CONDITIONS OF CONTINENTAL ICE. 223 



point would soon be reached where the ice could no 

 longer retain the solid form. If, for example, owing 

 to the heat of the climate, we could not have ice at a 

 lower temperature than say 30°, then a glacier over 1 

 mile in thickness would be an impossibility, for the 

 bottom of a glacier of greater thickness would not 

 remain solid at that temperature. 



Having considered the various circumstances affecting 

 the temperature of the Antarctic ice, and the sources 

 from which it derives its heat, we have found that 

 the temperature of the ice must be considerably under 

 the freezing-point. We are now prepared to examine 

 the reasons which have been adduced for concluding 

 that about 1400 feet is the probable limit to the 

 thickness of the Antarctic ice-sheet. 



