SMITHSONIAN EXPLORATIONS, I93O 23 



separates the head of Bright Angel Creek, up which the Kaibab trail 

 leads to the North Rim, from the pass into Nankoweap Creek, where 

 our field investigations were to be conducted. However, as the winter 

 snow still lay deep in the woods, offering too much difficulty for laden 

 pack animals, our plans had to be changed. Doctor Stoyanow and f, 

 with food and equipment, were transported by a Park Service auto- 

 mobile 90 miles to South Canyon. Meanwhile our riding and unladen 

 pack animals were driven by a straighter route through the forest to 

 the rendezvous. 



In order to understand this narrative more fully, both the geography 

 and the geologic structure of the Grand Canyon must lie called to 

 mind. The Grand Canyon of the Colorado is developed where the 

 river cuts deeply into almost horizontal strata on the flanks of the 

 Kaibab Plateau, the higher portions of which attain an elevation of 

 9,500 feet above sea-level. As this mountainous mass was bowed up, 

 the river, which previously probably followed a rather straight south- 

 west course, was forced to make a wide sweep to the east, where, after 

 notching into the surface, it cut the canyon. As a consequence, the 

 Grand Canyon is now a great curved gorge. 



Work in the canyon is very difficult. Besides the obstacle of its 

 vast depth, the harder horizontal strata everywhere form cliffs, and 

 since several of the geologic formations are rather thick, these vertical 

 faces often reach several thousand feet in height. However, a thou- 

 sand foot cliff is not needed to stop one's progress — a vertical wall 

 only a few feet high, adjacent to steep slopes, becomes unscalable when 

 the footing is insecure. The uplift of the Kaibab Plateau having 

 occurred rather gently, few breaks in the horizontal formations re- 

 sulted, and therefore weathering has not torn the rocks to pieces to 

 form talus slopes over which trails might be made. Furthermore, in 

 this dry region few side streams enter the river, particularly on the 

 south rim where the gentle dip of the beds carries all water southward 

 from the margins of the uplift. Therefore trails in the Grand Canyon 

 exist only where advantage can be taken of slight natural breaks, and 

 there only by the expenditure of considerable sums of money. 



South Canyon, just east of the Park boundary and south of House 

 Rock Valley, is a small dry valley cutting into the Kaibab Plateau and 

 draining into the Marble Canyon. Our camp was made in the former 

 home of " Uncle " Jim Owen ; now a subsidiary National Forest 

 ranger station — and some of the claws of the 2,200 cougars he is 

 said to have killed are still seen tacked to the barn. In the cool Kaibab 

 forest nearby, deer as well as the big cats are exceedingly plentiful. 



