The blue/grey dirt in the picture is the Tropic Shale. This picture was taken on a fault so you can see that the layers are tilted up a bit. The brown layer under the tropic is the Dakoda Sandstone. That layer represents the incoming beach from the inland sea as it came over the land then as it got deeper you get the tropic, the blue/greys, and finally more sandstone as it went back out which is the Straight Cliffs Formation.
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