This piece of Moenkopi sandstone is perhaps 240 million years old. Pangea was in the process of assembling. Over the next forty million years the North American plate rafted up to form the western coast of the Pangaean landmass, astride the equator.

The Moenkopi Formation of deep red and brown-red was laid down in a broad stretch of coastal flat. It sloped gently down southwesterly toward southern Nevada, crossing several western states in the process. The sandstone was often laid down in gentle lagoons, preserving ripples, plants and occasionally the marks of claws dragging in the mud and sand. This is the early Triassic; life was beginning to rebound after the Permian extinction wiped out nearly all life on Earth. The first dinosaur fossils were preserved in this layer.

Moenkopi itself is a small Hopi town near Tuba City in central Arizona.