RECENT CHANGES IN GLACIER REGIONS. 325 



imbibed. Wliere rivers are running over its surface, as is the case in mid- 

 summer, then it is no wonder that we find the ice itself moving at the rate 

 of twenty meters a day, or perliaps even much more in some localities. In 

 the winter, on the other hand, the motion, if not entirely stopped, seems to 

 be nearly so, as we may infer from the observations made during spring and 

 autumn. That this retardation of the tlow of the ice during the cold season 

 should be more marked than it is in the case of the Alpine glaciers is not to 

 be wondered at, when we consider the great length of the Polar winter. 



In view of what has been stated in the preceding pages, we consider it 

 not unreasonable to suppose that climatic and topographical conditions might 

 possibly so have arranged themselves, at a former epoch, that there should 

 have been in certain regions an accumulation of ice or snow, or of both, 

 independently of any elevation of the land or range of mountains. To bring 

 this about, a low mean temperature and a large amount of precipitation 

 would be required, a condition not sufficiently realized at the present time 

 except on high land. The nearest approach to the desired combination is 

 found in certain parts of the Polar regions, as has been shown in the preced- 

 ing pages. But the conditions of the Polar lands and seas are such that it is 

 extremely difficult to assume their existence in other zones, with any con- 

 ceivable arrangement of land, or modification of climate. These circum- 

 stances must be kept in mind while discussing the possible or probable former 

 spread of ice and snow over parts of the earth's surface where they do not 

 now occur. In the course of that discussion the application of the facts and 

 considerations which have been brought forward in the present section will 

 be found. 



Sectiox III. — Recent Changes in Glacier Regions. 



The object of the present section is to describe and explain the changes 

 which are now taking place in glacier regions, or, in other words, to indicate 

 what variations in the size and position of the ice masses of various countries 

 have occurred within comparatively few years, and especially during the 

 jiast half-centiny. The aim in view in doing this is, to throw light on the 

 nature and potency of the climatological causes which have been influential 

 in bringing about that much greater extension of the glaciers which, as we 

 shall see in the next section, at a former epoch characterized certain regions 

 of the earth. Knowing where ice and snow occupy the surface permanently 



