MINOR GEOLOGICAL EFFECTS OF THE- EARTHQUAKE, 389 
for a hundred yards at a stretch. The slide extends for 0.25 mile on both sides of the 
canyon. A similar carth-avalanche was caused by the earthquake on the ranch of 
Judge Welch, not far from Long Bridge and within 2 miles of Saratoga. Mr. Herre 
reports that here the soil on the northwest side of a small creek coming down from the 
Castle Rock Ridge, was shaken down for perhaps 0.5 mile, tho not continuously. In 
places the slid material filled up the creek-bed and totally changed the contour. It 
destroyed the road to the ranches farther up the canyon, and wrecked some bridges. 
Along the upper part of the area affected, a vineyard was destroyed; while farther down 
the canyon a heavy forest growth, consisting mostly of redwood, oak, alder, and laurel 
was obliterated. This slide lies in the path of the San Andreas fault. 
Mr. Herre further reports a large slide on the Mindego Ranch, 20 miles southwest of 
Palo Alto. Here, on the north side of Alpine Creek, a tract of some 50 acres sank at 
the time of the earthquake, with little or no apparent forward movement. The tract 
sloped to the south and west, and formed part of a great, open hill pasture, with trees 
and underbrush about the lower or creek side. The creek-bed itself is filled with a growth 
of Douglas spruces and other trees. The land, which before the earthquake was steeply 
inclined, is now comparatively level, the eastern and northern part having sunk perhaps 
100 feet, while that on the west has sunk but 10 or 15 feet. The surface of the sunken 
tract was greatly seamed and cracked, and part of it was flooded, owing to the springs 
uncovered; but otherwise it was unchanged in appearance. There was no piling up 
of earth, nor sliding of one portion over another. A fence crost the tract, and the posts 
on it sank so that but a few inches protruded above the surface; while some Douglas 
spruces also sank several feet into the earth. A number of cattle were on the land at 
the time of the earthquake, but were uninjured. It was a work of great difficulty to 
remove them, block and tackle being necessary. The creeck-bed was apparently not 
affected, nor were the trees in it disturbed. There was no apparent movement of the 
earth into the canyon, but the whole mass seems simply to have been dropt from a steep 
slope to a nearly uniform level, surrounded by the high, blank, almost perpendicular 
walls of earth and rock from which it had been sundered. 
Many other earth-avalanches of minor importance were caused by the earthquake 
in various parts of the Santa Cruz Mountains. At Hidden Villa, 2 miles northwest of 
Black Mountain, large blocks of rock are reported to have rolled down the slopes. There 
were numerous slides along Stevens Creek, due chiefly to the caving of the creck banks. 
Along the ridge road southwest of Stevens Creek, sandstone blocks, some of them 6 feet in 
diameter, rolled down the hills toward the creek. Near Half Moon Bay considerable 
masses of granite were dislodged on a steep slope. (Plate 124c.) On the road along 
Pilarcitos Creek, an earth-avalanche brought down big blocks of sandstone upon the 
road. (Plate 1268.) At Boulder Creek a large portion of the soil was shaken loose 
from an abrupt hill 150 feet high, and fell to the level of the ereek, carrying trees with 
it. At the north end of Ben Lomond Mountain, a slide carried trees and brush down 
to the creck. Near Olive Springs, 12 miles north of Santa Cruz, an earth-avalanche 
demolished Loma Prieta Mill and killed several men. At many places on the south side 
of Corte Madera Creek, huge masses of rock had been thrown down from the steep bluffs 
into the road, completely blocking it. About a mile from the summit of the ridge, where 
the Alpine road enters the Page Mill road, a slide carried away the entire roadbed for 
a distance of about 300 feet. On Purissima Creek a slide filled the road for a length 
of about 100 feet; another, between 0.25 mile and 0.5 mile long, dammed the creek to 
a depth of 25 or 30 feet. A large slide close to Wright Station partly dammed the stream. 
On the western slope of the ridge just west of Skyland, several earth-avalanches were 
caused by the shock; and great slides of a similar character occurred on both sides of 
Aptos Creek for 0.75 mile. Besides these, there were many smaller earth-avalanches 
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