The Curtis Formation is a geologic formation in Utah. It preserves fossils dating back to the Callovian age of the Jurassic period.
Curtis Formation | |
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Stratigraphic range: | |
Type | Formation |
Unit of | San Rafael Group |
Underlies | Summerville Formation |
Overlies | Entrada Sandstone |
Lithology | |
Primary | Sandstone |
Other | Mudstone, limestone |
Location | |
Coordinates | 39°07′36″N 110°26′51″W / 39.126665°N 110.447615°W |
Region | Utah |
Country | United States |
Type section | |
Named for | Curtis Point, Emery County, Utah |
Named by | Gilluly and Reeside |
Year defined | 1928 |
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]
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″N 110°26′51″W / 39.126665°N 110.447615°W). 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]