside.<br />
<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhgJDoLplK4-SDu4KGek_RTk3h2YC0hpM-4LtojegAY1BPVDdwm0XP1Blgw0MONg92MJz39V2q5Nr1pxBKBDGZTc1sr9QmQeE-C_cgl21bBTvqw-AlZJlPYBtlgXK-uUjkzix8tS1-rm98/s1600/Picture+002.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="316" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhgJDoLplK4-SDu4KGek_RTk3h2YC0hpM-4LtojegAY1BPVDdwm0XP1Blgw0MONg92MJz39V2q5Nr1pxBKBDGZTc1sr9QmQeE-C_cgl21bBTvqw-AlZJlPYBtlgXK-uUjkzix8tS1-rm98/s400/Picture+002.jpg" width="400" /></a></div>A couple more field photos will be posted soon, and this time explanations will be included forthwith. And just a small aside, a small rant: Anyone putting up paleogeographic maps on the web please, for the love of god, include major demarcations of latitude (equator, 30°, 60°, poles). It makes a world of difference in deducing paleoclimates.<br />
<br />
Additional Info:<br />
<ul><li><a href="http://jan.ucc.nau.edu/%7Ercb7/globaltext2.html">Global Paleogeography</a></li>
<li><a href="http://www.sciencedirect.com.ezproxy.kwantlen.ca:2080/science?_ob=ArticleURL&_udi=B6VBC-46R5NPT-2&_user=1898427&_coverDate=10%2F31%2F2002&_alid=1662866868&_rdoc=1&_fmt=high&_orig=search&_origin=search&_zone=rslt_list_item&_cdi=5923&_sort=r&_st=13&_docanchor=&view=c&_ct=19&_acct=C000055247&_version=1&_urlVersion=0&_userid=1898427&md5=9d7e036d267690e5d32f149798e8b941&searchtype=a">Younger Dryas readvance in <span class="hit">Squamish</span> river valley, southern Coast mountains, British Columbia</a> </li>
<li><a href="http://www.sciencedirect.com.ezproxy.kwantlen.ca:2080/science?_ob=ArticleURL&_udi=B6VGS-44JF5W4-M&_user=1898427&_coverDate=01%2F31%2F2002&_alid=1662866868&_rdoc=2&_fmt=high&_orig=search&_origin=search&_zone=rslt_list_item&_cdi=6046&_sort=r&_st=13&_docanchor=&view=c&_ct=19&_acct=C000055247&_version=1&_urlVersion=0&_userid=1898427&md5=8d6c966c0b8d087558fc50ec48bca531&searchtype=a">Readvance of glaciers in the British Columbia Coast Mountains at the end of the last glaciation </a></li>
</ul>Malcolm V Lhttp://www.blogger.com/profile/00126268490488546890noreply@blogger.com0tag:blogger.com,1999:blog-2188731877707108811.post-49385313470939244162011-02-23T08:48:00.000-08:002011-02-23T08:48:01.668-08:00Papers I'm reading: Declining sand dune activity in the southern Canadian prairies<div style="font-family: inherit;"><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjSkuzD72xRyuDl3C471imaHRuJ-n2Ib54T9LW8jitMr6Py3xsGTzMMVbJudWf3p95ajgu9V84X7e0AkMXRZgghlf-mvkwuVsmVXG5ooc1Q6YM-Vl5cfSM9fUWi1S9f3Hv2JQUkjgffh4c/s1600/DSC_0759.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="300" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjSkuzD72xRyuDl3C471imaHRuJ-n2Ib54T9LW8jitMr6Py3xsGTzMMVbJudWf3p95ajgu9V84X7e0AkMXRZgghlf-mvkwuVsmVXG5ooc1Q6YM-Vl5cfSM9fUWi1S9f3Hv2JQUkjgffh4c/s400/DSC_0759.jpg" width="500" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><div><i>"Visually, the dunes were incredible. They were at least four to five meters in height standing from the top, and there were about four-five rows of dunes. Most of them ran north-south in length. The wind picked up while we were there and I can understand how the dunes are moving so many mm's/cm's each year. The area surrounding the dunes was very desert-like (we spent one night nearby and I managed to get a cactus stuck in my foot, hurt very much). We could also hear the coyotes howl all night and in the morning witnessed several hawks flying by. The area was extremely dry, so much so that I even came across a sort of animal grave yard at the far north part of the main dunes. There was several skeletal remains of what I assumed to be cattle, though the bones were quite small and could have been deer. There were also plenty of little bugs wandering around the dunes, leaving their tracks in the sand, though I couldn't say what kind of bugs they were (although there were many "tiger bugs" I think that's what they are called)."</i></div></td></tr>
</tbody></table>The above excerpt is courtesy of an aspiring journalist friend who has a keen instinct for the geographic/geologic, detailing an experience among some spectacular sand dunes: <a href="http://writersfidelity.blogspot.com/">Writer's Fidelity</a><br />
<br />
<span id="goog_1168692332">Her description of majestic dunes in southern Saskatchewan segues into the latest dozen-page intellectual nugget, coming courtesy of the <a href="http://www.blogger.com/goog_1241320807">Journal of Aeolian Research</a>. The article is titled <b>Declining sand dune activity in the southern Canadian prairies: Historical context, controls and ecosystem implications</b>, authored by Chris Hugenholtz, Darren Bender, and Stephen Wolfe. The paper goes into detail about how the patchy sand dunes located in Southeast Alberta-Southwest Saskatchewan have been seeing a slow but steady decline for the past hundred years or so, and how this decline affects the ecosystem balance and the organisms that reside in the relict landforms:</span></div><blockquote style="font-family: inherit;"><span style="font-size: x-small;">Sandhills are islands of biodiversity in the southern Canadian prairies that sustain habitat for many rare and endangered species. These unique areas consist of large expanses of dune fields now mostly