|Cathedral of the Sun|
Cathedral Valley presents another chapter in the story of Capitol Reef's geology. The geologic layers and eroded features here are different than those seen in other sections of the Waterpocket Fold. The Bentonite Hills among the Hartnet Road and the Painted Desert on the Cathedral (also known as the Cainville Wash) Road appear as softly-contoured, banded hills in varying hues of brown, red, purple, gray, and green. The hills are composed of the Brushy Basin shale member of the Morrison Formation. This layer was formed during Jurassic times when mud, silt, fine sand, and volcanic ash were deposited in swamps and lakes. Bentonite clay (altered volcanic ash) absorbs water and becomes very slick and gummy when wet, making vehicle or foot travel difficult or impossible.