Chalk Butte Formation

Chalk Butte Formation
Stratigraphic range: Tortonian-Zanclean (Hemphillian)
~10.3–4.9 Ma
TypeFormation
ThicknessAbout 538 feet
Lithology
PrimaryTuffaceous sandstones, siltstones, conglomerates
OtherTuff, ash beds, freshwater limestone
Location
Coordinates43°36′N 117°30′W / 43.6°N 117.5°W / 43.6; -117.5
Approximate paleocoordinates44°18′N 114°36′W / 44.3°N 114.6°W / 44.3; -114.6
RegionMalheur County, Oregon
CountryUnited States
Type section
Named forChalk Butte
Chalk Butte Formation is located in the United States
Chalk Butte Formation
Chalk Butte Formation (the United States)
Chalk Butte Formation is located in Oregon
Chalk Butte Formation
Chalk Butte Formation (Oregon)

The Chalk Butte Formation is a geologic formation in Oregon, which forms a part of the Idaho Group. It preserves fossils dating back to the Neogene period. 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. The predominant rock types are tuffaceous sandstones, siltstones, and conglomerates with smaller amounts of tuff, ash beds, and freshwater limestone. A partial section at the type location determined the formation to be about 538 feet thick.

Fossil content

The following fossils have been reported from the formation:

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