stabilized by grassland vegetation. Historically, the number of active dunes has decreased significantly due to vegetation stabilization, resulting in a dramatic decline of open-sand habitat for a variety of dune-dependent species. Without a certain level of wind erosion, opportunities for establishment of early-stage, species-rich vegetation types are diminished and open-sand habitat decreases by encroachment of the surrounding grassland vegetation. The current trend of dune stabilization, however, implies that wind erosion is decreasing, thereby threatening the continued existence of a variety of dune-dependent plants, arthropods and vertebrates, as well as other less-specialized species that benefit indirectly from these habitats. By reviewing factors contributing to the historical decline of active dunes, as well as the ecological implications of dune stabilization, the aim of this paper is to establish the biophysical context for new land management strategies that conserve valued landscape components, such as active dunes, and the processes therein. As dune stabilization continues management interventions will be required to sustain or re-establish open sand and the species that rely on these habitats.</span></blockquote><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; font-family: inherit; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg2Bag7fR295Km9GtsaDLPJ7UbSCZTIWP9BLZ5zuKgwc1jQLIYd_zsEvIVTQwDC0_4PONodMoC2bXRxKRZv-EXmQ0Ur7i8_3dJZ9y4hq2gNEVf2N8WBx2vW8snn1ZbtgnbdeewuLIcVarc/s1600/blowouts.png" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="232" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg2Bag7fR295Km9GtsaDLPJ7UbSCZTIWP9BLZ5zuKgwc1jQLIYd_zsEvIVTQwDC0_4PONodMoC2bXRxKRZv-EXmQ0Ur7i8_3dJZ9y4hq2gNEVf2N8WBx2vW8snn1ZbtgnbdeewuLIcVarc/s320/blowouts.png" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Blowout dunes of Great Sand Hills, SW Saskatchewan</td></tr>
</tbody></table><div style="font-family: inherit; margin-bottom: 0cm;">You can take a look in Google Earth @ 50° 41.326'N 109° 17.069'W; most of the dunes are of the parabolic variety. The dunes are essentially relics from end of Pleistocene ice a<span style="font-size: small;">ges, notably the <a href="http://en.wikipedia.org/wiki/Wisconsinan_glaciation">Wisconsonian</a>, that have persisted due to a semi-arid precipitation regime and infrequent prolonged droughts typical of the prairies in SE Alberta/SW Saskatchewan. The southern prairies exhibit heavily glaciated terrain, wherein these glaciomarine-glaciodeltaic-glaciofluvial sands were derived from meltwaters at glacial fronts</span><span style="font-size: small;"><span style="font-weight: normal;">, and the region was subjected to <a href="http://en.wikipedia.org/wiki/Katabatic_wind">katabatic winds</a> flowing down off the front. The cold, sweeping winds were an excellent local atmospheric mechanism for sorting the sand into dunes.</span></span></div><div style="font-family: inherit; font-weight: normal; margin-bottom: 0cm;"><br />
</div><div style="font-family: inherit; margin-bottom: 0cm;">The paper shows dune activity in 1900's declining due to dune stabilization via vegetation. Provincial action plans to reduce soil erosion has had a lateral effect upon the fragile ecosystem of the dunes and their plant & animal inhabitants. Thus in many ways, it is a "Damned if you do, Damned if you don't" issue, with anthropogenic activities being vastly responsible for currently affecting dune stabilization or proliferation. If left alone, the current climate change trend towards warming & disruption of precipitation regimes would likely lead to an increase in dune areal coverage, but only if decade-long droughts consistently occur. How does that work, though? If humans don't interfere with the dunes, our interference in the atmosphere will allow them to flourish?? In any case, the latter is already assured due to the lag of GHG's.<br />
<br />
<div style="font-family: inherit; margin-bottom: 0cm;"><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: left; margin-right: 1em; text-align: left;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiPSnSk4Xjlan2-psr4D60ywQNvUMSUnsUFh1fEWl2L8NGdGBlS0FuVbYQJ_t5X62JNvM505w0WLmLhiy87zaBr5qnGrm8TOUhrXDGBnkQp3RfpGmYqXnSalrpekdX1O8JSFKPQZTqjdWA/s1600/grsa-kangaroorat2006.jpg" imageanchor="1" style="clear: left; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="150" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiPSnSk4Xjlan2-psr4D60ywQNvUMSUnsUFh1fEWl2L8NGdGBlS0FuVbYQJ_t5X62JNvM505w0WLmLhiy87zaBr5qnGrm8TOUhrXDGBnkQp3RfpGmYqXnSalrpekdX1O8JSFKPQZTqjdWA/s200/grsa-kangaroorat2006.jpg" width="200" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Ord's Kangaroo rat on sand hills</td></tr>
