70 BUREAU OF AMERICAN ETHNOLOGY [buix. 54 



5. Systematic records of the clianges in area, depth, and outlines 

 of glacier remnants, neve and so-called banks of perpetual snow, 

 including also the time of disappearance in summer of large banks 

 of snow which do not remain throughout the year but appear at the 

 same points je&v after year in the winter. A convenient and safe 

 method of obtaining these records is to photograph each of these 

 fields of snow and ice from the same point on the same day of suc- 

 cessive years. 



6. Botanical evidence offers a most promising and little exploited 

 field, especially the investigation of the extension or contraction 

 of forest areas, the relations of large plant formations to one an- 

 other, and the extent to which trees are dying and the causes of this 

 condition. 



7. The existence of botanical "islands" of certain vegetation of 

 types left in favorable situations as the climate became unsuited 

 for their general distribution and pecuUar adaptations of various 

 types of plants to meet changing conditions would also be important 

 discoveries. 



8. An exhaustive study of the distribution of living and recently 

 extinct faunas, especially forms which do not migrate readily, would 

 doubtless furnish valuable evidence. 



9. A search for ancient springs, irrigation works, reservoirs, and 

 garden or farming plots in localities now far from water. 



