an angular
unconformity exposed in the lower canyon wall along the Colorado River between Moab and Castle Valley (click to enlarge.) This stratigraphic structure is an easily recognizable surface of erosion that is preserved in the rock record, and in this case, occurs in the lowermost members of the Triassic-age Chinle Formation. It likely represents the upward movement of evaporites in the underlying Paradox Formation (Pennsylvanian) that resulted in the tilted beds which were ultimately eroded - the horizontal contact is the unconformity - after which sedimentary deposition continued.
The Wingate Sandstone (Jurassic) forms the escarpment and it is subsequently capped by a thin layer of the Kayenta Formation (also Jurassic.) Link to
stratigraphic column for the area around Arches National Park.
Stay tuned: fossilized crayfish burrows, ~ 220 million years in age, will be featured in a future post. Oh boy!
Did you bring your GigaPan? I'd love to see a GigaPan of this.
ReplyDeleteHey Ron: Yawp. Got it right here. I'll grab one in the next few days or later in the summer on a return trip. I'm contemplating a detailed one of an outstanding outcrop with crayfish burrow trace fossils (casts of burrows in 3D.) The GE100 is fun.
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