94 MAEION EXPEDITION TO DAVIS STRAIT AND BAFFIN BAY 



Jacobshaven Glacier, about 250 feet high and about 4 miles wide, is 

 reputed to produce the largest and most picturesque bergs in tlie 

 north, ranging from 130 to 325 feet in height. Helland (1876. p. KHi) 

 measured one 396 feet to its top, and Drygalski (1895, p. 381) re- 

 corded another 425 feet high, but the usual dimension of a large 

 berg is given as 220 feet. Many of the bergs in Jacobshavn Fjord 

 according to reports, tower higher above the sea than does the glacier 

 front from which they calved, all of which is considered proof of 

 buoyancy as the cause of calving. The bottom of Jacobshavn valle\ 

 and upper fjord has a relatively easy, gradual slope, two important 

 features leading to the production of large icebergs. The glacici 

 front during the period 1880 to 1892 suffered several oscillations, the 

 final result of which has been a retreat of approximately 6 miles. 

 The rate of movement is 45 to 65 feet per day: faster in the middle 

 than on the sides, and swifter on the top surface than on the under- 

 side. Our estimate of the number of sizable bergs now emitted from 

 the fjord mouth is 1,350 annually. 



SorxH Greenland Glaciers 



The heads of nearly all the fjords in southwest Greenland are 

 filled with ice tongues which, after the fast ice has left the fjord, 

 calve growlers and small lumps throughout the summer. The twc 

 southwest fjords in which the Marion cruised. Arsuk and Godthaab 

 contained a few scattered growlers, and without doubt the other! 

 fjords between Cape Farewell and Disko Bay were similarly char- 

 acterized. The fact that the southern fjords are so much narroAvei, 

 and shallower near their heads than those in Disko Bay and north-i 

 ward is one of the principal reasons that no sizable masses of ice aro 

 discharged. 



The outstanding glacial feature of the southern section is the hugt; 

 ice lobe which protrudes from the inland cap and fronts the sea foil 

 11 miles in the vicinity of Frederickshaab. Despite its large pro 

 portions no icebergs are produced, because the end melts at the samd 

 rate as it moves forward, the two processes thus maintaining a more 

 or less fixed state of equilibrium. With the description of Freder i 

 ickshaab Glacier we complete the accoimt of the tidewater glacier 

 points from the northern extremity of Greenland down its west 

 side to Cape Farewell. There are 150 to 175 sizeable glaciers in thij 

 distance, of which only about 15 per cent contribute icebergs to thti 

 North Atlantic 



Rate of Productivity of Iceberg Glaciers 



In the following list is an estimate of the number of sizable ice- 

 bergs that are discharged annually from the so-called dangerous 

 tidewater glaciers. By the term " sizable " we mean bergs that ii 

 unhinderecl are sufficiently large to complete the long journey out oi 

 the Arctic into the western North Atlantic. The data are taken froir 

 all available sources mentioned in the text. 



