Green River Fm--Lower Part
Eocene, about 54 to 35 million years old. 1 crag on this site has its map point on it.
What the map says
Shale, sandstone, marlstone, and limestone in Anvil Points, Garden Gulch, and Douglas Creek Members; in Piceance basin Lithology: shale, sandstone, marlstone, minor limestone.
1:500,000 sheet: Horton and others, 2017, U.S. Geological Survey Data Series 1052 (1 crag). A contact line at that scale is about 500 m wide on the ground.
Served by Macrostrat (CC BY 4.0). The wording is the map's own, quoted as a fact about the mapped unit, not about any one wall.