January 1, 2011

The Pawn's First Move

My first post on my new blog, and I guess introduction and purpose are in order. 
As a geography/geology undergraduate that has completed his first two years, I feel confident (enough) in my gathered knowledge coupled with a bit of experience with the tools of the trade to start expressing myself more in written form. I hope the blog will not only tune me more towards consistent writing on earth science subject matters and experiences, but also act as a kind of archive of interesting topics I have come across in course studies, field journeys, scholarly papers, publications, and other earth science activities.

Indeed I wish I could continue endlessly taking courses, perpetually learning knew things about every sphere of the earth system, but more and more I find that intermixed with studies is practical application, be it my GIS work for professors, or volunteer work for environmental agencies, or personal exploration of unique geological sites in my neck of the woods.

The Pumice Castle at Crater Lake ©Robert Mutch
What about the name? Really, it's because I had to choose something, and it had to be zippy. I have a distinctive interest in Oregon, as it is far enough from my home in BC to be exotic, but close enough to reach in a hard day of driving. The last time I was in the state, I explored central Oregon's semi-arid landscape, trekked around a shield volcano, walked on the lunar-like terrain of pyroclastic lava flows, gave myself a shock looking down a steep basalt canyon, and climbed up a mesa's fortress walls.

Pumice Castle itself is a result of its material toughness and foundation standing tall while deposits and lava flows around it eroded and fell into Crater Lake. Mazama is a composite volcano, its layers alternating between air fall deposits of ash/lapilli and lava flows of a basic to andestic/rhyolitic nature. One such layer of air fall was composed primarily of violently erupted pumice, that when deposited upon the flanks of Mazama was so hot that fragments welded together, and formed a lens roughly 50-60m thick. That pumice layer is underlain by a particularly dense andesite layer from a previous flow, thus providing a strong foundation for the lens to resist erosive forces. The eruption that eventually led to the pumice castle was itself not voluminous, but was fast and explosive in a shorter-than-average time period.

NPS diagram at the site
Thus after quieter activity prevailed (Crater Lake still has potentially active cinder cones, ie. Wizard island and other submerged ones), erosion overtook deposition, and as the edifice collapsed inwards, Pumice Castle remained standing as a protuberance that has itself eroded over time as the topography has reshaped.

I recommend Crater Lake as a definite on any North American geo-nut's bucket list, in particular the Rim drive and little side diversions to the Pinnacles (welded fumaroles), Phantom Ship (volcanic plug), Devil's Backbone (andesitic dyke) to name a few. If you're like me, music is your extra companion on fun drives, and my choice for central & south Oregon ended up being Pure Cult. There's nothing quite like driving through the desert scrub on a clear early autumn day whilst She Sells Sanctuary fills the ears.


4 comments:

Olelog said...

Nice to see a new geoblogger around. I wish you welcome and much success.

Ole

Michael said...

Welcome to the geoblogosphere! I've noted your arrival on my post for next week and will alert Geobulletin that there's a new blog on the block.

Suvrat Kher said...

Welcome and good luck!

jennipi said...

i second the beauty of crater lake! also, i'm excited to have found a new geoblog in it's early stages.