210 GUIDEBOOK OF THE WESTERN UNITED STATES. 
The railroad rises steadily until it reaches a local summit at Cliff 
siding, between mileposts 574 and 575, and then begins a rapid de- 
‘ scent to Price River, the master stream in the north 
ich end of Castle Valley. This stream heads on the 
prevation Pet) et Wasatch Plateau, far to the northwest, and flows 
across the north end of the San Rafael Swell, be- 
yond which it joins Green River through a deep canyon cut in the 
Book Cliffs just north of the Beckwith Plateau. The traveler may 
see the entrance to this canyon by looking ahead on the east (right) 
after passing Cliff siding. 
The line of cottonwood trees that marks the course of Price River 
may be seen long before the train has reached the bottom of the valley, 
and their soft green color is very refreshing to the eye that has been 
gazing on the barren expanse of desert just crossed. At Woodside 
the railroad crosses Price River, which the traveler 
Woodside. unaccustomed to this region may not be willing to 
Elevation 4,645 feet. call a river unless he remembers that most of the 
eet inte, Water it normally carries is withdrawn for irri- 
gation farther upstream, and then he may wonder 
that any water at all is left in it at Woodside. 
For a distance of about 3 miles the railroad follows the east bank 
of the river through groves of cottonwood trees and small irrigated 
farms. Its course here lies near the west margin of the belt of shale, and 
the underlying sandstone (Dakota) and the red and green rocks of the 
McElmo may be seen at many places across the river on the left. 
Near milepost 583 the river ceases to follow the shale and swings 11 
from the west, where it has cut a deep and narrow canyon in the 
hard rocks across the north end of the San Rafael Swell. The rail- 
road engineers sought to avoid this canyon by following the broad 
valley that Grassy Creek has cut-in the shale. This valley is the 
extension of the one that the train has followed ever since it left 
Green River, 
The valley was not formed by a downfold in the rocks but simply 
by the erosion of the soft Mancos shale. ‘The traveler may under- 
stand this easily by looking at the higher rocks in the face of the 
Book Cliffs on the east and the lower rocks in the San Rafael Swell 
on the west and noticing that they dip in the same direction—toward 
the northeast. From time to time as the traveler may be able to 
look ahead he can see that apparently the valley is filled and cut off 
by terraces that rise 100 feet or more above the level of the track, 
as shown in figure 56. These terraces appear to bar the further pas- 
sage of the railroad, so it turns to the left a short distance beyond 
Grassy siding and climbs out of the shale valley. In making this 
climb the road turns and twists about some of the barren shale hills, 
a gp ll cleo a 
