ICEBERGS. 
75 
feet above sea-level, bergs over 150 feet high were seldom seen. Most bergs are 
less than a quarter of a mile long and about 70 feet high. The largest bergs seen 
were near King Edward VII Land, where there were many over 150 feet high ; 
they had grounded in places where soundings showed 100 fathoms of watei\ Local 
ice-caps supply few bergs. Mount Melbourne, for example, has its ice-cliffs 
cavernous and overhanging, and we may conclude that years have elapsed since 
bergs separated from them (Fig. 37, p. 65). 
Distribution . — Icebergs float northward along the coast of South Victoria Land 
bearing with them their burden of mud and stones, and soundings seem to show 
that most of this is dropped within the Antarctic Circle. In latitude 67° S. the 
sea-floor proved to consist of mud and ice-scratched stones, whereas only diatom- 
ooze had been obtained in the deeper water of latitude 60° S. The distribution of 
bergs in latitudes which are being constantly navigated is represented on the 
Admiralty Ice-chart, No. 1241, and a short paper by Mr. H. C. Russell* gives 
some measurements as to the sizes of the bergs. For our purpose, however, the 
northerly migration along the coast is the point of interest ; the long string of 
bergs grounded near Cape Adare seemed to have formed a banner-shoal ; melting 
there, they must deposit the moraine brought by them from higher latitudes. 
Icebergs are destroyed by two agents, the sea and the sun. Some bergs float 
north into the warmer waters of more temperate latitudes and are there quickly 
melted. As the berg is undermined by the warm sea-water it becomes top-heavy 
and sometimes turns over, large pieces being broken oft’ in the process. Some 
bergs ground in high latitudes and are only slowly dissolved. At certain stages 
these may float off the shoal and go to swell the mass of drifting ice. 
Bergs containing mud, sand or gravel absorb radiant heat, and some ice is 
melted. The water produced distributes the mud over the surface and the rate of 
destruction is increased; on December 7th, 1903, a hot day, a berg was seen to have 
rivulets over all the sides turned towards the sun. A berg becoming inverted may 
carry mud and stones from the sea-floor above water, and these the sun immediately 
utilizes for the disintegration of the berg. In latitude 77° S., thawing of ice is of 
little importance except in December and January. Melting begins in the middle 
of November, becomes comparatively rapid by the middle of December, continues 
through January, and virtually ceases about the middle of February. 
L 2 
H. C. Russell, Journ. Roy. Soc., New South Wales, 1898 (1897), vol. xxxi, p. 221. 
