126 



MAN AND THE GLACIAL PERIOD. 



Partial subsidence of the Cor- 

 dilleran region, to a level about 

 2,500 feet lower than the present. 

 Long stage of stability. Glaciers 

 of the second period considerably 

 reduced. Upper boulder-clay of 

 the coast probably formed at this 

 time, though perhaps in part dur- 

 ing the second maximum of gla- 

 ciation. 



Renewed elevation of the Cor- 

 dilleran region, with one well- 

 marked pause, during which the 

 littoral stood about 200 feet lower 

 than at present. Glaciers much 

 reduced, and diminishing in con- 

 sequence of general amelioration 

 of climate towards the close of 

 the Glacial period. 



Correlative elevation of the 

 plains, or at least of their west- 

 ern portion, resulting in a condi- 

 tion of equilibrium as between 

 the plains and the Cordillera, 

 their relative levels becoming 

 nearly as at present. Probable 

 formation of the Missouri co- 

 teau along a shore-line during 

 this period of rest. 



Simultaneous elevation of the 

 great plains to about their pres- 

 ent level, with final exclusion of 

 waters in connection with the 

 sea. Lake Agassiz formed and 

 eventually drained towards the 

 close of this period. This simul- 

 taneous movement in elevation 

 of both great areas may probably 

 have been connected with a more 

 general northern elevation of 

 land at the close of the Glacial 

 period. 



In New Zealand the marks of the Glacial period are 

 unequivocal The glaciers which now come down from 

 the lofty mountains upon the South Island of New Zea- 

 land to within a few hundred feet of the sea then de- 

 scended to the sea-level. The longest existing glacier in 

 New Zealand is sixteen miles, but formerly one of them 

 had a length of seventy-eight miles. One of the ancient 

 moraines contains a boulder from thirty to forty feet in 

 diameter, and the amount of glacial debris covering the 

 mountain-sides is said to be enormous. Keports have also 

 been recently brought of signs of ancient glaciers in Aus- 

 tralia. 



According to Darwin, there are distinct signs of glacia- 

 tion upon the plains of Patagonia sixty or seventy miles 

 east of the foot of the mountains, and in the Straits of Ma- 



