408 Ward — Geology of the Little Colorado Valley. 



been worn away, primarily by the action of water, but for a 

 very long period there can be no doubt that wind has been the 

 more potent agency. There is evidence throughout that entire 

 region that the amount of precipitation was formerly much 

 greater than at present, and in so speaking I do not refer to 

 a very remote date geologically, but to a period which was 

 probably post-Tertiary. Indeed, from the present condition of 

 many of the regions where we know that the early Indians 

 dwelt, and who must necessarily have had access to water, now 

 perfectly dry, with all sources of water so remote that they can 

 no longer be inhabited, it must be inferred that there has been 

 a change in the climate within the period of human occupancy. 

 Certain it is that water is doing very little relatively in this 

 region now, while the agency of wind is conspicuously marked 

 wherever it can produce effects. The peculiar form of these 

 buttes is not such as water could have produced, while it is 

 precisely the form that wind would naturally produce, acting 

 upon the very tine and soft materials, somewhat resembling 

 ashes, that compose these buttes. 



Further evidence of this, if any were needed, is found in the 

 fact that in approaching the general escarpment, which bounds 

 these plains, the buttes tend to lose their isolated character and 

 form ridges projecting out from the cliffs. It never happens 

 that an entire valley or plain is covered by a single system of 

 buttes. These systems are separated by wide intervals, often 

 of nearly flat country, but through which it can be easily seen 

 that water once flowed, at least in the form of temporary floods, 

 and in such a manner as to have swept away every vestige of 

 the former plateau, and in crossing which there are encountered 

 one or several wide beds to which the term " wash " is popularly 

 applied. In descending the Little Colorado this condition of 

 things is not met with until within some 8 or 10 miles of the 

 Lee's Ferry road. A large system of buttes is then found 

 extending some 5 or 6 miles down the river and across the 

 plain to the first terrace, a distance of 3 to 5 miles ; then occurs 

 the first wash, 2 miles in width, followed by another system of 

 buttes, which is nearly due east of Tanner's Crossing, and in 

 which most of the bones were collected by our party. There 

 is then another wide wash, but the next system of buttes does 

 not reach the river, but trends off in a direction nearly due 

 north. There is still another wash before the great Moencopie 

 Wash is reached, the direction of which is such as to be highly 

 favorable for the preservation of these buttes, and accordingly 

 we find their greatest development, so far as this region is con- 

 cerned, along the Moencopie Wash. They do not however 

 follow the stream up in the direction of Tuba City, but con- 

 tinue to trend northward along the wide valley that lies to 

 the west of Willow Springs and Echo Cliffs. 



