THE ROSS BARRIER 135 



Robertson's Bay. During the maximum glaciation the coalesced ice streams formed 

 a vast piedmont aground, just as, at the same epoch, did the Drygalski, Reeves, 

 Campbell, Corner, and Priestley Glaciers of the Drygalski-Reeves Piedmont. Then, 

 as the glaciers shrunk with diminution of the snow suj^plies, the piedmont floated up 

 and retreated southwards, as Scott has sujaposed. Meanwhile the surface of this 

 floating jjiedmont would form a receptacle like a vast shovel, or fork with much 

 widened prongs, for snow falling on its surface, or drifted off" the high jjlateaux 

 which bound the Barrier region on the south-west, and the lower plateaux on 

 the south-east from King Edward VII. Land to Carmen Land. Little by little, as 

 the glacier ice towards the central and northern portions of the Ross Barrier became 

 melted oft' from beneath, neve, passing into ice at a depth, would gradually take 

 its place. This neve would result from the accumulation of superficial snow 

 deposits. 



The observations of Macintosh and Day show that the snow which actually falls, 

 or is drifted, on to the Barrier surface, must be an important contributor to its 

 volume. A great deal of the Barrier extends southwards from its terminal face on 

 Ross Sea, for a distance of fully 300 miles (483 kilometres), and even over 500 miles 

 (805 kilometres) in the case of the Devil's Glacier. The Beardmore Glacier, for 

 example, at its lower end, where it joins the Barrier, is 350 miles (563 kilometres) 

 distant from the Barrier face. It may be assumed that the annual amount of 

 compressed snow contributed to the western portion of the Barrier surface, as the 

 result of additions from drift snow as well as from actual precipitation, is about 

 1 foot ('3048 metre). From the observations of Scott and Macintosh of the rate 

 of movement of the Barrier near Minna Bluff", it may be inferred that the Barrier 

 is travelling seawards at the I'ate of about 492 yards (450 metres) per year. From 

 this one may argue that snow falling on the foot of the Beardmore Glacier, 350 miles 

 inland, would take 1252 years to reach the edge of the Barrier where bergs dis- 

 charge into the sea. At this rate, if 1 foot of snow * is added to the Barrier 

 every year, ice from the Beardmore Glacier, which left the foothills about 1250 

 years ago, if it reaches the Barrier cliffs at the present day, will be covered by a 

 thickness of about 1250 feet of snow, without allowing for the compression of the 

 lower layers into ice. Obviously, this theory gives a considerable thickness of snow 

 to form the seaward end of the Ross Barrier. That the under jaart of the Barrier, 

 except, perhaps, near its centre, is still formed of glacier ice, is suggested as beino- 

 possible by the nature of its cross-section from east to west. 



This section is based almost entirely on the soundings and altitudes given by 

 the British National Antarctic Expedition of 1901-4 along the face of the Ross 

 Barrier. Reference to this section and to the plan of the Barrier shows that the 



* This estimate of an annual addition of 1 foot (-3048 metre) of hard compressed snow, equal to 

 about 75 inches (-19 metre) to the Barrier surface, applies only to the Minna Bluff region, as far as 

 the very limited observations up to the present extend, and is not necessarily of wide application. 



