on the Navajo Reservation. 101 



red rock rising 300 to 500 feet above the valley at its western 

 base and presenting slopes exceeding 60 degrees. The ridge is 

 unbroken except where trenched by the rock-walled canyon of 

 the Chinle, and its crest is set with red sandstone teeth cul- 

 minating in a massive projection locally known as Mule Ear. 

 West of this primary cuesta are a series of hogbacks in parallel 

 position formed of the upturned edges of eastward-dipping 

 sandstone strata. 



The surface of the entire area is trenched by closely-spaced, 

 deep-cut canyons with perpendicular walls; and innumerable 

 mesas and buttes occupy the inter-canyon spaces. South of 

 Mule Ear Pass the water channels are tributary to the Chinle, 

 either directly down the back slope of the Comb Monocline or 

 by devious routes among the ridges to the west. Drainage 

 north of Mule Ear enters the San Juan, the master stream of 

 the northeastern portion of the Navajo Reservation. The 

 Chinle canyon is deeply rilled with alluvium into which an 

 inner canyon 10-30 feet deep has been cut ; elsewhere a mantle 

 of soil is lacking except for inconspicuous patches of recently 

 disintegrated rock and piles of scattered dunes. Vegetation 

 is therefore scanty except for isolated tufts of grass and 

 hardy weeds which spring up rapidly following showers. 

 Greasewood and yucca in widely-spaced groups are dominant 

 in the lower lands ; on the crest of the Comb, sage, pinon and 

 cedar are able to maintain themselves. 



The absence of soil, the steep gradients of the canyons, the 

 scant annual precipitation which is made up of sudden short- 

 lived showers, and the high values of rock absorption and of 

 evaporation give to the water courses in this region their typical 

 desert character, viz.: well-formed channels admirably adapted 

 for carrying water but functioning only for a few hours at a 

 time. 



The fields of erratics may be reached from stations on the 

 Denver and Bio Grande Railway at distances estimated as 

 follows: Farmington, N. M., 80 miles; Dolores, Colorado, 110 

 miles ; Thompson Springs, Utah, 160 miles. From the south 

 a passable road, about 190 miles long, extends from Flagstaff, 

 Arizona, via Tuba and Kayenta. From Gallup, K". M, the 

 field may be reached, via Fort Defiance and Chinle, by a 

 traverse of approximately 120 miles. The scarcity of Water 

 and of feed for stock, rather than distance, are the significant 

 factors of travel in this region. The Moses Rock and Mule 

 Ear fields may be studied with Moses Rock Spring as a base ; 

 in the vicinity of Garnet Ridge no water is available except 

 that remaining in rock pockets for a few days following heavy 

 rains. Saddle horse, pack train and a competent guide are 

 essential accompaniments of detailed work. 



