70 



MAEIOX EXPEDITION TO DAVIS STRAIT AND BAFFIN BAY 



Glaciation in Greenland 



Greenland, sixth largest of continents, discharges every year some- 

 thing like 15.000 sizable icebergs. The continent, with the American 



Arctic Archipelago, 



IS so 

 placed that it nearly blocks 

 off polar communication on 

 the west, but with Spitz- 

 bergen to the east it forms 

 a connection between the 

 Atlantic and the polar 

 basins. 245 miles in width. 



The general physiography 

 of Greenland and of its ice 

 sheet, the points of iceberg 

 discharge, and the approxi- 

 mate number of bergs pro- 

 duced in time and place are 

 discussed in the following 

 pages but other subjects not 

 so closely related to ice- 

 bergs, such as the origin of 

 the inland ice, its tempera- 

 ture, structure, snow limits, 

 mechanics of motion, etc., 

 are omitted as leading too 

 far afield. 



Our present knowledge of 

 the inland ice comes from 

 the records of various short 

 excursions toward the in- 

 terior, and also from nearly 

 a dozen complete crossings 

 between the east and west 

 coasts. If we exclude the 

 northern unglaciated sec- 

 tion, composed of sedimen- 

 tary layers, practically all 

 of the plateau on which 

 the inland ice lies is of 

 gneiss, sloping gently to- 

 ward the northwest. Basalt 

 outpourings of the Tertiary 

 period are visible around 

 the unglaciated fringe on 

 the western side at Disko 

 Bay and on the east coast 

 in the vicinity of Scoresby 

 Sound and Jameson Land. 

 Koch (1928, p. 438) con- 

 structed longitudinal eleva- 

 tions of the continent, using 

 as ordinate values the heights of the land along each coast. These 

 profiles plainly show the general sha])e of the land border as it slopes 

 from the south toward the north, but probably the most important 

 physiographical point revealed on tliem is the "V-shaped cut mi(hvay 



The Topography of the Greenland Ice 

 AND A Transverse Section 



Figure 36. — The ice cap is composed of two 

 and possibly tliree domes. aU of which obtain 

 the greatest altitude in the south, with more 

 gradually deceuding slopes facing the north. 

 (Figure after de Quervain and Mercanton. 

 W20.) 



