XX BUREAU OF AMERICAN ETHNOLOGY 



annual floods and slowly evaporated during succeeding 

 months, and the greater part of the hroad bottom is 

 swept by the freshets. Within the region lie a number 

 of "mud volcanoes," apparently analogous to the "mud 

 lumps" of the Lower Mississippi, which have attracted 

 much attention by reason of their novelty, though they 

 are quite subordinate to the general features. The entire 

 district affords the closest American parallel to the valley 

 of the Nile, not only in physical conditions, but in the 

 influence of these on human conditions. 



Like northern Africa, the general region is one of 

 extreme aridity, the rainfall (averaging less than 2 inches 

 yearly during the last quarter -century at the typical sta- 

 tion of Mammoth Tanks) being negligible; while the 

 habitable district is well watered by annual freshets of 

 remarkable regularity in period and height. These fresh- 

 ets not only flood but fertilize the riparian lowlands ; they 

 control directly the local flora and somewhat less directly 

 the local fauna, and they regulate the movements, most 

 of the industrial habits, many of the social customs, and 

 much of the mythology of the human population. Dur- 

 ing the greater part of the year water is obtainable only 

 from the shrunken river, on whose banks grow most of 

 the seed -bearing and root -yielding plants available as 

 food, so that the people are led to occupy the lower bot- 

 tom lands. Here the cultivated crop plants are sown in 

 soil soaked by the flood and enriched by its silt deposit, 

 to grow and ripen rapidly under the subtropical sun; 

 here habitations are erected, naturally of light and tem- 

 porary character, and here the small and scattered vil- 

 lages characteristic of the tribe grow up during each late 

 summer and early autimm. The chief crop plants are 

 corn (maize), beans, peas, squashes, and melons, and it is 

 noteworthy that most of these represent the aboriginal 

 plant stocks brought under cultivation in pre-Columbian 

 times. 



Fishing and hunting the abundant waterfowl, as well as 

 other game, contribute to the tribal subsistence, and dur- 

 ing recent years part of the crop of corn, beans, and peas 



