Walnut Canyon National Monument

After we visited Meteor Crater yesterday, we went to Walnut Canyon National Monument near Flagstaff. At first all I saw as I walked the 270 steps down to the Island Trail from the visitor center were the rock layers. I noticed right away the cross bedding within the CoconinoSandstone (left) and the blocky pattern of the Kaibab Limestone that was above it. After looking more, I noticed ancient dwellings of the Sinagua built into one layer of the overhanging limestone cliffs.

In the canyon you see the layering of the Kaibab Limestone on top of the Coconino Sandstone but what you don't see right away is a limey shale layer under the limestone. Because shale is less resistant to weathering and erosion, it was carved away by flowing water, leaving the limestone overhang above it. The Sinagua built walls and fronts using the overhangs as roofs. They used blocks of limestone cemented with clay. The dwellings go back at least 10 feet and are on average 5 feet high.

The Sinagua lived in the canyon from 1125 to 1250 when the canyon was fertile. It is not clear why the people left but they moved to new villages and were eventually assimilated into the Hopi culture.