22 BUREAU OF AMERICAN ETHNOLOGY [bull. M 



more than 8,000 to 10,000 years old, and there is no reason for limiting 

 the age of man m the Southwest to the last few centuries. 



It would be premature to discuss at this time the bearing of the facts 

 of physiography here noted on the facts of culture history to be pre- 

 sented in subsequent papers. It may be suggested, however, that the 

 evidences now at hand indicate that the original culture that arose 

 in the Rio Grande valley was not wholly or mainly dependent on 

 UTigation but that m course of tune it became so. Aridity, therefore, 

 was not originally the dominant factor in shaping the culture of the 

 Southwest. It came to be so ultimately, and in sucli manner that 

 adaptation to the changing conditions was possible. The aridian 

 culture of the Southwest is the result of gradual adaptation. 



In the following paper Professor Henderson presents in detail the 

 results of his study, in the summer of 1910, of the geology and topog- 

 rapliy of a limited area of tlie region under consideration, ]iis obser- 

 vations liaving been made mainly on the Rito de los Frijoles and its 

 vicinity. In the next paper the same writer, m collaboration with 

 Professor Robbins, brings together, under the title "Climate and 

 Evidence of Climatic Changes," the evidences and views that have 

 been set forth touching the important question of possible modifica- 

 tions of climate in the Southwest. 



