Sheep Rock Unit

 
Sheep Rock is an outcropping - not quite a hill but not quite a mountain. It is vaguely pyramid shaped, with a basalt capstone and blue-green and pink sedimentary layers below.
Sheep Rock is named after the bighorn sheep that once populated its slopes.

NPS Photo by Tim Gohrke, 2018 Artist-in-Residence

Colorful Strata

The Sheep Rock Unit contains an amalgam of colorful strata and complex geology. From Cretaceous conglomerates to the flood basalts, the geologic features in this portion of the monument are a spectacle to behold.The predominant exposures of green rock seen on Sheep Rock are a multitude of reworked layers of volcanic ash. The rich green color of the claystone was caused by chemical weathering of a mineral called celadonite. This happened millions of years ago as water moved through the alkaline ash beds under high pressure.

 

Fossil Layers of the Sheep Rock Unit

 
 

Other Places to Visit in the Monument

 

Last updated: September 21, 2025

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Kimberly, OR 97848

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