| Lewis Shale | |
|---|---|
| Stratigraphic range: | |
 Lewis Shale in road cut in the type area, La Plata valley, Colorado | |
| Type | Formation |
| Sub-units | Dad Sandstone Member, Huerfanito Bentonite Bed, Teckla Sandstone Member. |
| Underlies | Pictured Cliffs Formation |
| Overlies | Mesaverde Group |
| Thickness | 600 m |
| Lithology | |
| Primary | Shale |
| Other | Sandstone |
| Location | |
| Coordinates | 37°12′54″N 108°00′22″W / 37.215°N 108.006°W |
| Region | Mountain states, United States |
| Country |  USA |
| Type section | |
| Named for | Fort Lewis (former Army installation in La Plata County, Colorado) |
| Named by | Charles Whitman Cross, A.C. Spencer, and C.W. Purington |
  Lewis Shale (the United States)  Lewis Shale (Colorado) | |
The Lewis Shale is a geologic formation in the Western United States. It preserves fossils dating back to the Campanian to Maastrichtian stages of the late Cretaceous period.