352 PAPAGUER1A 



This characteristic waterflow has reacted on the topography 

 during the eons of geologic history, and has developed a config- 

 uration no less distinctive than the drainage systems. To the 

 traveler by rail along the northern border of Papagueria the 

 region seems one of remarkably rugose and irregular mountain 

 ranges, buttes, picachos, and precipice-walled mesas ; for the 

 jagged mountains are always in sight and the clear air brings 

 them close to the eye. At first the traveler in the saddle sees 

 the region in similar light, the exceeding ruggedness of the 

 mountains giving them undue prominence; but after spending 

 days in traversing the intermontane plains and hours in cross- 

 ing or circumscribing ranges and mesas for a month or two he 

 learns to see the land-forms in true proportion, and finds that 

 only a fifth or a tenth of the surface is mountain and four-fifths 

 or nine-tenths plain or valley so smooth as easily to be traversed 

 by pack-animals, and for the most part by wheels. So rugged 

 are the mountains and so smooth the plains that the region has 

 been likened by a careful observer to a series of great ranges 

 buried to their ears in alluvial deposits; yet more thoughtful study 

 shows that half the area of the plains is smoothly planed rock 

 similar to that of the mountains, the planing being the work of 

 the sheetfloods into which the freshet waters gather. In gen- 

 eral, the plains incline toward the great trough half filled with 

 the waters of the California!! gulf; and, on crossing the north- 

 westerly-southeasterly trending ranges toward the gulf, each in- 

 termontane plain is found to lie lower than the last, down to the 

 tide-swept shore. This inclination is a part of that southwest- 

 ward tilting which accompanied the uplifting of the great plateau 

 region and the birth of the Colorado canyon. In arid Papa- 

 gueria, where the work of the feeble streams is long drawn out, 

 it has resulted in a regressive erosion, whereby the streams flow, 

 ing southward and westward have cut far into and often through 

 the ranges in which the waters gather, pushing the divides into 

 the plains beyond. The habitability of Papagueria is largely 

 due to this fact, for it is only in the narrow gorges cut into and 

 through the ranges by regressive stream -work that the scant 

 ground-water approaches the surface in springs or seepage from 

 the sand-washes.* 



The Papago Indians, primitive and present holders of this dis- 

 trict, are preeminently children of the desert. So strongly acl- 



*The topography and its development in this interesting region are set forth in 

 greater fullness in "Sheetflood Erosion" (Bull. Geol. Soe. Am., vol. 8, 1897, pp. 87-112)- 



