Wyman Formation

Wyman Formation
Stratigraphic range: Ediacaran PreꞒ Ꞓ O S D C P T J K Pg N [1]
Astragalus oophorus, growing on substrate within the Wyman Canyon, the locality after which the formation is named.
Type	Geological Formation
Underlies	Reed Dolomite
Thickness	9,000 ft (2,700 m)[1]
Lithology
Primary	Siltstone
Other	Carbonate, Phyllite, Claystone
Location
Region	California
Country	United States
Type section
Named for	Wyman Canyon

The Wyman Formation is an Ediacaran aged geologic formation in California, primarily within the Inyo Mountains.^[1]

Geology

The Wyman Formation is mainly composed of medium-gray, olive-gray or dark-greenish-gray phyllitic siltstone, which itself contains silt-size quartz particles, mixed in with fine textured biotite, chlorite and muscovite. Inter-laid within the siltstone are layers of laminated limestone or marble, up to 50 ft (15 m) thick in some places. Some of the limestone layers are oolitic or pisolitic, the pisolitic structures possibly being algal in origin, and contain limestone pellets. Occasional dolomite layers can also be found, but may have been a result of the limestone being altered.^[1]

There are also layers of medium-gray sandy limestone and limy sandstone, only up to 1⁄4–8 in (0.64–20.32 cm) thick, that are inter-stratified with phyllitic siltstone. They can weather to a yellowish-brown colour, and are evenly laminated, and contain very fine grains of quartz, and small amounts of feldspar in a calcite matrix. The formation is up to 9,000 ft (2,700 m) thick in some places, although the true thickness of the formation is unknown, as the base of it is not exposed.^[1]

References

1. Stewart, J. H. "Upper Precambrian and Lower Cambrian Strata, in the Southern Great Basin California and Nevada" (PDF). U.S. Geological Survery. Geological Survey Professional.

• Various Contributors to the Paleobiology Database. "Fossilworks: Gateway to the Paleobiology Database". Retrieved 17 December 2021.