STRUCTURES OF BASIN RANGES 



65 



this is due partly to the fact that the present position of this structure 

 is not the original one. Since its formation the thrust-plane also 

 has been tilted in marked degree. In point of time, the formation 

 of the thrust-plane long antedates the uprising of the present moun- 

 tain blocks. 



T/tvi^U ?u 



Fig. 2 



A few miles to the north, in the same range, is another lofty point 

 called Caballo Peak. There are clearly shown in- this place the lime- 

 stone beds completely overriding the lower beds, the first mentioned 

 now reposing nearly horizontally on inclined strata. Fig. 2 is a 

 sketch of the peak as it appears from the south. 



Fig. 3 



Another system of faults, the age of which is quite recent, also 

 exists. These dislocations run transverse to the other two and to 

 the axis of the range. As they appear in the canyon walls (at~ZV, 

 Fig. 1), a sketch of them (Fig. 3) is annexed. 



There are, then, in the Sierra de los Caballos at least three very 

 distinct periods of faulting. The first was before the formation of 



