CHAPTER IX 



ICE-FOOT a:^d sea ice 



ICE-FOOT 



The term ice-foot as employed by us is applied to the low cliffs formed partly of 

 sea ice, partly of overlying snow-di"ift consolidated by frozen spray, which fringe the 

 coasts of the Antarctic after the breaking away of the sea ice in summer time. 

 These cliffs of the ice-foot are from a few feet up to as much as 70 to 80 feet in 

 height, their usual altitude not exceeding about 20 feet above sea-level. Their 

 existence makes landing on the Antarctic in summer time often a matter of con- 

 siderable difficulty. As will be explained in detail presently, they are formed partly 

 by a process of addition, partly by subtraction. As we followed carefully every 

 phase of their development, and took a series of photographs, it is hoped that the 

 observations will make the subject of an Antarctic ice-foot intelligible. 



It is proposed to describe the ice-foot, where specially studied by us in the 

 neighbourhood of Cape Royds, in the chronological order in which our observations 

 were made. At the time when we reached Cape Royds, at the end of January 1908, 

 the sea ice was still fast in Backdoor Bay and near Flagstaff Point. Owing to the 

 drifting action of the blizzard winds the surface of the sea ice had been covered 

 with snow, which rose in the form of a gently inclined plane from the surface of 

 the sea ice up to the tops of the low cliffs. The latter were formed of kenyte lava, 

 and at spots where they were completely levelled up by drift were from 15 to 20 

 feet high. Early in February an exceptionally high tide led to a very sudden 

 break up of the sea ice, together with the overlying snow-drifts next the shore. 

 The general appearance of the breaking up of the fast ice on this occasion is shown 

 in Fio;. 57. 



The floes in the distance next the Nimrod are covered with a thickness of about 

 6 inches of old snow. In the foreground, where not only the sea ice but the 

 snow-drift as well has been broken through, the floes consist of from 5 to 6 feet of 

 sea ice formed during the winter, capped by 7 or 8 feet of hard compressed snow. 

 This overburden of snow is sufficient to completely submerge the sea ice of the floe. 

 The following sketch indicates the structure of the sea ice at that time at Cape 

 Royds, and shows also the position of the ice-foot. 



The detachment of these small rectangular bergs, of sea ice below and compressed 



