DISTRIBUTION 'OF WATER IN OIL FIELDS. 
27 
In the Westside held many of the waters above the od sands are 
under considerable head, and water flowed at the surface from some 
wells for several years. Some of these top waters are very corrosive 
and have caused considerable damage by attacking and destroying 
the casing used to prevent their entrance into the oil sands. Strong 
water sands are generally encountered near the tar sand zone, and 
many of these waters contain hydrogen sulphide and are known as 
sulphur waters. In the deeper or eastern part of the Westside field 
there is a water sand a short distance above the oil zone but farther 
up the rise to the west this same sand carries oil. In most localities 
a similar condition apparently exists in a sand near the base of the 
oil zone; to the east this sand carries the “bottom water /’ but up 
the rise it is oil bearing and the first water below the oil is in the 
upper part of the Oligocene (?) shale. In general the water below 
the oil zone is confined under considerable pressure, and even now 
rises within a few hundred feet of the surface. 
Owing to the southerly pitch of the anticline on which the Eastside 
field is situated the strata outcrop a short distance west of the north¬ 
ern end of the field but at the southern end are deeply buried. As the 
beds dip rather steeply to the east in the northern part of the field, 
and as there is apparently no structural barrier to the east to restrict 
circulation, a relatively free passage is afforded such water as seeps 
in at the outcrop. In most sands the water is therefore not under 
very high head. It is not so highly mineralized as in the Westside 
field and is characterized by a low proportion of chloride. However, 
toward the southern end of the Eastside field the circulation is more 
restricted, and the average head is therefore higher and the percent¬ 
age of dissolved matter, especially chloride, is greater. The occur¬ 
rence and distribution of the water in the Eastside field is not yet 
thoroughly understood and presents many puzzling irregularities. 
LOST HILLS FIELD. 
The Lost Hills field extends in a narrow belt along the axis of a 
* well-defined anticline, the continuation of that which dominates the 
structure in the Coalinga field. Most of the strata penetrated by the 
wells probably do not outcrop, and conditions are therefore not favor¬ 
able for free circulation. On the west or inclosed slope of the anti¬ 
cline very salty water is obtained at relatively shallow depths, in 
some places within a few hundred feet of the surface, but farther east 
the shallow water contains a high proportion of sulphates. From the 
scanty information available it appears that the water near the oil 
zone is very salty and is confined under considerable pressure. 
McKTTTRICK FIELD. 
The McKittrick field is characterized by more complex structural 
features than any other field in San Joaquin Valley. In a general 
