Article · Wikipedia archive · Last revised Jul 10, 2026

Elko Formation

The Elko Formation, also known as Elko Shale(s), is an oil shale geologic formation in Elko County, northern Nevada, United States. The deltaic and lacustrine shales and limestones preserve fossils dating back to the Middle Eocene of the Paleogene to Middle Miocene of the Neogene period. The frog genus Elkobatrachus and ant species Pseudocamponotus elkoanus were named after the formation.

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Elko Formation
Stratigraphic range: Mid Eocene (Uintan)-Mid Miocene
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TypeFormation
Sub-unitsElko Shale
Lithology
PrimaryShale
OtherLimestone
Location
Coordinates40°48′N 115°48′W / 40.8°N 115.8°W / 40.8; -115.8
Approximate paleocoordinates41°30′N 112°54′W / 41.5°N 112.9°W / 41.5; -112.9
RegionNevada
CountryUnited States
Type section
Named forElko County
Elko Formation (the United States)
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Elko Formation (Nevada)
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Metasequoia occidentalis
Elko Formation source ↗

The Elko Formation, also known as Elko Shale(s), is an oil shale geologic formation in Elko County, northern Nevada, United States. The deltaic and lacustrine shales and limestones preserve fossils dating back to the Middle Eocene of the Paleogene to Middle Miocene of the Neogene period. The frog genus Elkobatrachus and ant species Pseudocamponotus elkoanus were named after the formation.

Description

The formation ranges in age from the Middle Eocene (Uintan), with the underlying lower member dated at 46.1 ± 0.1 Ma and the upper member of the Eocene section dated at 38.9 ± 0.3 Ma.1

A younger section is dated to the Late Eocene to Early Oligocene (37.2 to 28.4 Ma)2 and the Elko Shale member is dated to the Middle Miocene (16.0 to 11.6 Ma).3

Fossil content

The following fossils were reported from the formation:123

See also

See also

References

References

Further reading

Further reading

  • A. C. Henrici and S. R. Haynes. 2006. Elkobatrachus brocki, a new pelobatid (Amphibia: Anura) from the Eocene Elko Formation of Nevada. Annals of Carnegie Museum 75(1):11-35
  • E. H. Taylor. 1941. A new anuran from the middle Miocene of Nevada. University of Kansas Science Bulletin 27(4):61-69
  • F. M. Carpenter. 1930. The Fossil Ants of North America. Bulletin of the Museum of Comparative Zoology, Harvard University 70:1-66