46 



MAEION^ EXPEDITIOX TO DAVIS STEAIT AND BAFFIN BAY 



fit all, does so in August, but the predominant circulation soon carries 

 it across Xortli Water. The immobility of the fast ice in the northern 

 tributaries of Baffin Bay, often foreshadows a secondary maximum of 

 pack ice to the head Avaters some times in late summer. 



The ice cover of Baffin Bay varies greatly in size from year to 

 year, or over a group of years. ^- During some summers the central 

 portions are well open to navigation and reasonably safe for the 

 metal hulls of ordinary ships of commerce. During these years the 

 only pack is the west ice, shrunk to a narrow belt close to the shore 

 (except for the normal shore lead), from Cape Kater to Cape Mercy. 

 Such conditions were found in the summer of 1928 by the Marion 

 expedition when the 36-mile wide pack off Cape Dier occupied a total 

 area of only 18,000 square miles. Nevertheless the ice was heavy and 

 thick enough to prevent the passage of the Marion to the coast. -^^ At 

 this time the pack consisted of glacons 5 to 10 feet in diameter and 



Open Pack ice in Summer— West Side of Davis strait 



Figure 23. — The open summer condition of tlie pack oflf Cape Dier, Baffin Land, as 

 found by the Marion expedition in August, 1928. Note the small pool of water on 

 the glagon in the foreground, formed by the melting of ice. Fresh water is thus 

 always to be found during summer, even great distances at sea in the polar 

 regions. (Official photograph, Marion expedition.) 



of larger glacons up to 50 to To feet across. The fact that the ice was 

 quite thick, rising 2 and 3 feet above the surface and extending down 

 8 to 10 feet, testifies to a much more northern source. The outer 

 edge of the pack was fairly open, but 15 miles inside, there was very 

 little open water in wdiich to navigate. The southern edge was met 

 in the offing of Cumberland Gulf, latitude 64° 36' N., longitude 

 59° 10' W. 



^ Munn (1923, p. 65) comments on the annual variations of the middle ice in Baffin 

 Bay, where there was a very small amount in the summers of 1920 and 1921, and practi- 

 cally none in 1922. The three years' deficiency, Munn suggests, may have been due to an 

 ice jam in some of the ice-choked entering sounds, viz, Jones Sound, Smith Sound, and 

 Lancaster Sound. He claims that when such jams break away a heavy and extensive 

 " middle pack " may be expected in Baffin Bay, and to a less extent to the southward. 

 He is also of the opinion that a smooth, quiet summer allows the middle ice to spread 

 farther abroad, causing a surface layer of cold water and favoring the formation of more 

 ice freezing the following winter. 



^The Danish Meteorological Institute (Annually, 1928, p. 3) states that pack-ice 

 conditions in Davis Strait and Baffin Bay the summer of 1928 were favorable. 



