310 ELEMENTARY GEOLOGY 
Mountain Types. — Mountains may belong to either 
of two types, —those due to folding, or those formed by 
faulting. The faulted mountain block is very simple. 
On one side of a fault plane the strata are uplifted, 
Fig. 183. 
Diagram of fault-block mountain ridges. 
and frequently up- 
turned, so that the 
layers are left in 
an inclined posi- 
tion. These fault- 
block mountains 
(Figs. 183 and 
184), which are 
common in the 
Great Basin of the West, sometimes pass gradually 
into mountains of monoclinal folds. 
The fault-block 
mountain has a steep face on the side of the fault, 
and a gentle slope on the side toward which the 
strata are dipping. 
Fic. 184. 
Monoclinal and fault-block mountains in plateau of Colorado River. 
Of the folded mountains there are various types. 
The simplest is the monoclinal mountain (Fig. 184), in 
which, as in the fault-block type, there is a single 
ridge produced. Next in simplicity is the anticlinal 
