Columbia Basin Trip: Day 3 - McCall and a bunch of Falls

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.

Info board @ Rowena Crest parking

But first, before the falls, it was time for a satisfying hike. Hiking Oregon's Geology guide book spoke of a 4-5 mile hike through a nature preserve just outside The Dalles (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 Mima Mounds, 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 lupines, balsamroot, 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.

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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 Missoula floods 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).

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 (Grande Ronde Basalt) 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.

"... 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. ..." [Norman and Roloff, 2004]

Latourell Falls from the lower gallery
Click for short video of falls in action

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.

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 (Osoyoos doesn't count). Ahh the possibilities...I just wish they wouldn't butt up against the lack of time & money.

Additional Info:

• Northwest Waterfall Survey - Latourell Falls
• Northwest Waterfall Survey - Multnomah Falls
• The Nature Conservancy - Tom McCall Preserve at Rowena
• Map of Oregon Waterfalls
• T.L. Barry et al - New 40Ar/39Ar dating of the Grande Ronde lavas: Implications for duration of flood basalt eruption episodes

Columbia Basin Trip: Day 2 - Sisters along the Columbia

Looping around the Wallula Gap 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.

Two distinct forms of basalt make up the Sisters

Every geoscience geek with the smallest bit of knowledge of Pacific Northwest geology knows of the Glacial Lake Missoula floods and their offspring, the Channeled Scablands. 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 Day 1, 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.

For those not familiar with the Scablands, their features & their origins: During the late Pleistocene, the Cordilleran ice sheet 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 Columbia River gorge. The last of the floods, called the Bretz flood, released 1600 km³ of water in a two-day period, inundating nearly the entire Channeled Scablands region, and even extended into the Willamette River valley south of Portland, before exiting into the Pacific near Astoria.

Diagram of geographical interaction between Pleistocene ice sheets (blue), Glacial Lake Missoula (yellow), and the full extent of the Channeled Scablands (orange)

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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...

Looking west on the Columbia River along I84, just outside of Rufus. Those are whitecaps, not rapids

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.


Additional Info:

• USGS - Columbia River Flood Basalts
• G. K. C. Clarke et al - Outburst floods from glacial Lake Missoula
• NOAA - Salt-wedge estuaries 
• Wind Energy Facilities in the Columbia River Gorge?

Columbia Basin Trip: Day 1 - a Lahar and an Anticline

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 Ellen Morris Bishop's Hiking Oregon's Geology 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.

After a few hours driving, the first stop was an aside from I90-East, to visit the roadcut that exposes the Ellensburg Formation 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 CRBG 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 Kittitas and Yakima counties.

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.

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)

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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 Yakima River canyon, called the Umtanum, 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.

Example of eroded/oxidized remnants of columnar Yakima Basalts

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.

Columnar, Hackly, Pillow, all visible on one face

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On my way out, a last pullover harkened to me, maybe because my GPSr kept bleeping at me that an earthcache 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.

Evolution of Yakima river course during folding

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 Washington State Parks and Recreation Commission.

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 Umatilla Plateau & Yakima Folds 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...

Additional Info:

• USGS Coordinate Info for Umtanum Ridge features
• David Alt - Glacial Lake Missoula and Its Humongous Floods
• J. D. MacDougall - Continental Flood Basalts (Petrology and Structural Geology)
• Floods, Faults, and Fire: Geological Field Trips in Washington State 

Learning from the gentry: Maars and Tuff Rings

Uni 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 course outline), 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 VEI 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 this course you only need to know...".

Diagram of the various zones and
facies of a maar-diatreme

So I've had to teach myself some ins and outs of volcanism to go beyond the basics. The Firefly guide 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 Jessica Ball, 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.

