NPS Photo by Tom Lyttle
The Lewis Shale is an olive-gray marine shale thinly interbedded with claystone, siltstone and sandstone as well as scattered beds of limestone. It overlies the Cliff House Sandstone and is exposed only near the northern boundary of the park. This unit was deposited at water depths greater than the Cliff House Sandstone and represents the last significant transgression of the Western Interior Seaway into northwestern New Mexico. Few fossils have been found in the Lewis Shale unit within the park.
Did You Know?
The Hopi place name for Chaco Canyon is Yupkoyvi, "the place beyond the horizon." Ten clans of the Hopi consider Chaco Canyon part of their ancestral homeland More...