• South Window

    Arches

    National Park Utah

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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?

Close up of biological soil crust

The dirt is alive! A living crust called "Biological Soil Crust" covers much of Arches and the surrounding area. Composed of algae, lichens and bacteria, this crust provides a secure foundation for desert plants. Please stay on roads and trails to avoid trampling this important resource. More...