HURRICANE FA ULT IN SOUTHWESTERN UTAH 53 



fered little or no erosion ; hence it must have been poured out 

 before the country had been elevated above the sea long enough 

 to allow extensive erosion — probably long before the comple- 

 tion of the folding. 



THE HURRICANE FAULT THE EARLIER FAULTING. 



After the folding had been completed, the tangential pressure 

 must have been relieved and a strain of another character set up. 

 Instead of compression there seems to have been extension, 

 whereby numerous faults were formed which followed the lines 

 of the old folds, but moved the strata in exactly the opposite 

 direction, so that a new series of steps descended toward the 

 west, and the Basin Range province stood lower, relative to 

 the Plateau province. It is noticeable that the greatest fault 

 took place along the line of the greatest fold, and like it 

 increased from south to north. This Hurricane fault has been 

 traced for fully two hundred miles. For the greater part 

 of the hundred miles which we examined from the Colorado 

 river to Kanarra, the displacement was a true fault, with a lift 

 of from 2,000 to 3,000 feet; but for a short distance at Toquer- 

 ville it passed into a torn flexure, accompanied by an offset of 

 three miles to the west. North of Toquerville the fault is con- 

 cealed by gravel and lava, but reappears at Kanarra, where with 

 a much increased throw it cuts the overturned anticline already 

 mentioned. It has long been recognized that the whole dis- 

 placement of the Hurricane fault did not take place at one time, 

 but was divided between two periods. It is thought, however, 

 that both these periods of faulting were very recent, and there 

 is uncertainty as to the time interval between the two periods 

 and as to the relation which they bear to the cutting of the 

 Colorado canyon. Evidence has been found which seems to 

 show that the first faulting is of early date, possibly in the first 

 part of what Button calls the Miocene, and has no immediate 

 connection with the formation of the Grand Canyon. The 

 second faulting, on the other hand, is of recent date, and accom- 

 panied the single uplift which allowed the cutting of the canyon. 