</tbody></table><div style="font-weight: normal; margin-bottom: 0cm;">The real crux of the paper outlines what the implications are for the endemic flora & fauna. Since sand transport is effectively eliminated when vegetation cover exceeds 15%, the fragility of the dunes is acute due to the presence of rare, endangered species that habituate on blowout dunes. Within the paper there is listed over a dozen species of plants and animals in danger of extirpation. Examples include liverworts, arthropods, and the unique <a href="http://en.wikipedia.org/wiki/Ord%27s_Kangaroo_Rat">Ord's kangaroo rat</a>. The latter is under threat due to dune stabilization allowing predators to corner the rats into an increasingly smaller territory with less space for effective burrowing. The dunes are stabilized by vegetation in a positive feedback mechanism that allows <a href="http://en.wikipedia.org/wiki/Ruderal">ruderal</a> plants to proliferate on the dune perimeter by increasing surface roughness and changing soil properties to suite further veg expansion → if this goes too far, it will push out endangered dune-loving species like Ord's rat. The endemic animal plays a key role in the food web ecology of the southern prairies, extending an indirect influence outside the dune hills.</div><div style="font-weight: normal; margin-bottom: 0cm;"><br />
</div>Co-operative efforts are underway in the prairies to allow some wind-driven erosion to facilitate natural dune migration & extent, though there is some back-forth wrangling with farm associations that prefer stabilization that protects soil resources. When looking at, for instance, the <a href="http://en.wikipedia.org/wiki/Leader,_Saskatchewan#Attractions">Great Sand Hills near Leader</a> using Google Earth, you can see how farm lots completely surround the dunes. <span style="font-weight: normal;">To conclude my observations, I generally get 3 things out of a peer-reviewed paper: </span><br />
<ol><li><span style="font-weight: normal;">A new term learned; in this case it was <i>ruderal</i></span></li>
<li><span style="font-weight: normal;">A new question raised; in this case <i>how does food security fit into the mix? If prairie farmers are wishing to avoid migrating dunes overtaking their lots, how do we address their concerns while allowing the dunes to flourish?</i></span></li>
<li><span style="font-weight: normal;">A new realization; </span>in this case <i>connecting elements to learn how glaciers can form picture-perfect dunes. I knew of katabatic winds, I knew that wind is the greatest terrestrial sorter, and that glaciofluvial is second greatest & capable of transporting & sorting fine sand. Integrate the mechanisms together to make the dunes?....I did not realize that til now.</i></li>
</ol>Additional Info:<br />
<ul><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjloSOn-6xuJ6D2cillA1G6D9a9FY0iTHqY9fO48AikcLsSDoymkbddzXR2o-QS6qRII7bAp7g31XJWaheeH_nIC4LU4Zyqs4nucoNMoizS-slCvizM617gY_8x5q555PHmC9MkV_D-Ymk/s1600/litho.jpg" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjloSOn-6xuJ6D2cillA1G6D9a9FY0iTHqY9fO48AikcLsSDoymkbddzXR2o-QS6qRII7bAp7g31XJWaheeH_nIC4LU4Zyqs4nucoNMoizS-slCvizM617gY_8x5q555PHmC9MkV_D-Ymk/s1600/litho.jpg" /></a>
<li> <div style="margin-bottom: 0cm;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEijssb86T6hC4srfwqCfVtzJRWOkcOtPh_h94m_S8oUyH8zenUyeYv6Te6hhkUkAsOVECnQZ_YjmYoo_DRX3m9aJ-y-KEHAZQjFArDPFP7jC6ZY1nFnFJhhhPd1Y4ukDcssKvomEuv2vic/s1600/dune%2525.png">Chart of Declining sand dune activity for various dune clusters (1925 - 2005)</a></div></li>
<li><a href="http://www.environment.gov.sk.ca/2007-104GreatSandHillsEnvironmentalStudy">Government of Saskatchewan - Great Sand Hills Environmental Study</a></li>
<li><a href="http://writersfidelity.blogspot.com/">Jessica Bell - Writer's Fidelity</a></li>
<li><a href="http://www.aeolianresearch.org/">ISAR - International Society for Aeolian Research </a></li>
<li><a href="http://www.sciencedirect.com.ezproxy.kwantlen.ca:2080/science?_ob=ArticleURL&_udi=B8JK0-50F99SC-1&_user=1898427&_coverDate=11%2F30%2F2010&_alid=1650621328&_rdoc=1&_fmt=high&_orig=search&_origin=search&_zone=rslt_list_item&_cdi=43740&_sort=r&_st=13&_docanchor=&view=c&_ct=56&_acct=C000055247&_version=1&_urlVersion=0&_userid=1898427&md5=650e5b75cee9f895c7de7e7c46c0a966&searchtype=a">ScienceDirect - Declining sand dune activity in the southern Canadian prairies (Nov 2010)</a></li>
</ul><div class="separator" style="clear: both; text-align: center;"></div><ul></ul></div></div><div style="margin-bottom: 0cm;"></div><div style="margin-bottom: 0cm;"></div>Malcolm V Lhttp://www.blogger.com/profile/00126268490488546890noreply@blogger.com2tag:blogger.com,1999:blog-2188731877707108811.post-55282083937247383332011-02-17T10:28:00.000-08:002011-02-17T10:28:53.054-08:00Accretionary Wedge #31: "What the heck?!"<div style="text-align: left;">This will be my first contribution to the <a href="http://theaccretionarywedge.wordpress.com/">Accretionary Wedge</a> blog carnival, and as a senior undergrad the topic suites me perfectly: <b>What geological concept or idea did you hear about that you had no notion of before (and likely surprised you in some way)?</b></div><div style="text-align: left;"><br />
<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEieY0Gi_rv0fgwDOkr6w0XkPXOgDQVJfa4yHFAqMIvi6Ox2cwGqZXtjzXrS1XAUOIUQ28_lRFfePp6u_MuNoNlYBK0eygwhn3UGE9j_JUpZrZ08B5e41qz5EdQ2lDLIIVGMx5YBi2Bi2Do/s1600/Picture.jpg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEieY0Gi_rv0fgwDOkr6w0XkPXOgDQVJfa4yHFAqMIvi6Ox2cwGqZXtjzXrS1XAUOIUQ28_lRFfePp6u_MuNoNlYBK0eygwhn3UGE9j_JUpZrZ08B5e41qz5EdQ2lDLIIVGMx5YBi2Bi2Do/s1600/Picture.jpg" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">basic concept of gravity<br />
when applied to rock density</td></tr>
