Sunday, June 14, 2009
San Rafael Swell
First off it is Rafael. I spelled it Raphael in an earlier post and that is just wrong.
The San Rafael Swell is a desolate area of eroded beauty in central Utah. All of Utah could really be called an area of eroded beauty (though certainly not of eroded morals) but the Swell, pretty much smack in the middle of the state is exceptional.
Lets begin with geology. Simplistically land is made up of layers of sediment and then sometimes these layers are lifted up, or pushed down or cut through by water and wind. Though this is the case pretty much everywhere it is easiest to see out west since there is less of that pesky vegetation covering everything up.
Utah's layers (the layers of the Colorado plateau) were deposited successively by differing processes over the eons. At points Utah was the floor of a great sea and the sediments are those of shell and other calcium rich substances (limestone) other times it was the edge of the sea and there are layers of sand that has been compressed into cohesive strata (sandstone) and other times it might be hardened lava or volcanic ash. Tectonic forces pushed up the area known as the Colorado Plateau (which consists of parts of the four corners states, Arizona, Utah, Colorado, New Mexico) in a relatively uniform block (as opposed to being folded or subducted into mountains.) The San Rafael Swell is an uplift upon this uplift. Structurally you could think of it as many blankets layered over a trampoline (the blankets are the successive rock layers). Then forces pushed up on the bottom of the trampoline resulting in a layered dome structure.
Any time land is lifted up water that falls on that land will want to move down to lower elevations and when it does so it will erode the rock along with it. In the southwest the climate is usually very dry and when it does rain it tends to rain a lot and the soils, as dry as they are, cannot absorb any of this water and you end up with catastrophic floods that have even more erosive power. As such you get great gorges and canyons cut through the strata which are very scenic (National Parks on the Colorado Plateau include: Canyonlands, Arches, Capital Reef, Bryce Canyon, Zion and Grand Canyon)(I went on a road trip with my sister a few summers ago that included visits to all of these parks and by the time we were done I decided I was pretty cashed out on erosion and ready to see some volcanoes.)
The San Rafael Swell is so cut through and erratically eroded that it is quite difficult to travel across and, in fact, I-70 is the only paved road to cross it. Even then you have to wonder why since 70's western terminus is Cove Fort, Utah, which isn't much of a town. I suppose the reason would be to provide a link from the southwest (LA and Vegas on I-15) towards Denver, but still traveling 70 through Utah you have to think "this couldn't have been easy."
I-70 E following a canyon off of the swell.
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