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Author Topic: Is this an impact crater?  (Read 6330 times)

blakestyger

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Is this an impact crater?
« on: 19/03/2009 12:13:47 »
It doesn't look like one to me but I'm not a geologist. It's in Texas, I'd get its image but don't know how.
Does anyone know what it could be? Best viewed at about 23km.

Google Earth, 29o 26' 47.06" N and 103o 49' 15.8" W

Thanks


 

Offline JimBob

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Re: Is this an impact crater?
« Reply #1 on: 19/03/2009 16:39:40 »


No it is not an impact crater. It is a feature called "The Solitario"


It resulted from the emplacement of a large laccolith about 45-50 Million years ago. A laccolith is a mass of igneous rock formed from magma that did not find its way to the surface but spread laterally into a lenticular body, forcing overlying strata to bulge upward. The oldest rocks exposed are Cambrian and there is almost a full geologic column in the exposed surface rocks. Up until recently this was a private ranch but when the owner passed away he bequeathed the area to the state park system. A limited number of people can now get in to this area to see the rather spectacular geology exposed. I was in there as a student but have not been back since it became public.

You can see to the southeast the shield of the volcano in the center of Big Bend National Park. Other volcanic features, dikes, sills, flows - can be seen in the aerial photography on Google Earth. This area also has mercury mines. At Terlingua there has been a mercury mine sporadically since 1888. It is not being mined at present but the cinnabar deposits are rather widespread, if not massive. Cinnabar mines can be found as far away as the other side of the national park - 60 miles away. This part of West Texas and on north for a hundred miles is full of volcanics - strange volcanics, especially zeolites.

For more information on the Solitario see http://corry.ws/CorryBook-9.htm  This a detailed description of the Solitario originally publishes as a GSA Special Paper. (Geological Society of America)
 

blakestyger

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Re: Is this an impact crater?
« Reply #2 on: 19/03/2009 17:55:53 »
Thankyou JimBob - great to have such good geology at hand, most local geology here is glacial deposits.
Nice link too, especially the dream. I'm starting to run out of courses to do but they're offering geology next September - so I'll probably take it up.
 

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Re: Is this an impact crater?
« Reply #2 on: 19/03/2009 17:55:53 »

 

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