THE SAN ANDREAS RIFT AS A GEOMORPHIC FEATURE. 43 
(See plate 228.) The fissure follows its northern side for several miles and then, bending 
a little toward the south, crosses the canyon and takes a course for Tejon Pass. The 
granitic mountains upon the north of the canyon rise with exceedingly steep slopes, the 
rocks of which have been thoroly shattered. Immense quantities of rock débris have been 
brought down the gulches, building up in the main canyon a succession of large and steep 
débris fans. So much débris has been carried down the canyon that it has been blocked 
at the point where it turns toward old Fort Tejon, and has thus given rise to Castac Lake. 
The Rift crosses the divide at the gap known as Tejon Pass. Here there are features due 
to two movements. Descending a few hundred feet, we find ourselves in a long valley, 
extending about 10 miles in a direction a little south of east. Springs, marshes, and two 
ponds mark the line of the Rift from Gorman Station easterly. ‘ (Plates 238 and 24a.) 
At German Station, several miles below Gorman, there is a wonderfully regular ridge 
forming a marsh. In this vicinity the earthquake of 1857 is reported to have done much 
damage, shaking down an adobe house and breaking up the road. The little lake upon 
the divide halfway between Gorman Station and Neenach P.O. is due to débris brought 
down from the hills upon the south thru which the Rift zone passes. The Rift follows a 
very regular and straight course, a little south of east, along the mountain slopes south 
of Antelope Valley. Thru the most of the distance, as far as Palmdale, it occupies a 
series of valleys shut off by considerable elevations from the open slopes of Antelope 
Valley. After traversing the northern slopes of Libre and Sawmill Mountains, the Rift 
crosses the head of Oak Grove Canyon, then another small canyon with branches east- 
ward and westward along the break, and eastward of this a long canyon opening out to 
the fertile valleys about Lake Elizabeth. 
Lake Elizabeth and Lower Lake (plate 248) are both due to the blocking of the drain- 
age of two valleys extending along the Rift. These valleys lie on the slope of the range 
toward the desert (Antelope Valley), but their outlet is southward by a narrow canyon 
thru the heart of the mountains lying between the desert and Santa Clara River. A 
low escarpment along the southern side of the valley in which Lake Elizabeth lies, and 
eastward, is replaced by a lofty rounded ridge which appears to be due to some one of the 
movements along the old fault. For several miles east of the lake (plate 25a) the dis- 
tinctive and characteristic features of the Rift are not as easily made out, altho the ridge 
just mentioned is full of springs and exhibits a widespread landslide topography. ‘Toward 
the eastern end of this ridge small hollows and a low, indistinct escarpment again appear. 
The ridge separates Leones Valley, a fertile and well-watered district 5 or 6 miles long, 
from the open Mojave desert on the north. 
From Leones Valley to and beyond the point where the Rift zone crosses the Southern 
Pacific Railway, a constant succession of cienegas is found on the upper side; that is, 
on the side toward the mountains. Movements have evidently been so often, repeated 
and so intense along the Rift as to grind up the rocks and produce an impervious clayey 
stratum, bringing to the surface the water percolating downward thru the gravels of 
the waste slopes. A mile west of Alpine Station on the Southern Pacific Railway, 
there begins another escarpment with its abrupt face toward the south. This extends to 
and across the railroad. South of the escarpment the surface has sunk so as to form a 
basin. (Plates 258n and 26a.) This has been artificially enlarged and used as a reservoir 
for irrigation about Palmdale. The main escarpment is 40 to 50 feet high in places, 
and where the railroad crosses it there appear to be two, an older and a younger one. 
From the summit of the ridge marking the Rift west of Alpine, an extensive view east- 
ward is obtained. The long desert waste plain leading up to the foot of the mountains 
on the south (San Gabriel Range) exhibits a strikingly interesting feature. It is not 
continuous across the line of the Rift, but shows a break with the uplift upon the lower 
side. The amount of displacement appears to be between 200 and 300 feet. 
