Benton Shale

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Benton Shale
Stratigraphic range: Cretaceous
TypeFormation
UnderliesNiobrara Formation
OverliesDakota Sandstone
Lithology
PrimaryShale
OtherLimestone, sandstone, bentonite
Location
RegionMontana, Wyoming, North Dakota, South Dakota, Colorado, Nebraska
CountryUnited States
Type section
Named forFort Benton, Montana

The Benton Shale (also Benton Formation or Benton Group) is a geologic formation in Montana, Wyoming, North Dakota, South Dakota, Colorado, Kansas, and Nebraska.[1] It preserves fossils dating to the Cretaceous Period. The term Benton Limestone has also been used to refer to the chalky portions of the strata, especially the upper beds of the strata presently classified as Greenhorn Limestone. The Benton classification is obsolete in some regions, having been replaced by the ascending sequence Graneros Shale, Greenhorn Limestone, and Carlile Shale.[2][3]

The classification derives its name from Fort Benton, a small city in Montana on the Upper Missouri River.

See also[edit]

References[edit]

  1. ^ National Geologic Map Database - Geolex, USGS
  2. ^ Donald E. Hattin (1962). "Stratigraphy of the Carlile Shale (Upper Cretaceous) in Kansas". State Geological Survey of Kansas. Kansas Geological Survey, University of Kansas, Lawrence, Kansas (Bulletin 156). Retrieved 2018-08-04.
  3. ^ Donald E. Hattin (1962). "Stratigraphy and Depositional Environment of Greenhorn Limestone (Upper Cretaceous) of Kansas". State Geological Survey of Kansas. Kansas Geological Survey, University of Kansas, Lawrence, Kansas (Bulletin 209). Retrieved 2018-08-04.