GLACIER TONGUE - 105 



Tongue. Ou this theory Glacier Tongue is therefore chiefly formed of drift or 

 dune snow. 



Another possible theory as to its mode of origin is that it is a shrinking remnant 

 of a lobe of the old Ross Barrier Avhich formerly overflowed the saddle to the east of 

 Glacier Tongue. Such a lobe might have been deflected from east to west, just as 

 are the modern blizzard winds by the resistant massif of Erebus directly opposed to 

 its northward movement. 



In regard to the question as to whether Glacier Tongue is aground or afloat, it 

 may be stated that on February 13, 1908, soundings were taken at a point a little 

 over half a mile back from the west end of Glacier Tongue, which reached bottom at 

 157| fathoms. The arming of the lead brought up a quantity of serpulse and 

 siliceous sponge spicules ; in fact, the bottom of the sea there must be as white as 

 snow with the siliceous sponge spicules. Obviously we are confronted here on a 

 smaller scale with a similar problem to that which has already been discussed in 

 connection with the Drygalski Ice Barrier Tongue. The surface of Glacier Tongue 

 nowhere exceeding about 40 feet above sea-level in this locality, the thickness of 

 the ice cannot be greater than about 400 feet at this spot, whereas the depth of the 

 sea is 945 feet. If this same depth was maintained right under the glacier, there 

 should be a depth of 585 feet of sea water between the bottom of the glacier ice and 

 the floor of the sea. 



As already stated, at about 3 miles back from this seaward end the surface of 

 Glacier Tongue rises 70 to 80 feet above sea-level, and if the sea shallows slightly in 

 an easterly direction towards the land, as is likely, the eastern portion of the glacier 

 is probably aground. The chief question now is, is the western half of the glacier 

 afloat or aground ? Obviously the presence or absence of a well-marked tide crack 

 should settle this question. Certainly a small, but not well-defined, tide crack was 

 noticed by us on the northern side of Glacier Tongue. It was suggestive of a slight, 

 though not strongly marked, differential movement between the sea ice and the 

 glacier ice. One would have expected a more pronounced tidal crack had Glacier 

 Tongue at this point been resting firmly upon the bedrock. When we were on the 

 Nimrod, lying under the lee of Glacier Tongue, we tried to determine whether or not 

 the glacier was rising and falling with the tide, as evidenced by the level of the 

 ship's rail in relation to the marginal cliff" of the glacier and the position of the 

 wave-worn groove with its icicles at the base of the glacier cliff" in relation to sea- 

 level. We were unable to notice any appreciable difference in level in either case 

 during a rise and fall of the tide. We must therefore conclude provisionally that 

 the western part of the Tongue is afloat.* 



* This view has subsequently been con&med by Captain R. F. Scott's British Antarctic Expedi- 

 tion of 1910-13. Two miles in length of the seaward end of Glacier Tongue broke away during a 

 blizzard on March 1, 1911, and was found later by T. Griffith Taylor's party near Cape Bernacchi, 

 at the entrance to the Ferrar Glacier Valley, about 50 miles to the W.N.W. 



