Curtis Formation

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Curtis Formation
Stratigraphic range: Callovian
O
S
D
C
P
T
J
K
Pg
N
Curtis Formation type.jpg
Curtis Formation type
Type Formation
Unit of San Rafael Group
Underlies Summerville Formation
Overlies Entrada Sandstone
Lithology
Primary Sandstone
Other Mudstone, limestone
Location
Coordinates 39°07′36″N110°26′51″W / 39.126665°N 110.447615°W / 39.126665; -110.447615
Region Utah
Country United States
Type section
Named forCurtis Point, Emery County, Utah
Named byGilluly and Reeside
Year defined1928
Light-colored beds of the Curtis Formation in abrupt contact with the underlying Entrada Formation. This contact marks the J3 unconformity, Curtis over Slickrock.jpg
Light-colored beds of the Curtis Formation in abrupt contact with the underlying Entrada Formation. This contact marks the J3 unconformity,

The Curtis Formation is a geologic formation in Utah. It preserves fossils dating back to the Callovian age of the Jurassic period.

Contents

Curtis Point, namesake for the Curtis Formation visible as the light gray strata. Curtis Point type locality of the Curtis Formation.jpg
Curtis Point, namesake for the Curtis Formation visible as the light gray strata.

Description

Lightly-colored Curtis Formation at Wild Horse Butte Wild Horse Butte detail.jpg
Lightly-colored Curtis Formation at Wild Horse Butte

The Curtis Formation is composed of shallow marine sandstone, with thin beds of mudstone and minor limestone and gypsum. The sandstone is grayish-green in color and flat bedded or cross bedded. The presence of glauconite and marine invertebrate fossils indicates it was laid down in a shallow marine environment that became hypersaline towards the end of deposition. It represents a high stand of the Sundance Sea in the Callovian. [1]

History of investigation

The formation was first described by Gilluly and Reeside in 1928 and named for exposures in the northeast San Rafael Reef at Curtis Point ( 39°07′36″N110°26′51″W / 39.126665°N 110.447615°W / 39.126665; -110.447615 ). Pipiringos and Imlay reassigned the Curtis as a member of the Stump Formation in 1979, [2] but this was rejected by Peterson in 1988. [3]

Footnotes

  1. Lucas and Anderson 1992
  2. Pipiringos and Imlay 1979
  3. Peterson 1988

See also

References