438 LTTE VO OLNAL NOP MGIOEOGN: 
has been traced from outcrop to outcrop from San Francisco, 
through the San Bruno Mountains to Point San Pedro, and down 
to Pescadero where there is for about four miles a continuous 
exposure of the series with a perpendicular dip. At one end of 
this series were found characteristic Miocene fossils, such as 
Turritella hoffmannt. Yhis clue was then followed back into the 
mountains to other localities yielding a more abundant fauna 
from which may be mentioned Ostrea titan and Liropecten estrel- 
lanus. 
Having thus shown that a part at least of what has been 
known as the San Francisco sandstone is of Miocene age, it is 
believed that most, if not all, of those localities from which 
Ostrea titan and the associated fauna have been reported will be 
found to show the presence of the Pescadero series. 
In Bear Creek Valley near Haakerville fucoids occur in a 
light-colored sandstone. Mr. Gabb correlates these rocks with 
what has since been shown to be Tejon (Eocene) in the Monte 
Diablo region. As the strata near Haakerville are believed to 
form part of the Pescadero series, some evidence is thus afforded 
that the Pescadero series is in part of Tejon age. 
In the head waters of Stevens’ Creek, and in Alum Rock 
Canyon in the Mount Hamilton Range near San Jose, are found 
the fossiliferous strata of the Pescadero series. 
Lithology and stratigraphy-—The Pescadero rocks may be 
described under three facies, the first two of which everywhere 
grade into each other, the last being more distinct. 
The first is typically developed at Point San Pedro. The 
exposure there consists of dark and black shales and shaly 
sandstones which, while showing finer bedding, are distinctly 
bedded in layers of one to three inches or more in thickness. 
These beds weather into soft yellow layers. This facies is well 
exposed in San Francisco in the deep cut on Second street. The 
second facies is the sandstone described by Whitney as the San 
Francisco sandstone; a heavy-bedded sandstone, yellow or brown 
where weathered, but a dark gray blue where freshly exposed. 
In places the beds are a foot or two in thickness, and the strati- 
