NPS Photo by Phil Varela This unit is composed of primarily marine sandstone interbedded with thin layers of shale and is similar in composition, fossil assemblages, and depositional environment to the Intermediate unit of the Cliff House Sandstone. This unit is the youngest unit in the park and overlies the Lewis Shale. The Pictured Cliffs Sandstone represents the final regression of the Western Interior Seaway from northwestern New Mexico. |
Last updated: February 24, 2015