• Double O Arch

    Arches

    National Park Utah

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  • Safety in Bear Country

    Black bears have been seen near Devils Garden Campground. Don't lure or feed them. Dispose of trash in designated receptacles; don't leave it in bags or other soft containers. Store food in vehicles or hard containers when not being prepared or consumed. More »

Rock Strata

This sequence shows the rock layers from youngest (top) to oldest (bottom). For clarity, some layers have been included that are not found within the park, but are visible from locations near the park boundary, such as the visitor center. The most dominant rock layers at Arches are the Navajo Sandstone through the Slick Rock Member of the Entrada.

Name of Rock Stratum

Geologic
Period

Millions of
Years Ago

Abajo, Henrys and La Sal Mountains

Tertiary

1.6 to 66

Mancos Shale

Cretaceous

66

to 144

Dakota Sandstone

Cedar Mountain Formation

Morrison Formation, Brushy Basin Member

Jurassic

144

to

208

Morrison Formation, Salt Wash Member

Morrison Formation, Tidwell Member

Curtis Formation, Moab Member

Entrada Sandstone, Slick Rock Member

Carmel Formation, Dewey Bridge Member

Navajo Sandstone

Kayenta Formation

Wingate Sandstone

Chinle Formation

Triassic

208

to

245

Moenkopi Formation

Cutler Group, Undivided

Permian

245 to 286

Honaker Trail Formation

Pennsylvanian

286

to

320

Paradox Formation

Did You Know?

Pinyon Pine

Pinyon trees do not produce pine nuts every year. These delicious nuts can only be harvested every three to seven years. This irregular schedule prevents animals from adapting to an abundance of pine nuts and guarantees that at least some nuts will become new trees instead of a quick meal.