</tbody></table>Thanks to <a href="http://jazinator.blogspot.com/2011/01/accretionary-wedge-31-call-for-posts.html">Jim Lehane of the Geology P.A.G.E.</a> for hosting AW#31</div><div style="text-align: left;"></div><br />
For my first two years at uni, previously unknown concepts were a given on a weekly basis. But as my studies get more in-depth, the concepts are becoming more esoteric and/or specific. One concept from those early years comes strongly to mind, as it took me some time to grasp before the metaphoric light-bulb turned on: <u>Gravity Anomalies</u><br />
<u> </u><br />
My physics teachers would drill it into us that acceleration due to gravity is a constant (@ <span style="white-space: nowrap;">9.807 m/s<sup>2</sup></span>). GRAVITY, G, IS A CONSTANT! ad nauseum. Then I was eventually presented with an alternate view of the consistency of the constant by my geophysics teacher. I, in my infinite lack of wisdom, and stubbornly sticking by what was told to me by my physics teachers, shirked off his silly idea of minute differences in gravity based on crustal thickness and rock types. I didn't really understand the mechanics of it the way he explained it, and it was never really tested on us students.<br />
<br />
The true revelation came during a summer volunteer expedition with a local CGS glaciologist. As one of three heading up to the <a href="http://www.clubtread.com/sforum/topic.asp?TOPIC_ID=17955">Matier Glacier</a> within <a href="http://www.env.gov.bc.ca/bcparks/explore/parkpgs/joffre_lks/">Joffre Lakes park</a>, I got a taste of what experts do, and what instruments they use to analyze receding glaciers and the mountains they rest on. I found out that one such device we lugged up to the top, a <a href="http://en.wikipedia.org/wiki/Gravimetry#Microgravimetry">microgravimeter</a>, measures the gravitational field at a point. So the glaciologist operated it, got the reading in <a href="http://en.wikipedia.org/wiki/Gal_%28unit%29">milligals</a>, and I stood there dumbfounded. He was gracious enough to explain to me the concept of gravity anomalies...how it relates to crustal properties (such as thick, light mountain roots & thin, dense old oceanic trenches), and how we get the <a href="http://en.wikipedia.org/wiki/Bouguer_anomaly">Bouguer anomaly</a>, derived from measurements/corrections.<br />
<blockquote><span style="font-size: x-small;"><i>"Rocks have different densities, eg. felsic - ultramafic, and compression of the crust via plate tectonics can thicken the crust, developing structural mountains with or without igneous intrusions. These mountains have thick roots, sometimes 30+km from peak - basement. When such a thick mass is composed primarily of lighter granites, its lighter density is less of an attraction than when compared to a thinner, denser mass of heavier basalts. Denser basalts are found near subduction zones, especially above deep trenches. The phenomenon is comparable on continents as well: The Deccan Traps of Maharashtra measure a noticeable difference in gravity compared to the Himalaya ranges in Uttarakhand."</i></span></blockquote><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg_oDUPMnUigbHzWQTse67J7A1HmKfpJD7XyzTp9gfirzP7Cg0waEzjo9UP2qs1I1xH8Bg5QhLSdv_ihUVmHbYtI9_-L_dXiIdIh0A1T1poGIj85I59HXeUEPE8e50ipwmB12xQdYb8gL0/s1600/Picture+001.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="237" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg_oDUPMnUigbHzWQTse67J7A1HmKfpJD7XyzTp9gfirzP7Cg0waEzjo9UP2qs1I1xH8Bg5QhLSdv_ihUVmHbYtI9_-L_dXiIdIh0A1T1poGIj85I59HXeUEPE8e50ipwmB12xQdYb8gL0/s320/Picture+001.jpg" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Upper Joffre lake. Behind would be the tongues of the Matier Glacier.<br />
This is where I learned about gravity anomalies, luckily not by tumbling down to the tarn</td></tr>
</tbody></table><div class="separator" style="clear: both; text-align: center;"></div><div class="separator" style="clear: both; text-align: center;"></div>Thus I was enlightened to a concept that had previously been muddled in my brain. I've even had a couple opportunities to apply it to my personal and work projects (ie. <a href="http://pumicecastle.blogspot.com/2011/01/on-geology-topography-of-cornwall.html">Cornwall geology post</a>). It's become an increasingly seen concept in higher level textbooks I've perused, and more and more diagrams & cross sections that have caught my eye combine topographical profiles and Bouguer anomaly milligal values (example below).<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgv1ljBAXw8n6w-vCu81f3o_hTpMYVTwyAHDH0A82ht2kmXFcd3iqW3nKrm1RDfX3c-uzzbN4Yk3pb61DgkF3dYZpXMceaYs5pyP9ilzbeoOws2TTC23Bheqoucwi7kHyhfEk3SIsZL294/s1600/usabouguer.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="230" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgv1ljBAXw8n6w-vCu81f3o_hTpMYVTwyAHDH0A82ht2kmXFcd3iqW3nKrm1RDfX3c-uzzbN4Yk3pb61DgkF3dYZpXMceaYs5pyP9ilzbeoOws2TTC23Bheqoucwi7kHyhfEk3SIsZL294/s400/usabouguer.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Simple profile showing Bouguer anomaly values with general topography across the US</td></tr>
