Laramie Formation
Maastrichtian, about 72 to 69 million years old. 2 crags on this site have their map point on it.
What the map says
Shale, claystone, siltstone, and sandstone containing coal beds, mainly in the lower part. Thickness variable but as much as 230 m. Source of coal, brick clay, and refractory clay.
1:100,000 sheet: Trimble and others, 2003, U.S. Geological Survey Geologic Investigations Series I-856-H (2 crags). A contact line at that scale is about 100 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.