THE EARTH MOVEMENT ON THE FAULT OF APRIL 18, 1906. BEL 
as a single fissure 3 inches wide, trending 8. 538° E. In the lowland to the southeast there 
is little evidence of the fault, but crossing at right angles the county road running north 
and south about a mile east of San Juan, is a band of small cracks 15 feet wide, causing 
the road to sink 8 inches and making a marsh of the field beyond. This is believed to 
be the southernmost point of the recent opening of the fault. No trace of it could be found 
where it would have crost roads beyond, nor were other cracks found or reported in 
this neighborhood. The disturbance affected the banks of the Pajaro River from Chit- 
tenden to Sargent, causing a cracking and sloughing of the banks into the stream but not 
a settling of the stream bed. The San Benito River was similarly shaken for about 3 
miles up from its junction with the Pajaro. Cracks are also noticeable all along the River- 
side road wherever it runs close to the river bank. The damage to the concrete abutments 
of the county bridge across the Pajaro River is due to this crowding in of the alluvial 
banks of the stream. 
The tunnel at Wright Station (E. P. Carey). — Mr. Everett P. Carey reports that he made 
an examination of the tunnel at Wright Station soon after the earthquake, and again on 
February 17, 1907. The result of his observations is incorporated in the following 
memorandum : 
The length of the tunnel is 6,200 feet. Its direction is S. 48° 24’.5 W. A fissure crost 
the tunnel 400 feet from the northeast portal, along which there was a lateral displacement 
of 4.5 feet. ‘The movement on the southwest side was northerly with reference to the north- 
east side. Nothing of this fissure can now be seen, as the tunnel along that part has been 
excavated, the walls timbered and entirely obscured from view. My description rests 
on my examination soon after the earthquake, before any work had been done. The strike 
of this fissure is N. 52° W., making an angle of 80° with the trend of the tunnel, and it dips 
at an angle of about 75° to the west. The walls of the fissure were well smoothed and 
slicken-sided, but I did not determine the direction of the striz. Specimens from this 
fissure indicate that the fault occurred in sandstone, and that much movement had already 
taken place along the same fault in apparently a variety of directions. Specimens secured at 
the time have changed from a damp, sticky, clay-like mass to a relatively dry, hard, and crum- 
bled condition. Streaks of light-colored sandstone occurred in this dark attrition material. 
The damage to the tunnel itself consisted in the caving in of overhead rock; the crushing 
in toward the center of the tunnel of the lateral upright timbers, and the heaving upward 
of the rails, due to the upward displacement of the underlying ties. In some instances 
these ties were broken in the middle. In general the top of the tunnel was carried north or 
northeast with reference to the bottom. This seems to be the prevailing condition in the 
exposed part of the tunnel not yet repaired. : 
I examined with particular care the walls of the tunnel at several points where the 
damage to the timbers appeared to be greatest, more especially between 1,400 feet and 2,200 
feet in from the opening at Wright. At each place I found several fissure lines running 
somewhat irregularly, but in general parallel to the fissure already described 400 feet in 
from the entrance at Wright. These fissures all contained more or less attrition material. 
Three of them I had an opportunity to examine better than the others. In each case two 
distinct sets of striz were found, one set vertical and the other set horizontal. The hori- 
zontal set was clearly more recent than the vertical set, and to all appearances might 
have been formed the day before. The three slicken-sided faults mentioned were the only 
ones that lookt as if recent movement had occurred. The rocks in the tunnel look like 
sandstones and jaspers of Franciscan age. According to the evidence, so far as’it went, the 
whole of the top of the mountain is fissured thruout in such a way that a large movement 
could be distributed among several fissures and thus account for a relatively slight motion 
along any one fissure. The measuring of any minor movements in the tunnel would be 
difficult because of the caving in of the rocks at such points. It would seem, too, that such 
movement could occur without materially altering the line of the tunnel at that point, so 
far as the timbering is concerned. 
As far as learned no recognized fissures or faults have been crost by the workmen thus 
far, except the one 400 feet from the northeast portal. Nothing corresponding to the fissure 
passing Morrell’s house has yet been found in the tunnel. 