</tbody></table>In retrospect, I wish I had a time machine, so I could go back and tell my junior undergrad self about how not to take anything for granted in the scientific studies. Geology always seems to smash preconceptions built up by the other science disciplines, and that's something I love about it. For anyone interested, Britain & Ireland geological survey's have done some extensive gravity surveying, and documented some interesting positive & negative zones. Check out the additional links for it.<br />
<br />
Additional Info:<br />
<ul><li><a href="http://en.wikipedia.org/wiki/Gravity_anomalies_of_Britain_and_Ireland">Gravity Anomalies of Britain and Ireland</a></li>
<li><a href="http://tin.er.usgs.gov/gravity/bouguer/">Bouguer gravity anomaly for the contiguous US</a></li>
<li><a href="http://www.sciencedirect.com.ezproxy.kwantlen.ca:2080/science?_ob=ArticleURL&_udi=B6V6M-489SVJ8-3N&_user=1898427&_coverDate=06%2F30%2F1990&_alid=1643003849&_rdoc=2&_fmt=high&_orig=search&_origin=search&_zone=rslt_list_item&_cdi=5818&_sort=r&_st=13&_docanchor=&view=c&_ct=1055&_acct=C000055247&_version=1&_urlVersion=0&_userid=1898427&md5=7751921d585749785ffbf413bf72a4b8&searchtype=a">Various gravity anomalies mapped in the Canadian Arctic</a></li>
</ul>Malcolm V Lhttp://www.blogger.com/profile/00126268490488546890noreply@blogger.com1tag:blogger.com,1999:blog-2188731877707108811.post-59510176019458476002011-02-14T09:47:00.000-08:002011-02-14T09:47:04.667-08:00Picking the best place to live, geologically speaking<div class="separator" style="clear: both; text-align: left;">I rarely get to have discussion with human geography students, but the natural hazards class I recently completed had a good spread of the physical geeks with the human geeks. One human friend mentioned how she lives in a neighborhood on the edge of a broad alluvial fan, and that her parents have little clue as to the potential dangers of living on such a precarious foundation protected only by modest dikes, which I might add have had increasingly shrinking freeboard values for the past two decades. The deflecting reason they gave her is that "developers would not have built here if it wasn't safe". </div><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh_cbjQUYnanA8s71d-y063EoZb4BO9Irfk491Q2ltX42EDN9kc9xKEYoBOvt2-ysJox3XHDLwCOkonwClRzy10Y_jOcuRViMbTsW94p2ZfDZZQR8Hf6g0cAKmU6d1CdZK2kUNKziY4kfA/s1600/efin1099l.jpg" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img border="0" height="183" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh_cbjQUYnanA8s71d-y063EoZb4BO9Irfk491Q2ltX42EDN9kc9xKEYoBOvt2-ysJox3XHDLwCOkonwClRzy10Y_jOcuRViMbTsW94p2ZfDZZQR8Hf6g0cAKmU6d1CdZK2kUNKziY4kfA/s200/efin1099l.jpg" width="200" /></a><br />
Oh no, they would. Developers hedge their bets, and most in our regional district tend to downplay the importance of geophysical reports. Developers will push through proposals with hard cash to get the required zoning, especially if the 'view' and location is something that will bring them big bucks. This is not to say that they will cut corners wherever possible, as most of the time construction is top-notch, corresponding to strict standards for quake-proofing and packing down the sediment if the foundation happens to be laid upon Holocene alluvium.<br />
<br />
Where is this post leading? Well, in my humble opinion prospective home owners have to take on some proactive responsibility themselves. Common sense dictates that the buyer beware, and there is no excuse for an educated westerner who does have the rights and the access to geophysical information to not take some time and look at it. Where I live in beautiful British Columbia, our own <a href="http://www.empr.gov.bc.ca/MINING/GEOSCIENCE/Pages/default.aspx">provincial division</a> of the Canadian geological survey has done some excellent work on investigating factors that determine how damaging certain natural hazards are in certain areas. Below you'll notice fragments of a poster that outlines the traffic-light approach to categorizing hazards: <br />
<div class="separator" style="clear: both; text-align: left;"></div><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgboXnW7UZ1dhZJkTrQOYcIYuTF4KSITaFv3Z1MVlC3tWODeSAmoaJXf9LhI8YeThv5QW08KJbt23NnGXyd_R6-ZlJ41bCTorZJ9nSyPJylpcF2_ZBMJUZsbPzuXgydiMpfmQ_v1tRjoBI/s1600/slopehaz.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="271" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgboXnW7UZ1dhZJkTrQOYcIYuTF4KSITaFv3Z1MVlC3tWODeSAmoaJXf9LhI8YeThv5QW08KJbt23NnGXyd_R6-ZlJ41bCTorZJ9nSyPJylpcF2_ZBMJUZsbPzuXgydiMpfmQ_v1tRjoBI/s400/slopehaz.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Slide hazard map of Greater Vancouver. <br />
Light green circles indicate known slide occurrences </td></tr>
</tbody></table><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh_I2X1JAPJmn2_eKtUxuPt1xpFd3Y8sDl1z4l6s-yEHC1njNH43AHyPdXs61XKjqSP3l7hfzvLP0vAibXWkSISp-kgjmdzbHF9uUG1rbgpxl613TmHTgJ5kV-GEBIWfvXP08aiZgSIxf0/s1600/eqliq.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="262" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh_I2X1JAPJmn2_eKtUxuPt1xpFd3Y8sDl1z4l6s-yEHC1njNH43AHyPdXs61XKjqSP3l7hfzvLP0vAibXWkSISp-kgjmdzbHF9uUG1rbgpxl613TmHTgJ5kV-GEBIWfvXP08aiZgSIxf0/s400/eqliq.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Liquefaction hazard map of Greater Vancouver.<br />
Red zones mostly correspond to deltaic and alluvial deposits</td></tr>
