Sisters Rock
1 route · Boulder Creek granodiorite · 8,459 ft
How well located
Crag only 1
No route here has its own point yet. The map pin is the crag. At the wall? Survey it: 30 seconds per route.
Rock, from the geologic map
Boulder Creek granodiorite. Paleoproterozoic, about 2,500 to 1,600 million years old.
Gray, coarse-grained, equigranular to porphyritic, massive to weakly foliated biotite±hornblende±muscovite monzogranite, granodiorite, and tonalite. Forms large intrusive body (Boulder Creek batholith) west of Boulder (Gable, 1980). Typically weathers into grayish-tan rounded outcrops. Mean U-Pb zircon date from numerous analyses is 1,716±3 Ma (W.R. Premo and K.S. Kellogg, unpub. data, 2007), which supports earlier U-Pb zircon dates of 1,725 Ma (Stern and others, 1971) and 1,721±15 Ma (Premo and Fanning, 2000)
This is the map unit under this crag's map point, read from the 1:100,000 sheet (Kellogg and others, 2008, USGS Geologic Investigations Series 3000). The point can be a few hundred metres from the rock, a cliff often stands on the line between two units, and at that scale a line on the map is about 100 m wide on the ground, so the wall itself may be the neighbouring unit. Every crag on this unit: Boulder Creek granodiorite. Geology data: Macrostrat (CC BY 4.0), serving USGS and Colorado Geological Survey maps.
On the map since 1899
The USGS has mapped this ground since 1899. 25 historical sheets cover this crag's map point; the oldest is below.
USGS Historical Topographic Map Collection · Public domain · the record · placed by its coordinates
Report this item
Hidden as soon as you tell us, everywhere it appears, before anyone reviews it.
Public domain, U.S. Geological Survey. The sheet shows the ground as the survey found it then, which is why a trail or road you know may be missing. Every sheet over this point, 1899 to 1983: USGS topoView.
Routes
Photos from climbers
No photos here yet. If you're at the crag, yours would be the first.
Taken at the crag by climbers and published as they sent them. Each one's own location had to be within 0.5 km of this crag before we accepted it. See something that shouldn't be here? Use Report this photo under it and it's hidden at once. Anything else, write to us.
Conditions reported
Nothing reported recently.
Report what you see
Reports are dated and fade on their own: wet rock after 3 days, a bad bolt after a year. No names, no text.
Access & safety
The map point for this crag is on land managed by Roosevelt National Forest (federal). It lies inside national forest.
Land manager from USGS PAD-US (public domain), read 2026-09-29. It is the manager of the crag's map point, which can be a long way from the wall. What you may do on the rock is the manager's to say, not ours.
Rules for all Arapaho and Roosevelt National Forests land
- Fees
- No entrance fee for the forest. Some locations require a reservation, pass, permit or day-use fee.
- Overnight
- Camping more than 14 days in a 30-day period, or more than 30 days in a 365-day period, is prohibited across the forests and the Pawnee National Grassland. Dispersed camping is within 300 feet of most Forest Service roads, on National Forest land; the MVUM shows which.
Read on Arapaho and Roosevelt National Forests's own pages, checked 2026-09-29 by John Crawford. What they require, in full, or their own climbing page. These apply to the manager's whole holding; anything specific to this crag is above.
Nearby, from OpenStreetMap
- Toilets
- 1,394 m away (map)
- Campsite
- Unnamed, 712 m away (map)
Distances are a straight line from this crag's map point, which can itself be hundreds of metres off; a road may be much longer. Mapped by OpenStreetMap contributors (ODbL), so a toilet missing here may simply be unmapped. Parking here is what OSM has drawn nearby, not a guidebook's directions.
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