Vor. IIT] ANDERSON—FURTHER STRATIGRAPHIC STUDY 21 
be so classed. From this locality these shales can be followed 
with more or less continuity northward to the Devil’s Den and 
to near Coalinga. The Monterey shales and the underlying 
Temblor beds, as they occur along the hills to the south and 
east of Coalinga, have already been described in the former 
paper. To the north of Jacalitos, if the Monterey shales occur 
at all, they are in extremely reduced thickness or in modified 
form. 
In the eastern part of the Coalinga field, certain beds occupy- 
ing the stratigraphic position of the Monterey, have a thick- 
ness of only 250 to 300 feet. In their outcrop along the hills 
in the northern part of the field, they are variously colored, 
white, yellow, or red, and have at most points a decidedly 
sandy appearance. The “Red Hills” to the north of the prop- 
erty of the “California Oil Fields, Ltd.” form an exposure 
that is conspicuous on account of its brick-red color. This 
can be easily followed northward to the Cantua creek and 
beyond, though its color is not persistent. This member of 
the Miocene was, in the former paper, described as “a yellow 
sand”? and included with the Coalinga beds. In the wells 
drilled in the eastern part of the field this member appears 
as a bluish sandy shale which is commonly called the “Big 
Blue’. The buff, yellow, or red color seen in the outcrops 
is probably due to the oxide of iron derived from the decom- 
position of certain iron-bearing minerals. With a good lens 
grains of serpentine and other talcous minerals can be de- 
tected in these shales. Their separation from the Temblor 
beds in the field to the north of Coalinga is for convenience 
in logical treatment rather than for emphasis of their strati- 
graphic prominence. 
To the north of the Cantua creek these shales are even more 
sandy than farther to the south. It is not unlikely that there 
is a gradual thinning out of the Monterey shales from the 
Temblor valley northward to the Cantua creek, but this can 
not now be affirmed. South of the Temblor valley a vast 
series of white shale follows the range as far as Sunset and 
then swings eastward toward the San Emidio, becoming more 
and more sandy toward the east. No direct evidence is at 