</tbody></table><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjcNsIFcgA_xg3jwzHz8vR3iVjtJPqCYhLEH0hvNYQ5dYU3OXFhRoOuhy1JOZaGzG-kHTRGWMEhbtVKWwOIGDa1MKnrLLhpt7CKQ8VrSRlKeY6wUL6OPOMreRhcje250aE_2hddJH-Hxpw/s1600/floodhaz.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="286" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjcNsIFcgA_xg3jwzHz8vR3iVjtJPqCYhLEH0hvNYQ5dYU3OXFhRoOuhy1JOZaGzG-kHTRGWMEhbtVKWwOIGDa1MKnrLLhpt7CKQ8VrSRlKeY6wUL6OPOMreRhcje250aE_2hddJH-Hxpw/s400/floodhaz.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Flood hazard map of Greater Vancouver.<br />
The red zones are deltaic and alluvial plains, and have experienced little uplift <br />
since the fill is mostly Holocene. The grey zones are Pleistocene glacial uplands,<br />
mostly till, and benefit from tens of meters of thickness + isostatic rebound </td></tr>
</tbody></table><table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgAIOfSO1zR-z3OH5tvA_VkjFTiyOGiRnkqCeMiVexCrTZQQi2lXOxmF0EzpBoxZnGnZOfEqNWLxckkcziGZRDEov9wAZfpXFFe3V0dufKblD0efnSFQep6sOtaQZFCq_4SBCBlgj9840g/s1600/cascadia_1700.jpg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img border="0" height="163" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgAIOfSO1zR-z3OH5tvA_VkjFTiyOGiRnkqCeMiVexCrTZQQi2lXOxmF0EzpBoxZnGnZOfEqNWLxckkcziGZRDEov9wAZfpXFFe3V0dufKblD0efnSFQep6sOtaQZFCq_4SBCBlgj9840g/s200/cascadia_1700.jpg" width="200" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Tsunami wake from Jan 26, 1700<br />
megathrust quake. Ghost forests <br />
attest to unbuckling of plates, <br />
causing meters of subsidence</td></tr>
</tbody></table>Looking at this one source of credible information already alleviates a lot of concerns a potential home owner would have, especially in our tectonically active region. Sure we haven't had a big one in living memory, but that doesn't mean we are out of any proverbial woods. On the contrary, the lack of moderate quake activity off the coast of Vancouver Island has led geophysicists to investigate and conclude that the Juan de Fuca plate & North America plate are locked at the shallow subduction contact, and tension is building to an inevitable unbuckling. Whether that results in one huge snap of a <a href="http://en.wikipedia.org/wiki/Megathrust_earthquake">megathrust</a> akin to the 1700 Cascadia quake, or a series of smaller unbuckling motions is yet to be seen.<br />
<div class="separator" style="clear: both; text-align: left;">I was asked if I chose where I live because it is among the safest spots in the region. I reside on the glacial uplands, on the crest of a street with a gentle slope. Alas, as a student with a limited budget and only part-time jobs, I cannot claim that I was so smart to have chosen such a safe spot. It's pure coincidence, I chose it because I could afford the rent. But I have dodged a bullet, so to speak, by digging for this knowledge and taking it to mind before I do make my first home purchase years from now. I've already compiled a short list of personal rules for where a home should be, to which additions will slowly be added:</div><ul style="text-align: left;"><li style="font-family: inherit;"><span style="font-size: x-small;">At least 300m from shore</span></li>
<li style="font-family: inherit;"><span style="font-size: x-small;">At least 50m asl</span></li>
<li style="font-family: inherit;"><span style="font-size: x-small; font-weight: normal;">Not adjacent to any slope greater than 25</span><span style="font-size: x-small;"><span style="font-weight: normal;">°</span></span></li>
<li style="font-family: inherit;"><span style="font-size: x-small;">Not on any faults, not even ones considered “inactive”</span></li>
<li style="font-family: inherit;"><span style="font-size: x-small;">Not on any META bedrock that has extreme foliation</span></li>
<li style="font-family: inherit;"><span style="font-size: x-small;">Not on any SED bedrock where bedding planes are poorly indurated</span></li>
<li style="font-family: inherit;"><span style="font-size: x-small;">Not within the boundaries of a 1 in 50 year floodplain</span></li>
<li style="font-family: inherit;"><span style="font-size: x-small;">Not within the boundaries of a 1 in 100 year floodplain if recent evidence has shown urban development has forced flow to concentrate, and thus freeboard values for dikes are consistently less than 2 feet </span></li>
<li style="font-family: inherit;"><span style="font-size: x-small;">Not on any foundation that has a layer that swells when saturated (ex. <a href="http://en.wikipedia.org/wiki/Bentonite">Bentonite</a>)</span></li>
<li style="font-family: inherit;"><span style="font-size: x-small;">Observe wind direction patterns if living on or near a sandy desert or high altitude snowy area, to avoid home being buried by windblown material</span></li>
<li style="font-family: inherit;"><span style="font-size: x-small;">Not on any bedrock that has a lens of limestone beneath (GPR should discover it), lest it dissolves and a sinkhole forms</span></li>
<li><span style="font-family: inherit; font-size: x-small;">Not within a radius of 300m from </span><span style="font-family: inherit; font-size: x-small;">the edge of a forest prone to fires. Consider making the perimeter of your property fuel-free</span> </li>
