Strata exposed on the White House Ruin Trail, Canyon de Chelly

Walking on the White House Ruin Trail in Canyon de Chelly National Monument (pronounced dah-Shay), observant visitors will notice a change in color and texture to the rocks underfoot. In this view, the upper part of the trail (top center) its cut into the Permian De Chelly Sandstone (right foreground), an orange-colored, cross-bedded, eolian sandstone deposited in a Sahara-like desert about 280 million years ago. The geologist is kneeling at the contact with the Triassic Shinarump Conglomerate Member of the Chinle Formation, a brown, coarse pebble conglomerate deposited in fluvial settings. (Disregard the rock and concrete trail construction below the geologist). Its age is about 225 million years, meaning g that the unconformity here represents about 55 million years of time. The contact is near vertical and the Shinarump fills an ancient slot canyon carved into the De Chelly Sandstone about 100 feet deep. (Photo by Wayne Ranney)