Tag Archives: Permian

A very bored Permian brachiopod

Mark Wilson November 15, 2009 11:29 am

COLLEGE STATION, TEXAS–I never get tired of that too-obvious joke. I found the above productid brachiopod on the last outcrop of our little Texas expedition. It has been drilled by barnacles, which leave a distinctive slit-shaped hole with a tiny … Continue reading →

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Two West Texas outcrops: which looks more inviting?

Mark Wilson November 15, 2009 11:27 am

COLLEGE STATION, TEXAS–The upper one is the base of the Valera Formation on US Highway 84 (N31.88196°, W99.47115°) and the lower one is the lower Bead Mountain Formation on Route 6 near Albany; both are Permian and both have delicious … Continue reading →

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The puzzle of gypsum

Mark Wilson November 15, 2009 11:25 am

Our Permian sections on this Texas trip have had thick beds of gypsum only a meter or three beneath our fossiliferous limestones and shales. Gypsum (calcium sulfate) is an evaporite mineral, indicating when the Permian shallow sea in this case … Continue reading →

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You’re never alone on an outcrop

Mark Wilson November 13, 2009 10:28 pm
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A West Texas outcrop

Mark Wilson November 13, 2009 10:18 pm

BROWNWOOD, TEXAS–It was nearly a five hour drive from College Station, Texas, through the Hill Country to our first Permian exposure in West Texas. (We passed, by the way, through Killeen and Fort Hood.) It was worth the trip for … Continue reading →

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