Boulder

4,080 routes and 1,060 boulder problems at 257 crags. "Boulder" is the catalogue's own grouping — a town, a canyon or a corridor, whichever climbers actually say.

Which way a wall faces is known for 130 of these 257; the rest say nothing rather than guess. Sun and shade by season ranks the ones we know.

At a glance

Seasonal closures ahead: Boulder Canyon raptor closure (Eagle Rock, Blob Rock, Bitty Buttress) (02-01 to 07-31); Boulder Canyon raptor closure (Vampire Rock, Black Widow Slab) (03-01 to 07-31); Flatirons North falcon closures (Third Flatiron) (02-01 to 07-31); Flatirons Central falcon closures (The Box, Back Porch) (02-01 to 07-31); Flatirons South falcon closures (Fern Canyon, The Wings, Shadow Canyon) (02-01 to 07-31); Mickey Mouse Wall falcon closure (02-01 to 07-31); Bat roost closures (The Hand east face, Finger Flatiron standard route, Shark's Fin, Mallory Cave) (04-01 to 10-01); Der Zerkle east face bat closure (04-01 to 09-01) — closures.

Crags sit between 5,273 and 8,527 ft (elevation known for 257 of 257).
Rock, where known (244 of 257 crags): granite (138), sandstone (96), gneiss, schist & quartzite (10).
Mapped geology under these crags (257 of 257 read off the geologic map): granitic rocks of 1700-m.y. age group (79), fountain formation (76), boulder creek granodiorite (36) and 16 more units.
The USGS has mapped this ground since 1899; each crag page shows its oldest sheet.
206 crags within a walk of an RTD stop. Mapped toilets within 2 km of 143.
Sun and shade:

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
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

Free to read: public domain or government work, each opened and signed by a person. The whole shelf is in the reading room.

From the archives

Photographs of Boulder held by the Library of Congress, oldest first, each marked "no known restrictions on publication" by the Library. Shown from their servers, not copied here.

Boulder, Colorado · Detroit Photographic Co. · 1900 · photochrom
Library of Congress, Prints & Photographs Division · Public domain · the record · indexed to this place by the archive

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