Curtis Formation
Geologic formation in Utah
From Wikipedia, the free encyclopedia
The Curtis Formation is a geologic formation in Utah. It preserves fossils dating back to the Callovian age of the Jurassic period.
| Curtis Formation | |
|---|---|
| Stratigraphic range: | |
 Curtis Formation type | |
| Type | Formation |
| Unit of | San Rafael Group |
| Underlies | Summerville Formation |
| Overlies | Entrada Sandstone |
| Lithology | |
| Primary | Sandstone |
| Other | Mudstone, limestone |
| Location | |
| Coordinates | 39.126665°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 |
Description
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 (39.126665°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]
