192 GUIDEBOOK OF THE WESTERN UNITED STATES. 
The structure or attitude of the beds in this part of the canyon is 
simple. The rocks rise abruptly at an angle of 30° from the shale 
valley on the north, but they soon flatten and for some distance lie 
flat or dip slightly toward the southwest. The railroad follows the 
valley of Salt Creek, but the bends of the creek are so short that 
they do not everywhere accommodate the railroad, and about a mile 
erin Mack it cuts 
through one of the 
small bends by a 
short tunnel in the 
sandstone member of 
the McElmo. 
About a quarter of 
a mile beyond mile- 
post 472 the railroad 
reaches the river, and 
from this point to 
Westwater it follows 
the right bank. The canyon, because of its red color, is generally 
called Ruby Canyon, but the most strongly marked red rocks do not 
ager until the traveler is about half a mile below 
e siding named Ruby. Here the massive sandstone 
ates underlies the McEImo comes up suddenly in a 
great fold,®® which may be seen on the opposite side 
of the river. (See fig. 50.) The uppermost bed in this fold is not red 
but nearly ae although are it is stained pink from the 
overlying —— 
shale. The hits 
sandstone (La Plata) 
has a thickness of 
nearly 100 feet, but 
below it is a bed o 
somewhat softer sand- 
stone, which is deep red. The fold is very short but steep, the beds 
having a dip of about 45°. The angle of dip decreases, however, and 
in a very short distance the beds lie practically flat. 
Figure 50.—Short fold in massive sandstone (on the left 
of the westbound train) opposite Ruby siding, below 
Mack. 
y- 
oe + ite - 
er 473 mil 
Figure 51.—Different types of anticlines. 
“The rock folds in the plateau dis- 
trict of Colorado and Utah are differ- 
ent from those which the traveler has 
io: 
are nearly equally diag in all parts, 
aS shown in A, figu In the pla- 
teau region the ae effect of an 
anticline may be the same, but the 
location and form of ai fold pati be 
very different; as shown in The 
beds are very strongly fe on the 
flanks of the anticline, but the sh 
affected by the fold is cad narr 
The traveler may see many such yo 
as that shown in B Se e he reaches 
Salt Lake City. 
