H. T. Ferrar — The Antarctic Ice-cap. 



533 



The amount of snow on South Victoria Land was observed to 

 diminish in quantity as the " Discovery " steamed south along the 

 coast, and in latitude 77° South the glaciers were found to be 

 retreating. By means of graduated stakes (snow-gauges) and blocks 

 of ice exposed to the air throughout the year, it seems to be 

 established that the ablation of the ice is greater than the precipitation. 

 The mean temperature for the two Summer months was — 4-8° C, and 

 it was only when the sky became overcast and the air temperature 

 rose a degree or two above the mean that any measurable quantity 

 of snow fell. 



It is as evident to those of us who have been in high latitudes that 

 the isotherm of 0° C.^ (which is near the Antarctic Circle) is an 

 effective barrier to the transport of snow to higher latitudes ; as it is 

 evident to those who have been on both coasts of Ireland, on the 

 south coast of Africa and the Karroo, that the mountains are a shield 

 and cut off the rain from districts farther itdand. Professor Schwarz 

 uses the argument that a high temperature during maximum 

 glaciation will consequently produce more running watei', and 



Fig. 3. — The inland ice falling down between nunataks from the inland plateau. 

 From a sketch by H. T. Feixar, greatly reduced. 



attributes the deepening of glaciated valleys, not to the greater 

 power of the ice, but to that of sub-glacial streams." If this is so, 

 then the deeply incised valleys of the Royal Society Eange, with 

 their stagnant glaciers, would afford additional evidence that a rise 

 in temperature, and consequently a southerly migration of the zone 

 of maximum precipitation, had taken place at some former period. 



In his article, p. 123, Professor Schwarz says Scott found the 

 highest points to sink below the horizon directly the level ice-cap 

 was reached. Scott expressly says, on p. 414 of his narrative — 

 " when we reached the interior plateau at a height of 8,900 feet we 

 observed nunataks to the north standing above our own level." 

 Mount Lister is given as 13,000 feet high, and stands on the edge of 

 the plateau. The accompanying Fig. 3 is a sketch of the South 

 Victoria Land ice-sheet as it falls together and becomes moulded into 

 the Ferrar Glacier. The height between the graded surface of the 



1 Buchan: " Challenger " Reports, Physics and Chemistry, plates. 

 ^ Garwood: Q.J.G.S., vol. Iviii, pi. xl. 



