Monday, February 17, 2014

Keystone Thrust: Notes from my meandering

Some great geology views while traveling including this great view of the Keystone Thrust Fault.   

The older rocks of the layered limestone rocks of the gray Cambrian-age Bonanza Formation are overlying the buff to red sandstone of the younger Jurassic-age Aztec Formation. The older rocks were thrust up and over the younger rocks approximately 70 million years ago with an estimated crustal shortening of 60 miles.

There are plenty of thrust faults in Washington State, but not nearly so well exposed and easily seen. Amongst geologist this thrust fault is a famous location. Something to look for when you head into or out of Las Vegas, Nevada.

In my case I was just flying over the area. And, no, I was not on a get-a-way-from-winter trip. We had all of 1/2 hour in Phoenix between colder locations.

One other note as the great Southwest Drought has been in the news. Mount Charleston approximately 25 miles west northwest of Las Vegas had a very thin dusting of snow. Not good given that it was early February, and it took me a bit to convince myself I was indeed looking at Charleston. I have been on the 12,000-foot ridge of Charleston in late May and seen more snow.

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2 comments:

  1. GeezerhikerFebruary 18, 2014 at 11:19 AM

    Mount Charleston (12,000’) is about 25 miles west (OK, maybe WNW) of Vegas - are you sure this is the right peak?

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  2. Dan McShaneFebruary 18, 2014 at 1:23 PM

    Thanks for the elevation correction - should have remebered how thin the air was.
    And your right about the direction and distance. I was opperating purely from memory on this and remember driving north out of Vegas but then of course the road turn off is off to the southwest after not being very far north on the highway.
    I did double check the image with the aerial via USGS and am very confident it is Charleston.
    Corrections noted on the update of the post - thanks again.

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