20 THE SAN FRANCISCO EARTHQUAKE AND FIRE. 
out any portion of the system which may become crippled. There 
should also be some means of preventing the loss of water which is 
occasioned by breaks in the house service pipes. 
While one of the main conduits was badly damaged wherever it 
crossed the fault, this damage was no greater than that done to any 
other structure that was situated at the fault line. Structures so 
located were torn apart, the gap in the case of a fence (PI. I, B) or 
road (PI. I, A) being from 6 to 20 feet, according to local conditions. 
In the country around Fort Ross there were many trees located on 
the fault that showed the effect of the slip. Great redwood and 
pine trees were either twisted out of normal position or split (PL II) 
from the roots up for distances of 35 feet or more, even when per- 
fectly sound. This splitting action was due to the earth on the west 
of the line of faulting moving the roots on that side, a motion which 
tended to pull the tree apart. Where the tree had some defect or 
was unsound (as from dry rot) the action was even more marked 
and the destruction much greater. Redwood trees grow to great 
heights and are perfectly straight, and to find one out of plumb is 
very unusual. 
Another interesting example of the effect of the slip along the 
line of the fault is a Horded by the Southern Pacific Railroad bridge 
over Pajaro River near Chittenden station. This bridge crosses the 
fault obliquely at a very acute angle — about 10°. It consists of two 
girder shore spans of 50 feet each and three Pratt truss river spans 
of about 100 feet each. The piers and abutments are built of con- 
crete, witli granite coping and bridge seats (PI. XI, A). The bridge 
was badly racked by the movement of the earth, which dragged 
the piers and abutments. The movement of the south abutment 
was about 24. inches, a distance sufficient to leave the girder with- 
out support. The ground also moved a greater distance than the 
abutment — perhaps 8 or 10 inches farther. The movement of the 
earth tending to pull the piers from under the trusses was resisted 
by the anchor bolts, resulting in a cracking of the piers, appar- 
ently on the lines marking the different daily batches of concrete 
used in constructing them. The granite caps were moved out of 
position and many of them cracked, and the anchor bolts were twisted 
and bent. The bridge was put into service by the construction of a 
timber support. 
In the vicinity of Los Gatos, Avhere the line of faulting passes 
through the Santa Cruz Mountains, it crosses the first tunnel of the 
narrow-gage railroad to Santa Cruz near Wrights. In this tunnel 
a portion of the loose roof, of shale on a layer of serpentine or soap- 
stone, caved in, completely closing the tunnel. A house on this fault 
line near Wrights was split in twain, the movement of the earth 
throwing the west side of the house from its foundation (PI. X, B). 
