Castle Rock Conglomerate
Sandstone. Rupelian, about 30 to 29 million years old. 2 crags on this site have their map point on it.
What the map says
Indurated bouldery cobbly gravel composed mostly of Precambrian rocks exposed in the Front Range, but also contains some chert and Tertiary volcanic rocks. The sandy matrix of the conglomerate is well-cemented by silica, but basal part of deposits locally is less cemented and softer than the main part of the formation. Generally less than 15 m thick. In eastern part of mapped area includes mudstone, claystone, siltstone, and sandstone that contain volcanic ash.
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.