Geology of the Area:
Antelope Creek is an outcropping of the Chico Formation, a geological strata found in Northern California and Southern Oregon containing fossils of the Campanian age in the Cretaceous period. Dinosaur fauna have been recovered from the area, but Antelope Creek mainly contains mollusks.
Paleontology of the Fossils:
Fossils found near Antelope creek consist of Santonian-Campanian ammonites and inoceramid bivalves. Additionally, Hyphantoceras venustum, Baculites capensis, Bostrychoceras elongatum, Inoceramus schmidti and Baculites chicoensis have been found in the area.
J.W. Haggart, “Upper Cretaceous (Santonian-Campanian) ammonite and inoceramid biostratigraphy of the Chico Formation, California,” (Cretaceous Research 1984) <http://www.sciencedirect.com/science/article/pii/S0195667184800208>