hough] ANTIQUITIES OF GILA-SALT VALLEYS 11 



seems to be, then, the life history of this pueblo from its culmination 

 to its extinction, the gradually enlarging zone of room burials being 

 an index of the decrease of the inhabitants. The evidence invariably 

 shows that no sudden cataclysm overwhelmed the pueblos, no hasty, 

 disorganized abandonment took place, no wars decimated them, but 

 rather that, like a tree, they passed through successive stages of 

 growth, decline, and decay to final extinction, 



CULTURE OF REGION 



Distribution 



The Gila-Salt region is of such great extent and presents such 

 physiographic diversity that it could well have contained within its 

 limits several peoples distinct in language and arts. Transitory 

 tribes moved across it and local populations inhabited almost inac- 

 cessible valleys, cultures mingled on the indefinite boundaries, and 

 there were displacements of one tribe by another; but as a whole, in 

 respect to arts, this section of the Southwest is uniform and charac- 

 teristic. Bearing in mind the topography, it is found that the ancient 

 settlements were distributed in three zones of elevation, each environ- 

 ment inducing certain modifications of culture. The zones are — 



1. Lower, the fluvial plain of the lower Salt and Gila rivers; 



2. Middle, the piedmont, crossed by the San Francisco and upper 

 Gila rivers; and 



3. Upper, the escarpment, with basins, terraces, and cienagas, and 

 the sources of the Gila, San Francisco, Salt, and* Mimbres. 



These zones do not follow a definite contour, the course being 

 irregular, like an isotherm, since river valleys carry to greater eleva- 

 tions the fauna and flora of lower zones. 



AS AFFECTED BY MINERAL ENVIRONMENT 



Geologically the region is composed of igneous formations of great 

 variety, almost entirely hiding the basal rocks. In general, the 

 features shown are cappings of extrusive basalts covering softer 

 rocks, such as tufas, the latter often conglomeritic, and grayish 

 amorphous rocks frequently containing crystals. As a result of 

 erosion, loose masses of basalt are scattered more or less thickly over 

 the country, rendering the roads tortuous and difficult of travel. 

 The valleys along streams are narrow and at intervals show small 

 deposits of alluvium forming the first terrace, generally from 6 to 8 

 feet thick. Rising abruptly from this is a second terrace having 

 steep slopes banked with masses of flat-ovate, smoothly polished hand 

 stones of quartz, quartzite, porphyry, basalt, etc. This terrace is 



