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.
Stratigraphic range: Permian, Early Leonardian 275–270 Ma
(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.)
|Thickness||900 feet (270 m), at maximum|
|Primary||siltstone and mudstone|
|Region||Northern Arizona, southeast California, southeast Nevada, and southern Utah|
|Country||United States of America|
|Named for||Hermit basin, Coconino County, Arizona|
|Named by||Noble (1923)|
|Wikimedia Commons has media related to Hermit Formation.|
- Blakey, RC (2003) Supai Group and Hermit Formation in: Beus, S.S., Morales, M., eds., pp. 136-162, Grand Canyon Geology, 2nd. Oxford University Press, New York.
- Anonymous (2006i) Hermit Formation. Stratigraphy of the Parks of the Colorado Plateau. U.S. Geological Survey, Reston, Virginia.
- Noble LF (1923) A section of the Paleozoic formations of the Grand Canyon at the Bass Trail. Shorter contributions to general geology, 1922: Professional Paper no. 131-B. U.S. Geological Survey, Washington DC, p. B23-B73.
- Blakey, Ron and Wayne Ranney, Ancient Landscapes of the Colorado Plateau, Grand Canyon Association (publisher), 2008, 176 pages, ISBN 978-1934656037
- Chronic, Halka. Roadside Geology of Arizona, Mountain Press Publishing Co., 1983, 23rd printing, pp. 229–232, ISBN 978-0-87842-147-3
- Lucchitta, Ivo, Hiking Arizona's Geology, 2001, Mountaineers's Books, ISBN 0-89886-730-4
- Mathis, A., and C. Bowman (2007) The Grand Age of Rocks: The Numeric Ages for Rocks Exposed within Grand Canyon, Grand Canyon National Park, Arizona, National Park Service, Grand Canyon National Park, Arizona.
- Shur, C., and D. Shur (2008) The Hermit Formation In Northern Arizona. Arizona Fossil Adventures.