NATURAL AREAS AND REGIONS 



93 



sphere during the maximum develop- 

 ment of the Pleistocene glaciation. 

 Here the balance between precipitation 

 and refrigeration on the one hand, and 

 evaporation and melting and run-off 

 on the other, is so nice that in the cen- 

 turies that the ice-cap has been under 

 observation, little change in its extent 

 or volume has been noticed. 



The interior of the ice-cap is relatively 

 level, conforming to the general slope 

 and elevation of the plateau on which 

 it lies, but cast into drifts and domes 

 like sand-dunes by the prevailing winds. 

 Thus the highest places on the ice-cap 

 are the two centers of elevation, on the 

 seventy-third para lei and the sixty- 

 fifth parallel. The ice-cap in the in- 

 terior portion is composed of thousands 

 of feet of thicknesses of ice in the lower 

 strata, and of recrystallized snow near 

 the surface. The surface snow of the 

 interior portion of the ice-cap does not 

 melt and become running water, and 

 then freeze to ice, but recrystalhzes 

 slowly into ice. 



Along the margin of the ice-cap, where 

 the ice annually melts, and forms water 

 that either freezes again, or runs off 

 the surface in the thousands of brooks 

 and streamlets that flow turbulently 

 and torrentially to the sea in the short 

 summer season, the surface is exceed- 

 ingly broken and rough, and isolated 

 peaks and tracts of bare rock, called 

 "nunataks" project from the ice. The 

 very edge of the ice itself may be a 

 perpendicular wall, revealing the strati- 

 fication of the ice-mass; a gentle slope 

 that spreads out over the plateau on the 

 bed of a valley; or it may be concealed 

 under some of the local neve of the 

 outer headlands. 



Glaciers, varying in width from a few 

 hundred feet to hundreds of miles, move 

 forward from the ice-cap itself along 

 every valley and cleft. Some of these 

 glaciers reach the sea and discharge 

 vast and numerous ice-bergs; others 

 move so slowly that they melt back as 

 fast as they advance, and so do not 

 yield any bergs; others do not reach the 

 sea at all, and melt awaj^ back from the 

 coast, the so-called "dead" glaciers 



Climale 



The climate of Greenland is char- 

 acteristically arctic not only because of 

 the high latitude, but also because of 

 the pronounced influence of the ex- 

 tensive inland ice-cap and the ice- 

 burdened waters that border the entire 

 island. The great masses of ice tend 

 to lower the temperature in both sum- 

 mer and winter, but along the coast tiie 

 tempering influence of open leads and 

 pools of water in relative proximity to 

 most of the coast modifies the rigor of 

 the climate in winter and makes it 

 more equable in summer. 



The seasonal variations in tempera- 

 ture are not so wide as in a great un- 

 glaciated land mass like Siberia, but 

 sudden fluctuations due to varying 

 winds, and to the combined effect of 

 wind-direction and topography, are as 

 great in range as anywhere in the world. 



Winds 



Whenever the wind blows off the ice- 

 fields and the cold waters from the north, 

 west, or east, the temperature falls; 

 whenever it blows from the south and 

 southwest off the warm waters of the 

 Gulf Stream the temperature rises fast. 

 Whenever the "fohn," that wind pecu- 

 liar to certain alpine or plateau regions — 

 like Alpine Europe or the western part 

 of the United States — begins to come 

 down off the plateau heights of Green- 

 land, the temperature rises incredibly 

 fast and suddenly; and since both the 

 east and west coasts of the island are 

 topographically favorable to the de- 

 velopment of the "fohn," its char- 

 acteristic occurrence is frequent and 

 effective. The "fohn" may continue 

 for only a few hours, but it may jircvail 

 for several daj's. Under the innuoncc 

 of this warm, drj-ing wind, the toinpora- 

 ture may rise as much as 80° in a day, 

 or as much as 45° in an hour, sometimes 

 evaporating several inches of snow 

 during its continuance. 



Temperature 



The mean tenip(>rature in soutliern 

 Greenland is only a half degree above 