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 tuya's, 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:

• Vast majority of maar-diatreme volcanic features occur in silica-poor (basaltic) volcanic fields
• Tuff Rings/Cones are thought of as the phreatomagmatic equivalent of rhyodacitic lava domes
• Posteruption, diatremes develop unique stratification of different facies (tuff, volcaniclastics, breccias, sediments, xenoliths)
• Maar lakes are generally short lived, as sediment fills in the shallow depression. If one exists, it indicates a geologically recent phreatomagmatic eruption
• 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)
• 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
• The center of Maars and Tuff Rings can have a measurable gravity anomaly when compared to the surrounding country rock
• 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
• Diagenesis (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

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 Oregon's Lake county. Unfortunately, it was several years ago, prior to my budding interest in the geosciences. However, Fort Rock and Hole-in-the-Ground 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.

Hole-in-the-Ground maar (left) and Fort Rock tuff ring (right), both protected as Oregon state parks
43° 23.314'N 121° 7.919'W will place you smack between the two

Additional Info:

• Volker Lorenz - Maar-Diatreme Volcanoes, their Formation, and their Setting in Hard-rock or Soft-rock Environments
• Brennan T. Jordan - The Oregon High Lava Plains: Proof against a plume origin for Yellowstone?
• USGS - Maars and Tuff Cones
• J.D.L. White - Maar-diatreme volcanoes: A review
  

The Chief of a thousand

The 1000^th geocache is a milestone that calls for a significant effort to find a spectacular cache. I've never been up the Stawamus Chief's 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.

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 Mount Conner not far from Uluru). The caches themselves were easy to find, as the GPSr was on target all day long.

BC Parks info board explaining the Chief's physical geology

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.

This opening was also the first place to showcase the dominant process that is the hidden danger of the Chief trails → exfoliation. 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 Howe Sound, the ant-colony of Squamish, and the snowbound Mount Garibaldi complex. 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. 

Examples of exfoliation along Chief trail. Slab detachment on the left, jenga-like sheet fractures on the right

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.

Why is it every time I see this mountain I think of Babylon 5?

Additional Info:

• Stawamus Chief Provincial Park
• Peaked out! Stawamus Chief geocache
• The Chief: Pillar of Granite

Field photo Set #2

Late 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.

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 Mt. Mazama complex in what is today Crater Lake National Park.

The Pinnacles fumarole features, looking west.
The V-shape valley shows river erosion exposing them

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 (SO₂, CO₂, H₂S), 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 nuée ardente flowed down Mazama's east flank, carrying scoria. 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.

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 rhyodacite ash falls that preceeded the scoria-laden pyroclastic flow.

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This field photo is of a roadcut along the North Umpqua highway, not far from Watson Falls (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 km³), 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). Tephrochronology 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.

The white color stems from sanidine 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.

Additional Info:

• Mount Mazama and Crater Lake: Growth and Destruction of a Cascade Volcano
• Cascades Volcano Observatory - Mazama Ash
• Ellen Morris Bishop - Hiking Oregon's Geology
• Journal of Volcanology and Geothermal Research - Eruptive history of Mount Mazama and Crater Lake Caldera, Cascade Range, U.S.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 glance at Saskatchewan Potash mining

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.

Why is Saskatchewan so rich in potash? 

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 restricted inland sea. 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 evaporite beds. 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.

World potash reserves, top ten states (left); cross-section of Saskatchewan strata with sylvinite beds (right)

Types and uses of Potash

Potash occurs when Potassium binds with another compound or element to produce a salt. Such compounds include Potassium Chloride (KCl), Potassium Sulphate (K₂SO₄), Potassium Carbonate (K₂CO₃), and Potassium nitrate (KNO₃), 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.

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.

Click to read more...

Earth Story: The Beeb's forgotten geology gem

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 "Earth Story", an 8-parter released in the late 90's. 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 Banded Iron Formations and Stromatolites, and such events as the Rodinian Snowball Earth and ELE's. 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.

Naturally, I looked up the rest of the documentary on youtube, and lo and behold found a user's channel 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:


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.


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.


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.



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.

Above is just a small sample of the entire series. Thanks to Kurdistan Planetarium for supplying the videos online. Readers, enjoy!

Additional Info:

• University of Wisconsin @ Madison - Underneath the Mountains
• The Rules of Life - Welcome from Aubrey Manning
• Aubrey Manning discussion with Richard Dawkins