CONDITIONS OUTSIDE OF SAN FRANCISCO. 115 
formerly the main dam, when the reservoir was smaller than it is 
now. The concrete dam, which was parallel to the fault and of 
course very near to it, was absolutely uninjured (PI. XI, B) ; the 
earth dam, which lay across the fault approximately at right angles, 
showed definite signs of disturbance and lateral displacement. Longi- 
tudinal and transverse cracks appeared on top of the earth dam, and 
some of the former were reported to have extended to a depth of at 
least 3 or 4 feet. The transverse cracks were said to be less well 
defined and to indicate rather a general disturbance on each side of 
the fault line, about one-fourth of a mile away, and was absolutely 
to which it was damaged could not be ascertained. 
San Andreas Lake is retained by a high earth dam. The fault ran 
under the east end of this dam and produced considerable disturb- 
ance over a strip about 150 feet wide, though the dam was not seri- 
ously injured. A concrete culvert inlet w T as connected with this dam, 
and one of the w T orst transverse cracks noted ran diagonally over the 
culvert, but the culvert itself was uninjured. Besides the high con- 
crete dam of Crystal Springs Lake, the water company had another 
smaller concrete dam at Searsville. This dam also was parallel to 
the fault line, about one-fourth of a mile away, and was absolutely 
uninjured. 
The Spring Valley Water Company had three main conduits run- 
ning into San Francisco. One of these, known as the Pilarcitos 
conduit, consisted largely of 22-inch and 30-inch riveted pipe and 
24-inch cast-iron pipe ; some feeders were built of wooden flume. 
The conduit crossed and recrossed the line of the fault, and was so 
badly Avrecked that the company has decided to abandon it — no 
doubt a wise decision, because the location along the line of the fault 
w T as a very bad one. Wherever the conduit crossed the fault line it 
was destroyed. In some places there was a longitudinal displacement 
of as much as 81 inches, which either telescoped the pipe or pulled 
it apart, as the case might be. (Views of these effects are given in 
PI. IX.) It made no difference whether the conduit was in firm 
ground, or in soft ground, or carried on a trestle over marshy ground ; 
the result was the same wherever it crossed the fault. In many 
places where the conduit was carried on trestlework the timber 
showed considerable decay. Whether sound timber structures would 
have withstood the shock seems open to question. (See also PI. 
X,,i.) 
Within the city proper the reservoir known as Lake Honda was 
damaged by the cracking of its concrete lining. It is reported that 
this cracking was due to the displacement of a retaining wall by a 
sliding bank set in motion by the earthquake. 
The distributing mains of the Spring Valley Water Company, 
wherever they passed through soft or made ground, suffered in the 
