TRACES OF FORMER GLACIATION 289 



The Dellbridge Islands, as well as Inaccessible Island and Tent Island, rising 

 to heights of respectively 500 feet and 400 feet, have obviously been heavily 

 glaciated, and the summits, at all events that of Tent Island, strewn with erratics. 

 Observation Hill, now about 700 feet above the level of the neighbouring 

 Great Ice Barrier at Pram Point, has obviously been glaciated over its summit. 

 It would be a matter of great interest and importance to ascertain the exact 

 height of the old moraines distributed along the great promontory of Minna 

 Bluff, and around the flanks of the extinct volcanoes, Mount Discovery and Mount 

 Morning. 



The excellent drawings of the late Dr. E. A. Wilson when on the Discovery 

 Expedition, together with the photographs by himself and Shackleton of the coast- 

 line south of Minna Bluft' as far as Shackleton Inlet, show obvious traces of 

 waning glaciation in the shape of ice-free hills and promontories exhibiting roches 

 montonnees structure. 



Another fine piece of evidence of this kind is that supplied by Mount Hojdc at 

 the entrance of the Beardmore Glacier. Mount Hope rises 2760 feet above sea- 

 level, and fully 2000 feet above the horizon of the Beardmore Glacier Ice. The 

 summit of this great nunatak is still partly covered with moraine material, which 

 must have travelled down the Beardmore Glacier for a considerable distance. 

 Amongst the erratics, fragments of limestone, diabase, arkose, and a specimen of 

 a new type of mineral, an iron phosphide, have been found. Mount Hope itself is 

 entirely formed of granite. Like the Mawson, the Mackay, and the Ferrar Glaciers, 

 the Beardmore Glacier lies in an over-deepened valley, with a much wider valley 

 lying at an altitude of over 3000 feet above the surface of the present glacier. 

 (See Plates XXVIII. and XXIX. of Chapter V.) 



The great terraces of granitic rock with their roches montonnee surfaces, the 

 foothills near Lower Glacier Depot, between Mount Ida and Mount Hope, now ice- 

 free, were obviously produced by the glacier when its surface was fully 1000 feet 

 higher than it is now. At the foot of the Cloudmaker mountain the recent lateral 

 moraines rise to heights of fully 200 feet above the level of the adjacent glacier ice. 

 Even at the head of the Beardmore Glacier, Mounts Darwin, Buckley, and Bartlett 

 show evidence of having been enveloped in ice almost, if not quite, to their summits. 

 Here again further evidence is much to be desired as to the exact height up to 

 which undoubted traces of past glaciation extend on these mountains. (See Plates 

 XXXI. and XXXII. of Chapter V.) 



The whole of this evidence shows conclusively that the level of the outlet 

 glaciers, during the maximum glaciation or ice flood epoch, was from 2000 to 3000 

 feet higher than it is at present, while the general level of the Boss Barrier in the 

 neighbourhood of Ross Island was from 850 to 900 feet above its present level. It 

 will be seen that in this connection the question as to whether the elevated marine 

 muds of Ross Island are true " raised beaches," or upthrust portions of the sea floor, 



