THE ROSS BARRIER l;i7 



can trace distinctly the individual ice ribs, belonging respectively to the Reeves 

 Glacier, the Larsen Glacier, and the David Glacier,* so in the case of the Ross 

 Barrier one can probably recognise the traces of "the Bluff rib" derived from the 

 stemmed and deflected ice of the Barne Inlet and other glaciers, from the mountains 

 to the south-vrest of the Ross Barrier as well as the eastern ice ribs, perhaps derived 

 from the coalescence of the Beardmore Glacier ice with that of glaciers farther to 

 the south-east and east. While it is thus assumed that the higher parts of the 

 Barrier represent fauned-out glacier ribs, the low-lying parts of the Ross Barrier 

 can be explained in at least three, possibly four, ways, as follows : — 



First, they may be due to the fans, or ribs, of the respective piedmonts afloat, 

 contributing to form the Barrier, becoming very thin at their edges, as a consequence 

 of prolonged S23reading and consequent thinning of the ice as it progressively fans 

 out wider and wider as it advances seawards. 



Secondly, these low areas may mark more or less radial strips along the Barrier 

 where the edges of individual floating glacier fans fall short of each other, and so 

 fail to coalesce, the stretches of sea between becoming built over with bay ice, 

 lasting for many seasons, its surface receiving annual additions of drift or new- 

 falling snow. This is obviously the case with much of the Drygalski-Reeves 

 Piedmont. 



Thirdly, the low parts alternating with high may be due, and no doubt are in 

 part due, to the existence of considerable undulations in the surface of the Barrier, 

 particularly in the neighbourhood of the Bay of Whales and the Western Inlet. 

 As already stated, Scott recoi'ded that near Balloon Bight these long and wide 

 undulations, trending nearly east and west, had a depth of 120 feet. As the 

 greatest height of the Barrier cliff is usually about 150 feet, it is obvious that, if 

 by the breaking away of bergs from the Barrier face the bottom of one of these 

 troughs were exposed to view, the height of the cliff wall there would not exceed 

 about 30 feet. The existence of Western Inlet in the Barrier 100 miles west of the 

 Bay of Whales is, perhaps, to be explained as the result of differential marine 

 erosion of a corrugated ice sheet, the sea eating back the thinner ice of the troughs 

 more quickly than the thicker ice of the flat-tojjped ridges. 



Fourthly, it is by no means improbable that there is differential etching of the 

 under surface of the Ross Barrier through the solvent action of water coming 

 upwards from a depth, the temperature of such water being slightly in excess of 

 that of the general temperature of the surface water. Reference has already been 

 made to the influence of shoals in deflecting upwards these relatively warmer waters, 

 and so keeping pools of sea water open, almost all the winter, on the lee side of such 

 shoals in regard to the prevalent ocean currents. Comment has already been made 

 on Ross' discovery of warmer water at a depth in Ross Sea, and this conclusion has 

 been abundantly confirmed by subsequent scientific expeditions. There can be no 

 * To these must now be added the Campbell, Priestley, and Corner Glaciers. 



