| Hermit Formation | |
|---|---|
| Stratigraphic range: Permian, Early Leonardian[1][2] | |
.jpg) (Isis Temple, central Grand Canyon) The 3 top geologic units visible: 3)-(white-cliffs-prominence)-Coconino Sandstone, 2)-(slope-forming-Deep brnsh-red)-Hermit Formation, 1)-(red-uppermost-vertical-cliff & resistant)-Esplanade Sandstone (top unit of 4–member Supai Group) (Note: Distinctive Redwall Limestone upper horizontal-platform.) | |
| Type | Geological formation |
| Underlies | Coconino Sandstone |
| Overlies | Supai Group |
| Thickness | 900 feet (270 m), at maximum |
| Lithology | |
| Primary | siltstone and mudstone |
| Other | sandstone |
| Location | |
| Region |  Arizona-(North & Central Arizona)  California-(southeast) and  Utah-(southern) |
| Country |  United States-(Southwestern United States) |
| Type section | |
| Named for | Hermit basin, Coconino County, Arizona[3] |
| Named by | Noble (1923)[3] |
The Permian Hermit Formation, also known as the Hermit Shale, is a nonresistant unit that is composed of slope-forming reddish brown siltstone, mudstone, and very fine-grained sandstone. Within the Grand Canyon region, the upper part of the Hermit Formation contains red and white, massive, calcareous sandstone and siltstone beds that exhibit low-angle cross-bedding. Beds of dark red crumbly siltstone fill shallow paleochannels that are quite common in this formation. The siltstone beds often contain poorly preserved plant fossils. The Hermit Formation varies in thickness from about 100 feet (30 m) in the eastern part of the Grand Canyon region to about 900 feet (270 m) in the region of Toroweap and Shivwits Plateaus. In the Sedona, Arizona area, it averages 300 feet (91 m) in thickness. The upper contact of the Hermit Formation is typically sharp and lacks gradation of any kind. The lower contact is a disconformity characterized by a significant amount of erosional relief, including paleovalleys as much as 60 feet (18 m) deep.[1]