Biotite schist
Gneiss, schist & quartzite. Paleoproterozoic, about 2,500 to 1,600 million years old. 32 crags on this site have their map point on it.
What the map says
Conspicuously banded rock marked by alternating layers of contrasting composition; dark-gray to black, medium- to coarse-grained layers are rich in biotite, sillimanite, and magnetite; light- to medium-gray or bluish-gray, fine-grained layers contain more quartz and feldspar than biotite; white, coarse-grained layers consist of quartz and feldspar and minor biotite. Weathers to mottled reddish or yellowish brown. Layering is typically folded into moderate warps and tight flexures and isoclines. Protolith consisted of alternating beds of shale, siltstone, and sandstone. Regional metamorphism at about 1,700 Ma (Peterman and others, 1968, p. 2284) produced characteristic mineral assemblages that vary across the region depending on maximum local temperature and pressure. Northeast of the North Fork Big Thompson River, maximum temperature of metamorphism was as low as 525 degrees C (J.W. Drexler, oral commun., 1986), partial melting was not initiated (migmatite is absent), and the typical prograde assemblage consists of quartz, plagioclase, lepidoblastic muscovite, biotite, staurolite, andalusite, and iron oxides. Throughout most of map area, peak temperatures probably exceeded 700 degrees C (Nesse, 1977, 1984), anatectic melting was widespread (migmatite is ubiquitous), and typical mineral assemblage contains quartz, plagioclase, microcline, sillimanite, biotite, +/- garnet, +/- cordierite, hercynite, and iron oxides. Presence of garnet (rare) and (or) cordierite depends on local bulk composition; prograde cordierite appears to have formed by reactions of the type: biotite + sillimanite = cordierite + anatectic melt. Mineral changes between the lower and higher temperature regions are shown by the red dashed-line boundaries: sillimanite is present west of the S boundary, whereas staurolite and andalusite disappear near this boundary; microcline appears and lepidoblastic muscovite disappears at the K boundary; migmatite appears south and west of the M boundary; cordierite is present south and east of an unmapped, broad zone that extends from Eagle Rock (north of Estes Park) through Beaver Meadows, Mount Wuh, Ptarmigan Mountain, and southwestward to the east end of Granby Reservoir. GRI Source Map ID 141 (I-1973). ** Areas where numerous sills, dikes, or irregular bodies of Silver Plume Granite (Ysp) intrude biotite schist (Xs) [indicated by stippled regions on source paper map]. Areas that contain numerous conformable layers of pegmatite (YXp) [indicated by crossed regions on source paper map]. Lithology: metamorphic.
1:100,000 sheet: National Park Service Geologic Resources Evaluation program, 2006, National Park Service (32 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.
Alpine Rock
- Otis Peak19 routes · RMNP - Rock · 12,453 ft · granite (Silver Plume Granite) (another source)
- Cathedral Wall14 routes · RMNP - Rock · 10,833 ft · granite (Silver Plume Granite) (another source)
- Notchtop11 routes · RMNP - Rock · 12,087 ft · granite (Silver Plume Granite) (another source)
- The Seldom Seen Wall6 routes · RMNP - Rock · 12,202 ft · granite (Silver Plume Granite) (another source)
- Sharkstooth6 routes · RMNP - Rock · 12,327 ft · granite (Silver Plume Granite) (another source)
- Taylor Peak6 routes · RMNP - Rock · 12,837 ft · granite (Silver Plume Granite) (another source)
- Hayden Spires5 routes · RMNP - Rock · 8,516 ft · granite (Silver Plume Granite) (another source)
- Little Matterhorn5 routes · RMNP - Rock · 8,516 ft · granite (Silver Plume Granite) (another source)
- The Saber5 routes · RMNP - Rock · 11,849 ft · granite (Silver Plume Granite) (another source)
- Ypsilon Mountain5 routes · RMNP - Rock · 13,478 ft · granite (Silver Plume Granite) (another source)
- Petit Grepon4 routes · RMNP - Rock · 11,680 ft · granite (Silver Plume Granite) (another source)
- Pilot Mtn.3 routes · RMNP - Rock · 11,708 ft · granite (Silver Plume Granite) (another source)
- Haimovi Tower2 routes · Indian Peaks · 12,389 ft
- The Foil2 routes · RMNP - Rock · 8,516 ft · granite (Silver Plume Granite) (another source)
- Ptarmigan Towers2 routes · RMNP - Rock · 8,516 ft · granite (Silver Plume Granite) (another source)
- The Stiletto2 routes · RMNP - Rock · 8,516 ft · granite (Silver Plume Granite) (another source)
- Elk Tooth1 route · Indian Peaks · 12,707 ft
- Ogalalla Peak1 route · Indian Peaks · 12,911 ft
- Alberta Falls Wall1 route · RMNP - Rock · 8,516 ft · granite (Silver Plume Granite) (another source)
- Flattop Mountain1 route · RMNP - Rock · 8,516 ft · granite (Silver Plume Granite) (another source)
- The Gable1 route · RMNP - Rock · 8,516 ft · granite (Silver Plume Granite) (another source)
- The Penknife1 route · RMNP - Rock · 12,029 ft · granite (Silver Plume Granite) (another source)
- Snowdrift Buttress1 route · RMNP - Rock · 8,516 ft · granite (Silver Plume Granite) (another source)
- Thumb Rock1 route · RMNP - Rock · 8,516 ft · granite (Silver Plume Granite) (another source)
Estes Park Valley
- The Crags125 routes · CO Hwy 7 & Tributaries · 10,015 ft · granite (Silver Plume Granite) (another source)
- Lily Mountain36 routes · CO Hwy 7 & Tributaries · 8,877 ft · granite (Silver Plume Granite) (another source)
- River Wall8 routes and 1 boulder problem · Performance Climbing Park · 7,569 ft
- Deer Mountain South Side3 routes · Deer Mountain · 9,500 ft
- Pierson Mountain2 routes · CO Hwy 7 & Tributaries · 9,483 ft · granite (Silver Plume Granite) (another source)
- Best Summer Ever! Boulder1 boulder problem · 7,790 ft