Sir Edgeworth David 79 



eternal ice and snow was clothed with abundant vege- 

 tation. 



Equally interesting were Professor David's investiga- 

 tions concerning the depth of the Antarctic ice-cap and 

 his speculations as to the fate of the world if the South 

 Pole became warmer. Whereas most continents are sur- 

 rounded by a submerged platform one hundred fathoms 

 below sea-level, Antarctica has a platform two hundred 

 fathoms deep. This the Professor attributes to the weight 

 of the 5,000,000 square miles of Antarctic ice-cap, which 

 has depressed Antarctica the additional six hundred feet 

 below normal depth. 



He suggested that because of this the thickness of the 

 ice-cap could be measured, for the basic rock material of 

 the continent is three times as heavy as ice — therefore to 

 depress the whole of Antarctica 600 feet three super- 

 imposed layers of ice each of that thickness would be 

 necessary. Thus the average thickness of the Antarctic 

 ice-cap is approximately 1800 feet. 



The thickness of this ice-cap and the problem of whether 

 it will increase or thin out in the future are matters of 

 enormous importance to the world. The ice-cap extends 

 for 5,000,000 square miles, and represents more than one- 

 thirtieth of the whole area of the oceans of the world. It 

 can be stated, therefore, that for every thirty feet in 

 thickness of ice melted off the Antarctic continent by 

 any change in climate, the sea-level of the whole world 

 would be raised one foot, thus submerging all wharves, 

 docks, and warehouses and all tracts of country below 

 that level. 



Geological evidence shows that this danger cannot 

 entirely be dismissed. In most parts of Antarctica the 

 volume of ice is lessening rapidly, and the ice was formerly 

 at least eight hundred feet thicker than it is at present. At 

 that time the sea-level all over the world must have been 

 some twenty-five feet lower than it is to-day. Not the 



