About 800 years ago, the Northern Sinagua people built their cliff dwellings and pit houses in the walls of Walnut Canyon, in shallow alcoves of fairly soft sandstone tucked beneath harder, more resistant ledges of limestone. The geology gave them shelter — and the same sandstone is an important regional aquifer.
Walnut Canyon: layered marine limestone above cross-bedded, windblown (aeolian) sandstone. From the National Park Service Geologic Resources Inventory.
The monument
| Location | 16 km (10 mi) from downtown Flagstaff, Coconino County, Arizona |
| Authorized | November 30, 1915 |
| Area | nearly 1,428 ha (3,529 acres) |
| Protects | a dense concentration of well-preserved Northern Sinagua cliff dwellings, pit houses and other cultural sites |
The cliff dwellings are in the upper third of the canyon, which is named for the Arizona walnut trees that grow along its floor. The dwellings and the canyon's rich biological communities are of traditional cultural importance to many American Indian tribes of the Southwest.
The rocks
Walnut Creek has cut down through nearly horizontal layers of Paleozoic limestone and sandstone. The canyon averages 402 m (1,320 ft) from rim to rim and is deepest, 122 m (400 ft), at its western, upstream boundary.
| Layer | Where | What it is |
|---|---|---|
| Kaibab Formation (Permian) | upper walls and rim | resistant gray limestone |
| Toroweap Formation | beneath the Kaibab | light tan, cross-bedded sandstone |
| Coconino Sandstone | lowest exposed | light tan, cross-bedded sandstone; shelter for the Sinagua and a key regional aquifer |
Part of the geologic map of Walnut Canyon National Monument. Credit: National Park Service, Geologic Resources Inventory.
Where the detail lives
Walnut Canyon belongs to the Colorado Plateaus physiographic province and shares its geologic history with a region far beyond the monument. The NPS Geodiversity Atlas, drawn from the Geologic Resources Inventory, covers the full variety of a park's rocks, sediments, fossils, landforms, soils and the processes that shape them. The inventory produces geologic maps and reports for more than 270 natural resource parks, and a Soil Resources Inventory has been completed for Walnut Canyon; both are in the NPS DataStore.
Sources
Based on "NPS Geodiversity Atlas—Walnut Canyon National Monument, Arizona," National Park Service, a work of the United States government in the public domain. It cites Graham (2008).
Licence: CC0 1.0 (public domain) · Adapted from www.nps.gov
1
0
0
0
Comments
