82 
H. T. FERRAR. 
summer suu to get through, and the ice beneath it may then be preserved 
almost indefinitely. 
The characteristic sheer ice-walls bounding the glaciers of South Victoria Land 
show that under present conditions the sides are receding from the land. The interven- 
ing channels often contain frozen ponds, which in some cases, though only 50 yards 
broad, are more than a mile in length. The large pond at the base of Knob 
Head may be contrasted with the Marjelen See, in that it follows the straight 
side of the main valley instead of merely occupying the dammed-up end of a 
tributary valley (Fig. 41, p. 76). 
The structure of the ice between the bands of intra-glacial material at the 
base of Knob Head shows remarkable variations. The uppermost 40 feet appears to 
be quite normal vesicular glacier-ice and is free from rock -debris (Fig. 42, p. 77). 
Below this are several notable dirt-bands, and among them other bands from 
2 to 10 feet thick, perfectly clean, and clear as rock-crystal. On melting small 
fragments from these bands no granular structure could be seen, and it is 
suggested that they are, in part at least, due to intrusive thaw-water. Other 
bands showed air-vesicles elongated at right angles to the banding. The ice 
o o o o 
which contains the majority of boulders has a structure comparable to that of 
ordinary rock-fault breccias, and it would appear that the ice here glides forward 
as a series of rigid sheets along parallel thrust-planes. 
Up-thrust of morainic material similar to the up-thrust in Spitzbergen described by 
Professor Garwood,* was also observed at Depot Nunatak, where Beacon Sandstone 
boulders are brought up to the surface. Up-thrust was again in evidence behind the 
Solitary Rocks on the Ferrar Glacier. Up-thrust produced by impact of two streams of 
ice is further seen at the foot of Knob Head, where the dirt-bands with large boulders 
bend up and appear on the surface 70 feet above their usual position (Fig. 41, p. 76). 
Tee-movement . — Owing to the great distance which separated Winter Quarters 
from any glacier, our observations on the rate of ice-movement have been few 
in number. The rate at which the ice from South Arm forces its way into 
East Fork of the Ferrar Glacier is probably less than six feet per month. Other 
observations made at its snout indicate that the rate is extremely small. The Blue 
Glacier moves less than four feet a year, while the Ross Piedmont, as measured by 
Lieutenant Barne from the depot off Minna Bluff, moved no less than 608 yards 
in 13 J months. The movement of Ferrar Glacier or Blue Glacier causes little 
disturbance of the sea-ice ; slight movements are transmitted to the latter and 
become lost in its more ordinary movement. Where the Ross Piedmont abuts 
against Mount Terror, three parallel and well-defined ridges appear. These are at 
least 50 miles long and usually some 50 feet high. They have been traced by 
Lieutenant Royds towards the north end of White Island, but gradually flatten out 
and fan. At Pram Point four lines of parallel hummocks, each about 15 feet high, 
* Garwood and Gregory, Quart. Journ. Geol, Soc., 1898, vol. liv, p. 219. 
