HURRICANE AND TUSHAR FAULTS. 29 



From the Grand Cailon northward for 40 miles it is a nearly simple 

 fault, though in some places it shows comminution of the rocks in the 

 vicinity of the fault plane, and in a few places the beds on the thrown side 

 are turned up. Along the southwestern base of the Markagunt the fracture 

 becomes very complicated. The upper beds have been eroded backward 

 from the fault plane on the lifted side of the fault, and the lower beds on that 

 side have in several places been turned up with a sharp flexure and stand 

 nearly vertical — in one instance have been turned past the vertical. This 

 movement seems to be exceptional, no other instance of the same kind 

 having been seen anywhere. It is difficult to understand by what applica- 

 tion of forces such a contortion could have been effected. The Carbonif- 

 erous has been brought up by it so as to abut against the Tertiary on the 

 thrown side of the fault, and right at the plane of shearing the displace- 

 ment of the lower beds seems to be about 12,000 or 13,000 feet. But 

 away from the fault plane the beds quickly come back to their normal 

 position, with an uplift of about 4,000 feet. A few miles south of this point 

 another equally abnormal displacement occurs. A small branch of the 

 fault runs into the uplift and a huge block seems to have cracked off and 

 rolled over, the beds opening with a V, and fonning a valley of grand 

 dimensions. About six miles north of the great upturn all trace of that 

 peculiar flexure has vanished and the beds are neatly sheared. The Hur- 

 ricane fault nowhere appears to take on the true monoclinal form. The 

 length of this gi-eat displacement is probably more than 200 miles. 



The third great fault is that which lies at the eastern base of the Tu- 

 shar. Most of the faults have their throws to the west, but the throw of 

 the Tushar is to the east. It commences with two branches at the south-- 

 eastern base of the range and the branches converge near the middle of its 

 eastern flank They are obscure and difficult to locate exactly on account 

 of their concealment by the alluvial debris, resulting from the waste of the 

 ancient lava beds and the somewhat chaotic nature of the tract through 

 which they run; for this tract is one of the old centers of eruption. But 

 some well preserved beds of conglomerate turned up on the thrown side 

 and matched with beds appearing above at last revealed them, and the 

 discovery of a series of peculiar trachytic beds on both sides of the fault 



