DIAMOND PEAK. 



ought to be a monoclinal ridge, but it is not. Again, its base rises chiefly 

 from the thrown side of the fault, but its summit rises many hundreds of 

 feet higher than the plateau on the upheaved side of the fault, and it seems 

 to stand as a contradiction to all known laws of the progress of degrada- 

 tion. On a first visit to the mountain no clew to this enigma was obtained ; 

 on a second visit a better understanding of its lithologic constitution was 

 obtained; and on a third and final visit, which was somewhat protracted, it 

 is believed that the problem was solved. 



All that portion of the base of the peak north of the fault is composed 

 of beds of the Bitter Creek period lying horizontally. On the horizontal 

 beds sandstones and limestones are piled in confusion. In the sandstones 

 no fossils were found, but they resemble lithologically the sandstones of 

 Carboniferous Age. The limestones contain Carboniferous fossils. We 

 have in fact a huge pile of Carboniferous rocks resting on a base of horizon- 

 tal Tertiary sandstones. Now to explain how rocks of an older horizon 

 were piled on a later, w^e have a fact which was discovered after the second 

 visit, but before the third, viz, that there had been two movements along 

 the line of this fault in opposite directions. By the first movement the 

 Uinta or upheaved side was earned about 3,000 feet higher in relation to 

 the beds on the north side than now appears. Subsequently by a reverse 

 movement it fell back the 3,000 feet. After the former displacement and 

 before the latter, we may reasonably suppose that here a great cliff faced 

 northward, for the total displacement by faulting was.about 23,000 feet, and 

 the only hypothesis necessary to the explanation of such a line of cliffs is that 

 displacement was in its later development faster than degradation. Such 

 cliffs would rapidly tumble down, and beds of Carboniferous Age might 

 thus be placed on beds of Tertiary Age. But further, immediately to the 

 west and immediately to the east along this zone of displacement, the line 

 of faulting in its meanders back and forth through the zone of flexure, 

 which has heretofore been described, passes some distance from the upheaved 

 side of the zone toward the thrown side, and hence the beds on the upheaved 

 side dip at a great angle to the northward, and are in a position to more 

 readily tumble down, and doubtless this condition obtained where the 



