Pegmatite
Granite. Proterozoic, about 2,500 to 1,000 million years old. 3 crags on this site have their map point on it.
What the map says
White, medium-grained to very coarse grained pegmatite with accessory biotite, muscovite, garnet, and (or) tourmaline. Pegmatites are widespread in the metamorphic rocks and likely formed during emplacement of both the Routt (approximately 1,690 to 1,725 Ma; Premo and others, 2010a) and Berthoud (approximately 1,350 to 1,440 Ma; DeWitt and others, 2010) Plutonic Suites; reliable field criteria for distinguishing pegmatite ages have not been established Lithology: pegmatite.
1:100,000 sheet: Workman and others, 2018, U.S. Geological Survey Scientific Investigations Map 3399 (3 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.