STUDIES IN THE NEOCENE OF CALIFORNIA. 441 
THE MONTEREY SERIES. 
Lithology —The rocks of the Monterey series are for the most 
part of a nearly white or light buff color, soft and porous, without 
grit, yet resisting weathering in a remarkable manner. They are 
usually quite thin-bedded, the bedding being very distinct. The 
porosity has been found in some cases to be due to the leaching-out 
of minute shells, probably those of foraminifera. Usually bitu- 
minous, they are locally like a coarse-grained sandstone in which 
the matrix is bitumen. In places they are silicified into chert. 
At Monterey and other places they are rich in infusorial forms, 
diatoms, sponges, etc., so that the beds have been considered a 
vast deposit of such forms. Recently Professor Lawson has 
advanced the idea that the White shale is of volcanic origin.’ It 
is difficult on that theory to account for its occasional presence in 
the Merced series. The series has a thickness of about 1000 feet. 
Occurrence.—The Monterey series is practically lacking on 
the northeastern side of the Santa Cruz Mountains. It is abun- 
dant all over the southwestern side from Spanishtown southward, 
and in fact all through the ranges to the south down into south- 
ern California, while similar strata have been found as far north 
as Oregon. 
Relations —The Monterey series, though containing but few 
fossils, has been recognized from the first as Miocene. Charac- 
teristic fossils are Pecten peckhamt, Gabb ; Tellina congesta, Conrad ; 
Meretriz trasku, Conrad; Mercenaria perlaminosa, Conrad. A 
comparison of the structure alone is sufficient to show that it lies 
unconformably upon the older rocks. 
THE MERCED SERIES. 
The Merced series is of considerable thickness, and is quite 
fossiliferous. Its location is very favorable for the exposure of 
fine sections, so that along the seaboard it is exposed almost 
continuously the whole length of the Santa Cruz Mountains and 
in cliffs averaging perhaps seventy-five feet high, but on Seven 
Mile Beach becoming over 700 feet high. (See Plate IX.) 
™ Univ. of Cal., Bull. Dept. Geol. I., 24. 
