[joHxXston] pleistocene OSCILLATIONS 19 



second period of advance of the ice-sheet was interrupted by a partial 

 retreat of the ice followed by a readvance, and depression of the land 

 during the second period took place mainly after the last advance 

 of the ice, but during the time of occupancy of the region by the ice. 

 The amount of uplift increases in the direction of the maximum 

 accumulation of the ice; and the uplift took place comparatively 

 rapidly and at a fairly uniform rate. It is, therefore, probably 

 isostatic in character. The coincidence of depression and uplift with 

 the advance and retreat of ice during the first period of glaciation 

 suggests that these crustal movements were also isostatic in character. 

 The fact, however, that during the second period of glaciation de- 

 pression of the land took place mainly during the latest stage of 

 glaciation, is difficult of explanation under the theory of isostasy. 



—33 



