80 THE ICE AGE IN NORTH AMERICA. 



Bank supposes the opening of new channels for the outlet 

 of the ice through the fiords may have so relieved the interior 

 as to account for this recedence of the ice.* 



Among the most important observations upon the rate of 

 movement in the glaciers in Greenland are those made by 

 the Norwegian geologist Helland, in the summer of 1875. 

 During that season he made a series of measurements on the 

 glacier that enters the great Jakobshavn Fiord in the north- 

 ern part of Disco Bay, about latitude 70°. The width of 

 this glacier near its mouth he found to be about two miles 

 and a half. The view from the peaks in the vicinity toward 

 the east extended to a continuous ice-field on the distant 

 horizon. The rate of motion reported by Eielland was so 

 great, that scientific men hesitated for some time to credit it. 

 According to his measurements, the Jakobshavn Glacier, in 

 the central portion of its current, was moving more than 

 sixty feet per day, as compared with the three feet per day 

 reported for Alpine glaciers. But the subsequent measure- 

 ments of Steenstrup, given above, and those of my own upon 

 the Muir Glacier in Alaska (made in 1886), amply sustain 

 the conclusions of Helland. 



It is proper to observe here, again, that the movement of 

 glacial ice is affected much less by the slope of its bottom 

 than by the size of the stream itself. The friction of the 

 ice upon the bottom and sides of its channel is so great, that, 

 where the stream is both shallow and narrow, the motion 

 must be almost completely retarded. On doubling the size 



* The list of explorers given by Rink is worthy of being honored, and is as 

 follows : " Geologist K. J. V. Steenstrup (eight summers and two winters) ; 

 Lieutenant G. Holm, of the Royal Navy (five summers and one winter) ; Lieu- 

 tenant R. Hammer, of the Royal Navy (three summers and one winter) ; Lieuten- 

 ant A. D. Jensen, of the Royal Navy (three summers) ; geologist Sylow (two 

 summers) ; painter Groth (two summers) ; supernumerary officer Larsen (one 

 summer) ; Lieutenant Garde, of the Royal Navy (two summers and one winter) ; 

 geologist Knutsen, Norwegian (two summers and one winter) ; geologist Peter- 

 sen (one summer) ; botanist Eberlin (two summers and one winter) ; painter 

 Riis Carstersen (one summer). Steenstrup and Hammer did most on the 

 fiords." 



