346 PROCEEDINGS OF THE NATIONAL MUSEUM. vou. xxxuv. 
Dr. John C. Branner, Dr. J. F. Newsom, and the many students who 
have assisted in accumulating the collection, for the privilege of 
working over the material. 
GEOLOGIC FORMATIONS. 
General statement—There are thirteen distinct formations in- 
volved in the geology of the Santa Cruz quadrangle. Of these the 
oldest is the basement complex of granitic rocks, schists, and lime- 
stone. Above these are the Franciscan, probably of upper Jurassic 
age; Knoxville, lower Cretaceous; Chico, upper Cretaceous; undiffer- 
entiated Eocene, probably representing the lower part of this epoch; 
probable lower Oligocene sandstone and San Lorenzo formation, 
Oligocene; Vaqueros, lower Miocene; Monterey, middle Miocene; 
Santa Margarita, upper Miocene; Purisima, upper Miocene to middle 
Pliocene; Merced, marine upper Pliocene and Pleistocene; fresh 
water upper Pliocene and Pleistocene, and Quaternary. 
CRETACEOUS. 
Knoxville formation, lower Cretaceous—The beds of Knoxville 
age in the Santa Cruz Mountains are made up of conglomerate, sand- 
stone, and shale. They cover only small areas in the Santa Cruz 
quadrangle and are confined entirely to the northeastern or Santa 
Clara Valley side of the mountain range. The fauna is small but 
very characteristic, and contains species that are usually found at 
the fossiliferous localities of the Knoxville in other parts of the 
State. The fauna of this formation as represented in the Santa Cruz 
quadrangle is as follows: 
List of Knoaville, lower Cretaceous, fossils from the Santa Cruz quadrangle. 
PELECYPODA. 
Aucella crassicollis Keyserling. Aucella piochii Gabb. 
GASTEROPODA. 
Amberlya dilleri Stanton. 
CEPTIALOPODA. 
?Hoplites, species. 
Chico formation, upper Cretaceous.—The only fossiliferous Chico 
rocks exposed in the quadrangle extend along the coast from near 
the mouth of Pescadero Creek southward to Afio Nuevo Bay, a dis- 
tance of 12 miles. This area varies in width from one-half to 24 
miles, and is at places covered partially by a thin layer of Quaternary 
eravels and sands. The Chico strata along the coast are made up for 
the most part of hard siliceous shales, sandstones, and massive, coarse 
conglomerate. The total thickness exposed is believed to be about 
9,400 feet. The strata dip at high angles, and have been sharply 
