Friday Field Foto #27: Cretaceous marine shale
I was browsing my collection of photographs this morning looking for a Friday Field Foto and, as happens when you start looking at old photos, I was reminded of when we were doing this field work. Today’s photo is from the Cretaceous of central Utah (the Book Cliffs). When I was working on my master’s in Colorado we took many field trips in the western Colorado and east-central Utah. I’ve shown some photos from the Book Cliffs before (here, here, and here).
What’s obvious in the photo is the cliff-forming sandstone unit capping the mesa. These strata represent the movement of the ancient shoreline through the area. The underlying thick shale sequence (the drab, slope-forming gray ‘rocks’) are offshore marine deposits. If you look closely (click on the image to get a better view), you’ll notice a darker gray path heading up the gray slope to the base of the sandstone cliff. Me and another guy measured a stratigraphic section and took some samples up that hill. We were out here helping out another student and this was supplemental data for him….he was trying to look at the nature of the marine shale over a thick sequence.
This falls into the category of “hey, whatever happened to those data?”
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Clastic Detritus 
You know, I drove past that area just yesterday afternoon.
I drive on the Mancos Shale a lot. Long, straight, open roads, places that feel like they should be great to drive fast… but which aren’t, because the $#&@#^ swelling clays make the roads so irregular.
I’ll try to download my own field photos and put something up this weekend.
aahh…the old Mancos gumbo…good times. Hope you guys had a burger at Ray’s.
So it is not just river runners but also geologists that frequent Ray’s? But then why aren’t there any pictures of geologists on the walls?
Man-cos!
kdinger…there may not be pics of geologists on the walls at Rays, but I can almost guarantee there are some in the restaurant every weekend in Aug-Sept.
chris…thanks for the tip, I will try that