

792 



DYNAMICAL GEOLOGY. 



In most regions of faults, the 

 strata have been so denuded that 

 they are indicated only by the dif- 

 ference in age of the strata brought 

 into conjunction. But, if not thus 

 worn away, they would form lines 

 of abrupt elevation. Powell has 

 described monoclinal mountain 

 ridges in the Colorado Basin and 

 Uinta Mountains, which were thus 

 made; and other facts have been 

 brought out by Gilbert. 



The annexed cut, by Powell, 

 represents a portion of the Col- 

 orado Basin, with its one-sided 

 folds (p. 789), its faults and mon- 

 oclinal uplifts along the faults. 

 The names of the faults at H., T., 

 and folds at W. K., E. K., and P., 

 are given in the description under- 

 neath the cut. 



A bend often becomes a break, 

 and sometimes also the course of 

 a fault. Powell draws attention 

 to this, in the case of the Colorado 

 Basin, pointing out one such at W. 

 K. (West Kaibab), E. K. (East 

 Kaibab), and P. (Paria fold). 

 Fig. 1146, from his memoir, is 

 intended to illustrate the displace- 

 ment in the Uinta Mountain, and 

 Fig. 1147 the Kaibab displace- 

 ment. The elevation by the fault- 

 ing at W. K. is 2,000 feet; at 

 E. K., 3,000 feet; at P., 1,800 

 feet. 



Another example of the change 

 of a fold to a fracture and fault 

 is illustrated in Figs. 1148-1150 

 representing a case in the Alps, 

 figured by Heim in his work on 

 Mountain-making. 



