114 GLACIOLOGY 



the farthest point north along the coast visited by us, just beyond Horseshoe Bay, 

 we found several foreign erratics, including many pieces of undoubted Beacon 

 Sandstone. 



We now pass on to Cape Bird. The photographs of Plate XXVII. show the 

 general appearance of this cape near the point where Macintosh and McGillan 

 landed previous to their sensational trip overland to Cape Royds. In picking 

 up tlieir depot and tent Mawson obtained a series of specimens of rocks from 

 tlie shore-line. The dominant rock was later described by Jensen. These rocks 

 w«re mostly erratics composed of trachytes, of strongly alkaline kulaites or trachy- 

 doleritic rocks, sub-alkaline basalts and dolerites, some enstatite-bearine:, some 

 olivine-beariug. Erratics foreign to Ross Island were not observed. 



In the upper figure it will be noticed that there is a well-marked terrace, 

 suggestive either of its being a raised beach or a parallel road. It is very similar 

 to the feature observed along the east coast of Backdoor Bay, and ajipears to be a 

 similar height above sea-level. The height of the Backdoor Bay terrace was about 

 50 feet. It will be seen that the glacier, mantling around the parasitic volcanic 

 cone in Fig. 1, does not reach sea-level. In Fig. 2 a small parasitic cone is shown 

 immediately over the boat. The absence of foreign erratics, as far as we could judge 

 at Cape Bii-d, is probably to be explained by the slight westerly deflection imparted 

 to the Ross Barrier by the pressure of the ice descending the west slopes of Erebus. 

 This would of course tend to push the great marginal moraines of erratics, foreign 

 to Ross Island, away to sea at some littlfr^distance from the coast, before the Ross 

 Barrier reached Cape Bird. Cape Bird proper is 25 miles distant, in a north by 

 east direction, from Cape Royds. The spot from which Mawson collected the erratics 

 described by Dr. Jensen was approximately 10 miles south by west from the cape, 

 and almost opposite to Mount Bird. 



SUMMARY OF THE FERRAR GLACIER AND CAPE 



ROYDS REGION 



We are now in a position to review briefly the structure of the inland ice and 

 glacier ice, past and present, between Scott's farthest west, on his western journey, 

 and the moraines of the western foothills of Erebus abounding in erratics foreign 

 to Ross Island. The same features so conspicuous on the section from the South 

 Magnetic Pole area to the Drygalski Ice Barrier Tongue are repeated. On the left 

 and west is a high plateau, rock-free, and covered no doubt to a considerable depth 

 by the inland ice sheet. Its level is singularly uniform, varying from a little over 

 7200 feet to about 7550 feet. This remarkable uniformity of level is maintained 

 for no less a distance than 110 miles. 



Next, eastwards, one reaches the great horst. This rises at first in the Lashley 

 Mountains to an altitude of 8590 feet ; still farther east, in Mount Davis, to 9000 



