78 TEE ICE AGE IN NORTH AMERICA. 



tion. . . . Only the marginal part shows irregularity ; toward 

 the interior the surface grows more and more level, and passes 

 into a plain very slightly rising in the same direction. It has 

 been proved that, ascending its extreme verge, where it has 

 spread like a lava-stream over the lower ground in front of it, 

 the irregularities are chiefly met with up to a height of 2,000 

 feet, but the distance from the margin in which the height is 

 reached varies much. While under 6&J° north latitude, it took 

 twenty-four miles before this elevation was attained ; in 62|° 

 the same height was arrived at in half the distance. . . . 



A general movement of the whole mass from the central re- 

 gions toward the sea is still continued, but it concentrates its 

 force to comparatively few points in the most extraordinary 

 degree. These points are represented by the ice-fiords, through 

 which the annual surplus ice is carried off in the shape of bergs. 

 ... In Danish Greenland are found five of the first, four of 

 the second, and eight of the third (or least productive) class, 

 besides a number of inlets which only receive insignificant 

 fragments. Direct measurements of the velocity have now 

 been applied on three first-rate and one second-rate fiords, all 

 situated between 69° and 71° north latitude. The measure- 

 ments have been repeated during the coldest and the warmest 

 season, and connected with surveying and other investigations 

 of the inlets and their environs. It is now proved that the 

 glacier branches which produce the bergs proceed incessantly 

 at a rate of thirty to fifty feet per diem ; this movement being 

 not at all influenced by the seasons. . . . 



In the ice-fiord of Jakobshavn, which spreads its enormous 

 bergs over Disco Bay, and probably far into the Atlantic, the 

 productive part of the glacier is 4,500 metres (about 2-£ miles) 

 broad. The movement along its middle line, which is quicker 

 than on the sides nearer the shores, can be rated at fifty feet 

 per diem. The bulk of ice here annually forced into the sea 

 would, if taken on the shore, make a mountain two miles long, 

 two miles broad, and 1,000 feet high. The ice-fiord of Tor- 

 sukatak receives four or five branches of the glacier ; the most 

 productive of them is about 9,000 metres (five miles) broad, 

 and moves between sixteen and thirty-two feet per diem. The 

 large Karajak Glacier, about 7,000 metres (four miles) broad, 



