Deep Cut Guide

Lake Isabelle

1 boulder problem · granitic (Laramide intrusive rocks, with dioritic) · 10,843 ft

Take me there Routes ↓ Directions

Help locate these routes: survey the wall

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

Laramide intrusive rocks — granitic, dioritic. Phanerozoic, about 72 to 38 million years old.

Mainly intermediate to felsic compositions; some mafic

This is the map unit under this crag's map point, read from the 1:500,000 sheet (Horton and others, 2017, U.S. Geological Survey Data Series 1052). 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 500 m wide on the ground, so the wall itself may be the neighbouring unit. Every crag on this unit: Laramide intrusive rocks. Geology data: Macrostrat (CC BY 4.0), serving USGS and Colorado Geological Survey maps.

On the map since 1915

The USGS has mapped this ground since 1915. 28 historical sheets cover this crag's map point; the oldest is below.

Thumbnail of the 1915 USGS sheet covering Lake Isabelle
USGS 1:125000-scale Quadrangle for Longs Peak, CO 1915 · U.S. Geological Survey · 1915 · 1:125,000 sheet
USGS Historical Topographic Map Collection · Public domain · the record · placed by its coordinates
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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, 1915 to 1984: USGS topoView.

In print since 1877

  • 1877 Geologic Map of Colorado (Hayden), high-resolution scan · F. V. Hayden; scan by the Colorado Geological Survey · 1877

    The whole-state sheet of the 1877 atlas, scanned at full resolution by the state survey and free to download.

    Colorado Geological Survey (publication HM-01-04) · Public domain · read it

  • Geological and geographical atlas of Colorado and portions of adjacent territory · F. V. Hayden, U.S. Geological and Geographical Survey of the Territories · 1877

    The first geology anyone drew of this ground. Hayden's survey mapped the state in the 1870s; these are the sheets, with the rock units coloured as they understood them then.

    Internet Archive (Brigham Young University copy) · Public domain · read it

  • Mountaineering in Colorado: the peaks about Estes Park · Frederick H. Chapin · 1889

    The first book of Colorado climbing. Chapin's 1887-88 ascents of Longs Peak, Hallett, Ypsilon and the Mummy Range, with the approaches as they were before the park.

    Internet Archive (Harvard University copy, Appalachian Mountain Club, Boston) · Public domain · read it

  • Trail and Timberline, volume 2 (1918) · Colorado Mountain Club · 1918

    The Colorado Mountain Club's own magazine in its sixth year, with the club's outings and ascents as its members wrote them up at the time.

    Internet Archive (Brigham Young University copy) · Public domain · read it

  • Mountaineering in the Rocky Mountain National Park · Roger W. Toll, U.S. National Park Service · 1919

    The Park Service's own mountaineering guide, four years after the park was made. Peak by peak, with the routes of the day and the first recorded ascents Toll could find.

    National Park Service, scan at the Internet Archive (Brigham Young University copy) · Public domain · read it

Free to read: public domain or government work. About Alpine Rock as a whole, not this wall. More in the reading room.

From the archives

Photographs of this area held by the Library of Congress, oldest first. Every one carries the Library's own "no known restrictions on publication"; anything else is left out.

Arapahoe Glacier
Arapahoe Glacier · Tangen, Ed, 1873-1951 · 1921
Library of Congress, Prints & Photographs Division · Public domain · the record · indexed to this place by the archive
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Hidden as soon as you tell us, everywhere it appears, before anyone reviews it.

Arapahoe Glacier · Tangen, Ed, 1873-1951 · 1921
Library of Congress, Prints & Photographs Division · Public domain · the record · indexed to this place by the archive
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Hidden as soon as you tell us, everywhere it appears, before anyone reviews it.

Arapahoe Peaks and Glacier · Tangen, Ed, 1873-1951 · 1921
Library of Congress, Prints & Photographs Division · Public domain · the record · indexed to this place by the archive
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Hidden as soon as you tell us, everywhere it appears, before anyone reviews it.

Fair Glacier from rim of Hell Canyon, Col. · Tangen, Ed, 1873-1951 · 1921
Library of Congress, Prints & Photographs Division · Public domain · the record · indexed to this place by the archive
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Hidden as soon as you tell us, everywhere it appears, before anyone reviews it.

Routes

Also within 3 km

Straight line between the two crags' map points, each of which can be some way from its rock. For when this wall is full, or the sun has found it.

Photos from climbers

No photos here yet. If you're at the crag, yours would be the first.

Pick a photo from your camera roll rather than taking one here: a picture taken inside a browser usually has no location saved in it, and we check that the photo was taken at this crag before publishing it. Photos of guidebook pages and topos are refused — they're the author's work. By sending one you're letting us publish it.

Nobody reviews these before they appear, so anyone can report one and it's hidden straight away — including you, if you change your mind, and including a photographer who finds their own picture here.

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.

Sun today
sun 07:40-14:00
Wall faces SE (USGS elevation). Shade from the surrounding terrain is counted.
Deep terrain: the skyline averages 16° above horizontal, so the sun has to climb well clear of the rim before it reaches this wall.
Crags by sun and shade →
Rain & forecast
No recent weather for this crag.

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

Emergency: call 911. Read out your location: Works without signal. If GPS fails, this crag's approximate map point is 40.07026 N, 105.61175 W (Lake Isabelle). That point can be off by hundreds of metres, so say so.

The map point for this crag is on land managed by Roosevelt National Forest (federal). It lies inside wilderness area, 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

Campsite
Pawnee Campground, 3,896 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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