356 E. HUNTINGTON GLACIAL PERIOD IN NON-GLACIATED REGIONS 



Tarim river. The same is true of countless other rivers, especially in 

 arid regions. It is probable that changes in rivers have been much more 

 widespread than changes in glaciers. Hence the term "fluvial" is quite 

 as appropriate as the term "glacial." It has been much less used simply 

 because the behavior of rivers under the influence of climatic changes has 

 been studied much less than has that of glaciers. 



3. LACU8TRAL FEATURES 



At the lower end of the Tarim river the lake of Lop-Nor furnishes an 

 example of still another kind of result produced by changes of climate. 

 Today the lake is a shallow reedy swamp. Old shorelines at various eleva- 

 tions up to 600 feet (see plate 31, p. 368) indicate that during the Glacial 

 period its size was enormously greater than now, although during inter- 

 glacial epochs there is reason to believe that it contracted to small propor- 

 tions. Other examples of lakes which expanded during the Glacial period 

 might easily be cited. Moreover, in America and Europe a great number 

 of new lakes of a different type, such as those of Minnesota or Switzer- 

 land, were formed at that time. Glacial lakes are almost coextensive 

 with glacial deposits, and are one of the most striking results of climatic 

 changes ; therefore "lacustral" is a term of the same order of importance 

 as "glacial" and "fluvial" and might equally well be used as a general 

 term. 



Types and Eesults of Changes of Climate as distinguished from 

 THE Agents producing tpie Eesults 



The terms glacial, fluvial, and lacustral are derived from three inor- 

 ganic agents whose behavior changes markedly under the influence of 

 changes of climate. In place of these another set of terms is often used, 

 denoting the type of change which gives rise to the varied behavior of the 

 inorganic agents. The most common of these are moist and di*y, cold 

 and warm, pluvial and arid. For general use they- are no better than the 

 terms based on the agents. They are equally local and partial, and they 

 assume a knowledge which Ave do not possess. We do not yet know 

 whether the Pleistocene changes of climate were due to variations in pre- 

 cipitation, in temperature, or in botli. Tliere is good reason to believe 

 that the changes produced an oscillation between moister and drier con- 

 ditions, for this would be the case whether the rainfall or the temperature 

 varied; increased rainfall would mean an absolutely greater amount of 

 water, and lower temperature would diminish the rate of evaporation so 

 that the available supply of water would l)e increased. The changes in 

 different parts of the earth, however, must have been of very diverse na- 



