167 
the edge of the desert into the valley of Cajon Creek. Beyond the 
summit cut the traveler gets a view of the deep valley of this creek, 
which crosses the main range and cuts deeply through its rocky ledges. 
Only a smali branch of this stream heads near the summit, however, 
the valley proper heading a few miles west back of the San Gabriel 
Range, in a part of the slope that is considerably higher than the 
gap crossed by the railway. An outline map showing these relations 
is given in figure 40. 
After passing through the deep cut west of Summit, the train fol- 
lows a winding course, mainly to the west and southwest, along the 
side of steep slopes descending into the canyon of Cajon Creek. Along 
the railway grade descending from Summit there are many deep 
cuts through projecting spurs. These cuts reveal thick deposits of 
sand, gravel, and loose-textured sandstone which extend continu- 
THE SANTA FE ROUTE, 
SAN GABRIEL 
MTS. 
FIGURE 40,—Bird’s-eye view of Cajon Pass and vicinity, California, st 
figuration near the Santa Fe Railway. 
ously northward into the Mohave Desert. These materials abut 
against the steep slopes of ledges of old rocks in the mountain ranges 
on the south, and beds apparently having a thickness of more than 
2,000 feet are exposed in the descent from Cajon Summit to Cajon 
Creek. Cajon Creek flows east and south with sinuous course, finally 
running through a pass between the San Bernardino Range on the 
+1, L Pe 3 Ph poet Me A 
This to the westward 
has been caused by a great | to t y defin 
of the San Gabriel Range. There were 
pass 
fault or series of parallel faults of rela- 
tively recent age geologically, crossing 
ern extension of the San Francisco earth- 
quake rift, extend for many miles along 
+h she +.¢4L Q Dp a Pp cn 
co) 
Pa +1 b eae? See | ict = es 2 owt 
At the pass their northwesterly course 
crosses the mountains diagonally, so that 
several planes of movement not far apart 
with huge slivers or narrow blocks of 
schists and other rocks between them. 
The latest uplift apparently was on the 
northeast side, for the San Be i 
ge 2 to be the most recently 
lains in 
top of the San Gabriel Range. 
