Brushy Basin Shale Member of the Morrison Formation
Late Jurassic, about 153 to 145 million years old. 13 crags on this site have their map point on it.
What the map says
Gray, pale-green, red, and light-purple mudstone and siltstone, a few lenses of gray sandstone, limestone, and conglomerate. Thickness 200-300 ft. Lithology: clastic; shale; siltstone.
1:100,000 sheet: Day and others, 1999, U.S. Geological Survey Open-File Report 99-0427 (13 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.
Grand Junction Area
- Riggs' Hill Central49 boulder problems · Riggs' Hill · 4,824 ft
- Riggs' Hill East46 boulder problems · Riggs' Hill · 4,725 ft
- Main Area42 boulder problems · Dynamite Shacks · 4,732 ft
- Riggs' Hill West1 route and 19 boulder problems · Riggs' Hill · 4,889 ft
- Water Tower Hill17 boulder problems · South Camp · 4,786 ft
- Opal Hill16 boulder problems · McInnis Canyon Bouldering · 4,602 ft
- Escondido Circle12 boulder problems · Riggs' Hill · 4,722 ft
- El Chupacabra Area1 route and 10 boulder problems · Holy Cross Boulders · 5,052 ft
- Canyon Rim Drive9 boulder problems · South Camp · 4,866 ft
- Bentonite Mine7 boulder problems · Little Park Road · 5,742 ft
- The Arena5 boulder problems · Holy Cross Boulders · 5,066 ft
- Brooks Boulders3 boulder problems · Holy Cross Boulders · 5,077 ft
- The Other Side1 boulder problem · Dynamite Shacks · 4,693 ft