STRUCTURAL GEOLOGY. 



geologists that at least 11,000 feet of thickness has been re- 

 moved from the whole mountainous and hilly portions of 

 the British Isles, and by American geologists that 20,000 



FIG. 160. Section across middle Tennessee. The dotted lines show the amount of 

 matter removed. 



feet have been removed from the Appalachian region. 

 This has all taken place since the Palaeozoic, which is 

 certainly not more than one quarter of the recorded history 

 of the earth. But the finest examples are from the Pla- 

 teau region. Fig. 161 represents a portion of the Uintah 



PIG. 161. Uintah Mountains upper part restored, showing fault ; lower part show- 

 ing the present condition as produced by erosion. (After Powell.) 



Mountains, the lower portion as it really is, the upper as 

 it would be if restored with its great fault. According to 

 Powell, 25,000 feet have been removed from the whole 

 area represented, and this, too, since the beginning of 

 the Tertiary, which is but a small fraction of geological 

 time. According to Powell and Dutton, over the whole 



