162 
THE GEAND CAS^ON DISTEICT. 
POWELL’S PLATEAU. 
This gap is a saddle or col between the Tapeats amphitheater on the 
north and a vast lateral gorge on the south, known as the Muav Canon. 
Erosion has eaten completely through the upper beds of the isthmus which 
formerly connected Powell’s Plateau with the mainland, removing there- 
from about 1,200 feet of strata. The saddle thus formed is therefore 1,200 
feet below us, and to reach the outlying plateau it is necessary to descend 
into and cross the intervening gap. A curious phenomenon is presented 
here. On the spot where we stand it would hardly be seen, but it is very 
conspicuous from points eight or ten miles north or south. One of the 
branches of the West Kaibab multiple fault cuts right across the isthmus 
from north to south, and presents a relation similar to those presented in 
some parts of the Hurricane, Sevier, and other faults. The beds upon the 
western side of the fault flex downwards at a considerable angle as they 
approach the fault-plane. This of itself is a very common thing, and is 
exhibited so frequently in the faults of the Plateau Province that we have 
come to regard it as one of the characteristic features of its displacements. 
The peculiarity here is that at the distance of less than a mile west of the 
fault the beds have come back to the same position they would have occu- 
pied if no fault had occurred. From the summit of the Kaibab there is a 
sensibly uniform dip of the beds to the southwestward, continuing across 
and beyond Powell’s Plateau, and even beyond the river, the inclination 
being about 1|°. This fault comes in as a purely local interruption, affect- 
ing the beds in its immediate vicinity on the west side of the fault-plane 
and having no effect upon them a little distance from it. This singular 
mode of displacement is extremely perplexing when we come to inquire 
into the nature of the causes which have produced faults, and reminds us 
very forcibly how ignorant we are of those causes, and how inapplicable 
are all theories hitherto advanced to explain them. This same dislocation 
continues both north and south of the gap. On the northern side of the 
Tapeats amphitheater the beds and general platform have been dropped by 
the fault, and its efi’ect is continuous west of the fault-plane. South of the 
gap the relation of the beds is apparently the same as at the gap itself, so 