</ul>I know a few of these are not economically feasible, but I've tried to arrange them in what I consider their order of importance, and the first several are free provided some time and effort and some light education. The <a href="http://en.wikipedia.org/wiki/Ground-penetrating_radar">GPR</a> might not be an option, but if buying a $seven figure$ home, it's worth it for peace of mind. Above all else, look at the hazard history of the area you're moving into.<br />
<br />
I'm not touching on atmospheric hazards, but they should be looked into as well. They're kind of a big deal too.<br />
<br />
Additional Info: <br />
<ul><li><a href="http://www.iris.edu/hq/files/programs/education_and_outreach/aotm/5/2.Subduction_Rebound_Background.pdf">IRIS - Subduction Zone Plate Interaction</a></li>
<li><a href="http://pubs.usgs.gov/pp/pp1707/pp1707.pdf">USGS - The Orphan Tsunami of 1700</a></li>
<li><a href="http://gsc.nrcan.gc.ca/urbgeo/geomapvan/index_e.php">GSC - GeoMap Vancouver</a><br />
</li>
</ul>Malcolm V Lhttp://www.blogger.com/profile/00126268490488546890noreply@blogger.com4tag:blogger.com,1999:blog-2188731877707108811.post-8221329648010631132011-02-08T11:10:00.001-08:002011-03-02T21:44:47.177-08:00To study or not to study: a Metamorphic Genesis or a Dynamic Creek?Lately I've been thinking about what topic I should choose for doing my senior undergraduate major project. This project is essentially worth 3 credits, or one full course. The synopsis outlines it as almost a thesis but with a narrower scope of time, and only to be peer reviewed by my university professors. I'm planning on it for this semester next year, but want to utilize the coming summer months for field work.<br />
<br />
The first idea that comes to mind is to measure/analyze something local. I don't want to synthesize and regurgitate some phenomenon that is a world away where I can't put my hands on it (I do that enough on this blog). After all, one of the big reasons I chose geology is because on occasion the laboratory is the great outdoors. The second thing that comes to mind is that I want to break new ground. Not by finding new analytical methods or a stunning new hypothesis (I won't have the time, funds, knowledge nor experience to do that for several years), but by covering something in greater detail than has been.<br />
<br />
I might have access to basic hydrological equipment: current meter plus pH, conductivity, and DO probes. In that case I wish to study the fluvial geomorphology of a particular large creek that has not had a thoroughly holistic study. Plus my favorite geology book is <a href="http://www.amazon.com/Fluvial-Processes-Geomorphology-Luna-Leopold/dp/0486685888/ref=sr_1_2?ie=UTF8&qid=1297130937&sr=8-2">Leopold's</a>, and this would give me an excuse to read it again. Its geomorphology is of particular interest because the creek cut a channel down through glacial till and exposed a volcanic basalt layer underneath, thus a small portion of its mid-reaches has step-pool falls. More details found in the <a href="http://www.geocaching.com/seek/cache_details.aspx?guid=5f390726-77a9-4cbf-85c4-cf58e30d0f17">earthcache I created</a> for it.<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhVdT60vRAelnK84zu7vVnNUXR2j2pVkCh8ZiWVS_gRBW-Qyv_qA_rJTQ0a-eYn5pC-QlYvmAjpn7M3zOv9Zmv8EyQ-LG19r8_AHaG5lHAy780aZ9zjQC8vaVqHN1Kg2du-jJWe4fbrfkI/s1600/clifffalls.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="285" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhVdT60vRAelnK84zu7vVnNUXR2j2pVkCh8ZiWVS_gRBW-Qyv_qA_rJTQ0a-eYn5pC-QlYvmAjpn7M3zOv9Zmv8EyQ-LG19r8_AHaG5lHAy780aZ9zjQC8vaVqHN1Kg2du-jJWe4fbrfkI/s400/clifffalls.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Cliff falls in Maple Ridge, BC. Kanaka creek pinches <br />
here due to eroding down to a resistant lava flow</td></tr>
</tbody></table>If access to equipment or most of the drainage basin is not possible, I am considering doing a petrological study of a pre-Jurassic [mostly] metamorphic group on the north shore. There is surprisingly little information about it, beyond a few journal papers making slight references to it when describing other groups/formations that interact with it. This would involve a thorough investigation of approximately 8 sites of varying size (see map below) where outcrops have been identified, plus I'd get to use snazzy terms like <a href="http://www.encyclopedia.com/doc/1O13-contactaureole.html">aureoles</a> and metamorphic facies. All I'd need in that case is a rockhammer, a handlens, maybe a petrographic microscope.<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEheY9bGu24l9QP8mRzo96Hd282CU1ZfkLckUxPKJhQ0e7ofsL1fVcr45ZIhzLgQBKhyphenhyphenf-dPgV_cSFYwXVZIygrSzsnvogIm-T0vIETJmikO6LzYWX8aSIUaBhImEdPTtA9rKcXfrwQACKE/s1600/twinsmap.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="255" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEheY9bGu24l9QP8mRzo96Hd282CU1ZfkLckUxPKJhQ0e7ofsL1fVcr45ZIhzLgQBKhyphenhyphenf-dPgV_cSFYwXVZIygrSzsnvogIm-T0vIETJmikO6LzYWX8aSIUaBhImEdPTtA9rKcXfrwQACKE/s400/twinsmap.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Surficial geology map of North & West Vancouver<br />
#1 is the Twin Islands Group I'm considering for study</td></tr>
