Biotite granite
Granite. Mesoproterozoic, about 1,600 to 1,000 million years old. 1 crag on this site has its map point on it.
What the map says
Gray to buff, fine- to medium-grained, equigranular to seriate porphyritic biotite syenogranite to monzogranite, correlated with granite of Log Cabin batholith and other Silver Plume-type granites throughout the Front Range (Eggler and Braddock, 1988; Shaver and others, 1988); associated with smaller unnamed intrusive bodies and dikes. Color index generally 2 to 5. To the north of the Log Cabin batholith, unit forms an oval, irregular plug intruded into the Sherman Granite phases of the Virginia Dale ring-dike complex; intrusion age established as 1,390±30 Ma (Rb-Sr isochron; recalculated from Peterman and others, 1968). To the south and east of the Log Cabin batholith, unit includes numerous irregular shaped intrusive bodies and dikes along the 1.2 Ga (Abbott, 1972) Skin Gulch shear zone which might be displaced or satellitic bodies of the main Log Cabin batholith or may be separate plugs and dikes intruded between the Log Cabin and Longs Peak-St. Vrain batholiths. Unit is primarily porphyritic to south where equigranular phase (Yge) is mapped separately; includes mafic quartz monzonite of Abbott (1976) Lithology: syenogranite, monzogranite, granite.
1:100,000 sheet: Workman and others, 2018, U.S. Geological Survey Scientific Investigations Map 3399 (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.