Chalk Butte Formation

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Chalk Butte Formation
Stratigraphic range: Tortonian-Zanclean (Hemphillian)
~10.3–4.9  Ma
Type Formation
ThicknessAbout 538 feet
Lithology
PrimaryTuffaceous sandstones, siltstones, conglomerates
OtherTuff, ash beds, freshwater limestone
Location
Coordinates 43°36′N117°30′W / 43.6°N 117.5°W / 43.6; -117.5
Approximate paleocoordinates 44°18′N114°36′W / 44.3°N 114.6°W / 44.3; -114.6
Region Malheur County, Oregon
Country United States
Type section
Named for Chalk Butte
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Chalk Butte Formation (the United States)
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Chalk Butte Formation (Oregon)

The Chalk Butte Formation is a geologic formation in Oregon, which forms a part of the Idaho Group. [1] It preserves fossils dating back to the Neogene period. [2] It was proposed along with the Grassy Mountain Basalt Formation and the Kern Basin Formation as a division of the Idaho Group rocks in the Mitchell Butte Quadrangle. [3] The predominant rock types are tuffaceous sandstones, siltstones, and conglomerates with smaller amounts of tuff, ash beds, and freshwater limestone. [3] A partial section at the type location determined the formation to be about 538 feet thick. [3]

Contents

Fossil content

The following fossils have been reported from the formation: [2] [4]

See also

References

  1. ↑ Chalk Butte Formation at USGS
  2. 1 2 Chalk Butte Formation at Fossilworks.org
  3. 1 2 3 Corcoran, R. E.; Doak, R. A.; Porter, P. W.; Pritchett, F. I.; Privrasky, N. C. (1962). "Geology of the Mitchell Butte Quadrangle, Oregon" (PDF). Geological Map Series. Portland, Oregon: State of Oregon Department of Geology and Mineral Industries. Retrieved 26 June 2024.
  4. ↑ Shotwell, 1970

Bibliography

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