</tbody></table>I'll likely put this on the back burner until late spring, when I will have time to investigate the creek and gauge how I can approach it from various access points. In the meantime, professorial advice and anecdotes will likely sway me towards one or the other.<br />
<br />
<br />
<span style="font-size: x-small;">Terminology note: It took me a while to wrap my head around the phenomenon of roof pendants. Sometimes a blatantly obvious mechanism or concept eludes me, until a light bulb goes on. This has happened with things like pedimentation, cyclothems, Benioff zone. My best attempt to explain to myself the idea of roof pendants - When a batholith forms below overlying strata, it penetrates upwards, and thus makes contact with those layers. The layers will likely undergo contact metamorphism, and metamorphose under high temperature & low-moderate pressure. Erosion of subsequent material leaves the META members as isolated crops dangling/resting above the batholith. Essentially roof pendants have a parent rock, and are akin to xenoliths on a large scale but did not get included into the igneous mass, simply resting above it instead.</span><br />
<br />
Additional Info: <br />
<ul><li><a href="http://www.sciencedirect.com.ezproxy.kwantlen.ca:2080/science?_ob=ArticleURL&_udi=B6V93-47K2WK0-2&_user=1898427&_coverDate=09%2F05%2F2003&_alid=1633573416&_rdoc=1&_fmt=high&_orig=search&_origin=search&_zone=rslt_list_item&_cdi=5887&_sort=r&_st=13&_docanchor=&view=c&_ct=1&_acct=C000055247&_version=1&_urlVersion=0&_userid=1898427&md5=dc21da88fc48a62fceb9f8f214a516c5&searchtype=a">Landslide inventory in a rugged forested watershed: a comparison between air-photo and field survey data</a></li>
<li><a href="http://www.scribd.com/A-Geological-Excursion-Across-the-Canadian-Cordillera-Near-49-N-Highways-1-and-3-From-Vancouver-to-Southwestern-Alberta-and-on-to-Calgary-Alberta-/d/12393107">A Geological Excursion Across the Canadian Cordillera Near 49° N </a></li>
<li><a href="http://apps1.gdr.nrcan.gc.ca/mirage/full_result_e.php?id=108023">Geology Vancouver North, British Columbia</a></li>
<li><a href="http://www.geocaching.com/seek/cache_details.aspx?guid=5f390726-77a9-4cbf-85c4-cf58e30d0f17">Kanaka Creek earthcache</a> </li>
</ul>Malcolm V Lhttp://www.blogger.com/profile/00126268490488546890noreply@blogger.com1tag:blogger.com,1999:blog-2188731877707108811.post-33259260121112469612011-02-03T10:50:00.000-08:002011-02-03T10:50:27.145-08:00Field Photo TryoutIt's inevitable that a geo-geek will want to show off their collection of field photos. They generally show rocks, structures, facies, principles etc... tells a story and is a lot more interesting than showing a box filled with collected rocks & minerals, which in my opinion is tedious through the internet.<br />
<br />
Thinking about how to present them, I'm stuck between two methods I've seen other bloggers use: show a photo and give a complete explanation of what/when/where/how, or allow readers a shot at figuring out the what & how of the elements in the photo, and filling them in on the rest later on. So as a tryout, I will initially go with my preference, which is the latter. Below are two field photo's I've taken in southern British Columbia: <br />
<div style="text-align: center;"><br />
Field Photo #1 (height of photo =10m)</div><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh9QhLqVQcdGfgrkuOsv6sux5tZzX42ZPJY4mPwq0NptmLhuotb2H9fksYfn7mFBHiyDh371LPgqeaLfULixtxR1yIm9M8B3rN_0OhbCr0i6JEBo5O3NUS-14HaKotVj2Hha3KJL6mfV7A/s1600/mamquam.png" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="222" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh9QhLqVQcdGfgrkuOsv6sux5tZzX42ZPJY4mPwq0NptmLhuotb2H9fksYfn7mFBHiyDh371LPgqeaLfULixtxR1yIm9M8B3rN_0OhbCr0i6JEBo5O3NUS-14HaKotVj2Hha3KJL6mfV7A/s400/mamquam.png" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">What do you see here? (hint: two distinct depositional environments are shown)</td><td class="tr-caption" style="text-align: center;"></td><td class="tr-caption" style="text-align: center;"></td><td class="tr-caption" style="text-align: center;"><br />
</td><td class="tr-caption" style="text-align: center;"><br />
</td></tr>
</tbody></table><div class="separator" style="clear: both; text-align: center;"></div><div style="text-align: center;">Field Photo #2 (GPS = 15cm tall)</div><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgf3Pxeaj2iqpDdBXXTuElMjc7qrXy_j8T0aGG_aOrVe3ttw5lNOg46Vavj2UqtJ3qmSQ0A8ljtuOOZHIoTPZJ7kKJ2NvSANZJWXojnWtA8NSKJBG92JHGGTAozjL5AfUr3jKxk-Nz1Byo/s1600/Picture+002.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="316" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgf3Pxeaj2iqpDdBXXTuElMjc7qrXy_j8T0aGG_aOrVe3ttw5lNOg46Vavj2UqtJ3qmSQ0A8ljtuOOZHIoTPZJ7kKJ2NvSANZJWXojnWtA8NSKJBG92JHGGTAozjL5AfUr3jKxk-Nz1Byo/s400/Picture+002.jpg" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">What do you see here? (hint: mechanism at work on both rocks)</td></tr>
</tbody></table><div style="text-align: left;">Dunno if this format will work or not. Heck, I don't know if I have enough readers yet. But those who do read, feel free to take a stab (or rockhammer) at it in the comments. I'll follow-up later on depending on response, and change method if preferred.</div>Malcolm V Lhttp://www.blogger.com/profile/00126268490488546890noreply@blogger.com1