An outstanding achievement of the Section of Hydrology has been the work of the Committee on Glaciers in assembling the existing records of the advance and retreat of the glaciers in the Western States and in Alaska, encouraging various agencies in making periodic observations, systematizing and standardizing the work, and providing for the compilation and preservation of the data obtained from year to year.
The fluctuation of lake levels is a closely related subject that is equally fundamental in the study of hydrology. In 1922 I published a map giving the distribution of 68 Pleistocene lakes in the Basin and Range province and showed that the desiccation of these lakes could have been caused by change in temperature as well as change in precipitation (Geol. Soc. Amer. Bull., v. 33. pp. 541–552. 1922). Abundant and convincing evidences of changes in climate in the Pleistocene epoch or at its end are afforded both by the ancient drift-sheets and by the ancient lake features, but the question as to the relative importance of changes in temperature and changes in precipitation is still very obscure.
