Gable Creek Formation
The Goose Rock Conglomerate (GRC) found within the boundary of the Sheep Rock unit is a portion of the Gable Creek formation (GCF). The GCF encompasses a wide swath of late cretaceous river deposits trending East-Southeast. The conglomerate outcrop in the monument, with its well-rounded river rocks stuck in a sand stone matrix, would have been near the mouth of a large river and looked similar to a modern delta, like the Nile delta in Egypt. Though there haven’t been any dinosaur fossils found in the park from this formation, further down the geologic section there was a plesiosaur excavated from a similar unit of the GCF. The overall Gable Creek Formation portrays trends of high energy fluvial systems (river deposits) to marine alluvial fans (mudstones and siltstones).