Sandy Mysteries in Dinosaur N.M., UT
A week ago I found myself cruising north to meet a friend in Dinosaur, UT- choosing this spot because, well- dinosaur hunting! Sadly, no living evidence of the saurischia or ornithschia variety greeted us, but we left satisfied after burning a coal seam in a laminar sandy shale formation (unknown name! if only I'd known of the Flyover Country or Rock'd App then...), marveling at Weber sandstone deformation in Echo Park, and generally enjoying the following...
...Split Mountain overlook from Desert Voices trail, Dinosaur National Monument, UT (September 2018)
Note red/tan mudstone beds tilting west. Photo taken from what I assume to be a Weber sandstone (?) hogback facing southeast.
The world, 260 Ma: depositional environment for Weber sandstone. Find Utah (it's north of South America, somewhere...). In those good old days 260 million years ago, we were equatorial, sandy and hot!
Trying to set this black seam in the Weber sandstone on fire - coal? Probably not...
Enjoying the company of contorted cross beds in the Weber Sandstone (?) of Echo Park, Dinosaur Natl Monument (not the Echo Park of Los Angeles!)
Sandstone slumping during deposition (2).
Can't go wrong with a stratigraphic record. Weber sandstone - Pennsylvanian...
(https://www.nps.gov/museum/exhibits/dino/column/column.html)
Can you believe the size of those ergs? I can't. I'd love to have zoomed down them on a sand board, though. Note the Paradox Basin (evaporite deposits) in the four corners region. Now covered by thousands feet sediments eroded from the Ancestral Rockies and the general surrounding sedimentary neighborhood, these salts mingle with oil deposits and outcrop at the surface! (Like the Onion Creek salt diapir just 14 miles NE of Moab).
http://www.science.earthjay.com/instruction/CR_eureka/2016_spring/GEO_02/lectures/lecture_14/?C=S;O=D
A possible explanation for the Weber sandstone slumping? "Penecontemporaneous hydroplastic flowage." One heck of a phrase for that old type writer.
Goodbye, friendly wash!
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Some scattered references for my use later on...
- Slump features, Field Geology Illustrated, Terry S. Maley, p. 323
Formations found around Split Mountain: http://pages.mtu.edu/~jeh/Syl.UT/Dinosaur.html Permian Weber Sandstone to Cretaceous Frontier Formation.
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