Sly Gap Formation

The Sly Gap Formation is a geologic formation in south-central New Mexico. It preserves fossils dating back to the Frasnian Age of the late Devonian period.

Description
The formation consists of about 114 feet of brown, yellow, or gray limestone and siltstone and brown to greenish-gray shale. It disconformably overlies the Onate Formation and is overlain by the Percha Formation or the Contadero Formation. It pinches out in the west in the Basin and Range province.

Fossils
The formation includes crinoidal siltstone beds and many other beds are fossiliferous, bearing crinoid, brachiopod, bryozoan, anthozoan, cephalopod, gastropod, fish, and coral remains.