The Shinumo Area. 377 



and parallel to the course of the Colorado River. The greatest 

 lateral gorge extends entirely across the Shinumo amphitheater 

 from Point Sublime on the southeast to the Muav Saddle on 

 the northwest. Only a mile of this lateral gorge is occupied 

 by the master stream of the Shinumo ; the remainder is occupied 

 by two small intermittent streams. The western part of the 

 gorge which extends from the Muav Saddle to Shinumo Creek 

 is drained by Muav Creek and is called the " Muav Canyon " ; 

 the eastern part extending from the Shinumo to Point Sublime 

 is drained by Flint Creek and has no local name. The entire 

 lateral gorge will be referred to as the " Muav-Flint Creek 

 Canyon." This remarkable linear depression is situated upon 

 the line of the West Kaibab fault and has been conditioned by 

 erosion in that line of fracture. Two smaller lateral gorges 

 cross the heart of the amphitheater parallel to the " Muav- 

 Flint Creek Canyon " ; these are situated upon minor lines of 

 fracture. 



It may be noted here that Tapeats amphitheater to the west- 

 ward, in the Kanab division of the canyon, is characterized by 

 similar topographic features where it is crossed by the West 

 Kaibab fault. 



In general the surface of the Kaibab plateau at the rim of 

 the canyon is about 1000 feet higher than that of the Coconino 

 plateau directly opposite. But since the surfaces of the plateaus 

 and of the platforms within the canyon are structural surfaces, 

 elevations diminish progressively southwestward in all parts of 

 the area in accordance with the dip of the underlying rock 

 structure. For example : the elevation of the Kaibab Plateau 

 at the head of the Shinumo amphitheater is 8000 feet ; at the 

 end of the promontory of Point Sublime, four miles southward, 

 it is 7500 feet. The elevation of the Coconino Plateau at the 

 end of Havasupai Point is 6750 feet; at Bass Camp, a mile 

 southwestward, 6652 feet. The eastern end of Powell Plateau 

 at Dutton Point is 7555 feet ; the western end is 6600 feet. 

 Within the canyon the elevation of the Esplanade platform on 

 the north side of the river below Point Sublime is 6250 feet ; 

 on the south side of the river below Bass Camp, 5400 feet. 

 In the eastern part of the area the Tonto platform is 3500 feet ; 

 in the western part, 2700 feet. 



The elevation of the surface of the Colorado Piver where it 

 enters the area on the east is 2250 feet ; where it leaves the 

 area on the west, 2150 feet, — a drop of 100 feet in 10 miles. 

 The river at Bass Ferry is 300 feet wide and 50 feet deep, with 

 a rise of 40 feet at time of high water. 



The greatest drops in the shortest linear distance in the area 

 are at Dutton Point, where a drop of 5355 feet to the river is 

 accomplished in a distance of three miles ; and at Havasupai 



