Al Rose Formation

The Al Rose Formation is a geologic formation located in Inyo County, California. It is notable for preserving fossils from the Cambrian Period, offering insights into early Paleozoic life and environments.^[4]

Al Rose Formation
Stratigraphic range: Ordovician
Type	Formation
Unit of	Mazourka Group[1]
Underlies	Badger Flat Limestone[1]
Lithology
Primary	siltstone, mudstone, and shale[2]
Other	chert[2]
Location
Region	Talc City Hills, California[3]
Country	United States
Type section
Named for	Al Rose Canyon, Inyo County, California[1]
Named by	Donald Clarence Ross[1]

Stratigraphy

The formation is primarily composed of shale, with interbedded limestone and sandstone layers, indicating a range of depositional environments. These rocks were deposited in a marine setting, as evidenced by their fossil content and sedimentary structures.^[5] The formation is stratigraphically positioned within the Great Basin region, an area renowned for its well-preserved Cambrian stratigraphy.^[6]

Fossil Content

Fossils recovered from the formation include a variety of trilobites, brachiopods, and archaeocyathids, providing critical data on the diversity of life during the Cambrian explosion.^[7] These fossils help paleontologists reconstruct ancient ecosystems and understand evolutionary dynamics during the Cambrian.

Regional Significance

The formation is a key part of the Cambrian stratigraphy in California. Its correlation with other Cambrian formations in the Great Basin, such as the Carrara Formation and the Bonanza King Formation, aids geologists in understanding the geological history of the region and broader paleoenvironmental changes.^[8]

See also

• Earth sciences portal
• California portal
• Paleontology portal

• List of fossiliferous stratigraphic units in California
• Paleontology in California