Rocks of Montezuma stock and vicinity, older felsic to intermediate porphyries of alkali-calcic group
Phanerozoic, about 100 to 56 million years old. 2 crags on this site have their map point on it.
What the map says
Large stocks, adjacent smaller bodies, and dikes in Nederland area and in southern Empire and northern Georgetown 7.5-minute quadrangles. Includes the Caribou, Bryan Mountain (also called Eldora), and Apex stocks. Includes monzogranite, monzogranite porphyry, biotite-hornblende±pyroxene monzogranite (Gable, 1969), and granodiorite (Ed Dewitt, written commun., 2007). K-Ar age of Caribou stock is 68.2±4.1 Ma on hornblende and 65.5±2.4 Ma on biotite (Marvin and others 1989). K-Ar age on Bryan Mountain stock is 60.6±1.8 Ma on biotite (McDowell, 1971; Marvin and others, 1974)
1:100,000 sheet: Kellogg and others, 2008, USGS Geologic Investigations Series 3000 (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.