cldridge.] PETROLEUM FIELDS OF CALIFORNIA. 311 
occupies an area north of the river of approximately 12 square miles, 
extending but a few hundred feet south of the stream. The general 
trend of the oil-yielding zone is N. 40° W. , coincident with the strike 
l ' of the rocks. The field has excellent railway facilities, and an 8-inch 
pipe line to Point Richmond, on San Francisco Bay, about 300 miles 
distant, is under construction. In addition, there is a tank storage 
capacity in the field of nearly 2,000,000 barrels. Refineries, also, are 
nearing completion. The production of the field at the time of the 
writer's visit was approximately 3,000 cars a month, actual shipments. 
In topographic position the field lies at the edge of the uplands of 
k the San Joaquin Valley, 12 miles from the base of the Sierras, and on 
the southwest slope of the low ridge which separates Kern River 
from its tributary, Poso Creek, about 7 miles to the north. Although 
immediately adjacent to the fertile farms of the valley, the surface 
aspect of the region itself is that of a desert hopelessly beyond recla- 
mation. The strata underlying are soft and yielding to atmospheric 
agents, and lie at but a shallow dip (SW.,), and as a result, erosion 
has transformed the area for many miles into typical "bad lands." 
South of the river a mesa country prevails. 
The surface geology of the Kern River field is comparatively sim- 
ple. The principal geologic formation of the region adjacent on the 
east is determined by its fossils to be of Lower Miocene age. This 
passes beneath the productive area, but whether upon more detailed 
examination some of the surficial beds of this area will not be found 
to be representative of the San Pablo is an open question. The strata 
of the Lower Miocene include conglomerates, sandstones, and clays, 
the several members of this series into which it may be differentiated 
upon physical or other grounds arranging themselves in broad or nar- 
row zones of outcrop according to the thickness to which they have 
been developed and the angle of their always gentle dip. But while 
the differentiation of horizons mentioned is comparatively distinct 
over broad areas, there are local gradations from one zone to another 
that frequently render it impossible to trace a maintenance of regu- 
larity in the succession of strata. The entire series of beds, in fact, 
has the appearance of a shore deposit along the granite range of the 
Sierra, in which currents and waves have played their part in the dis- 
tribution of materials, with the result that a sandstone at one point 
may thicken or thin, and, according to conditions, be replaced by clay 
or conglomerate, which, in their turn, again act in like manner. This 
relation of the sediments one to another, which is evident from the 
surface outcrops, is especially emphasized in the hundreds of wells 
bored in the 12 square miles of the Kern River field. Even in the 
wells of a single company, where the records have been uniformly 
kept, this variation of sediments is a conspicuous feature, and it is 
impossible for one to say from the record of one well what may be 
expected in a hole to be drilled at a distance of 200, 400, or 600 feet 
