During the Tertiary period, the rivers in the region removed much of the basin fill exposing older bedrock.
The rocks in the Owl Creek Range date from the Mississippian age through the Cretaceous period.
In areas near the Boysen Fault, just north of Boysen Reservoir's dam at the southern mouth of Wind River Canyon, erosion has removed the upper part of the thrust of the mountain, exposing Cambrian and Ordovician rocks, overlaying Triassic age rocks.
[3] Wind River Canyon has several markers along the main roadway through it, which indicate the time period the rocks are from.
[4] Metavolcanic rocks of predominantly basaltic and dacitic composition have been found in the canyon.