GEOLOGICAL OBSERVATIONS 



air, which is 250 metres thick, lies another layer which at a height of about 

 1,000 metres is succeeded by a cold layer of air. The middle layer has 

 through both day and night a temperature of nearly plus 9° C. At a height 

 of 600 metres, then, there is during the night a temperature of 10° C, and 

 during the day it is 6° C. warmer than on the coast. During our hunting 

 expeditions we had rich opportunities to prove that this warmer layer of air 

 was an everyday phenomenon in the most northerly part of Greenland during 

 July and the beginning of August. It would take us too far here to examine 

 the reasons for the existence of this warm layer, but it is obviously of great 

 importance to both plants and animals, and it is surely a contributory cause 

 of the existence of such large ice-free reaches along the north coast of 

 Greenland. 



The lower cold layer of air immediately above the ocean-ice will, of course, 

 protect this from too great a degree of melting, and as one must assume that 

 the under side of the ocean-ice melts, it seems reasonable to deduce that this 

 ice every year becomes thicker upward, as the downfall of the year is partly 

 deposited as a layer of ice on top of one already existing. In exactly the same 

 way the floating inland-ice grows, and, as we have already mentioned, there 

 is in Victoria Fjord no line of demarcation between ocean-ice and glacier-ice. 

 In several other fjords there is a ridge of pressed-up ice between the two types 

 of ice, as the glacier-ice presses forward against the immovable ocean-ice ; but 

 the surface of the ice on both sides of the ridge is perfectly even. Th e thi ck- 

 ness of the ocean-ice may be put at approximately 5 metres, whilst the floating 

 inland-ice may be 30 metres or more, especially some distance behind the edge 

 of the glacier. 



Loose pieces, consisting partly of several years of ocean-ice, partly of float- 

 ing inland-ice, will occasionally drift out from the fjords through channels and 

 lanes or, on rare occasions, when the fjord is ice-free. They may be found 

 in the Polar basin north of Greenland, and are especially common in Robeson 

 Channel. Nares Expedition called this formation " palseocrystic " ice, but 

 not until now has it been known how it arose. The Eskimos call it 

 " Sikussaq " — i.e., ice which resembles the ocean-ice. 



Only in the most northerly regions is the ocean itself covered by inland- 

 ice, but wherever one travels in Greenland one feels this inland-ice as the 

 great background of existence in these latitudes. Against this background life 

 must be viewed, and that which in other and more favoured neighbourhoods 

 may seem mean here, immediately before the Ice Period, becomes rich and 

 remarkable. 



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