Morrison Formation and Ralston Creek Formation, undivided
Jurassic, about 174 to 145 million years old. 1 crag on this site has its map point on it.
The map groups these named formations into this unit: Morrison Formation, Ralston Creek Formation.
What the map says
Ralston Creek Formation is purplish-gray sandstone and siltstone, underlain by grayishyellow silty sandstone containing clayey limestone and shale beds with red jasper. Thin layers of purple and white sandstone near base. Contains gypsiferous shale and white gypsum as thick as 8 m south of Turkey Creek (Bryant and others, 1973). Crops out only in Denver Basin. Thickness of Ralston Creek about 27 m in Morrison 7.5-minute quadrangle (Scott, 1972), but thins to the north, where it is about 10 m thick in Eldorado Springs quadrangle (Wells, 1967). Not mapped separately. Not recognized in either Blue River valley or Fraser basin
1:100,000 sheet: Kellogg and others, 2008, USGS Geologic Investigations Series 3000 (1 crag). 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.