The Tullock Member is a geologic member in Montana and Wyoming, forming the lowermost part of the Fort Union Formation. It is also known less commonly as the Tullock Formation, forming part of the Fort Union Group.[1] It preserves fossils dating back to the Paleogene period.

Tullock Member
Stratigraphic range: Early Paleocene (Puercan)
TypeMember
Unit ofFort Union Formation
UnderliesLebo Member
OverliesHell Creek Formation (MT), Lance Formation (WY)
Thickness90–400 m (Powder River Basin)
Location
RegionMontana, Wyoming
CountryUnited States
Type section
Named forTullock Creek
Named byRogers and Lee (1923)
Coal stratigraphy of the Powder River Basin (USGS).
Coal stratigraphy of the Powder River Basin (USGS).

See also

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References

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  1. "Geologic Unit: Tullock". National Geologic Map Database. United States Geological Survey. Retrieved 2025-06-01.