332 POLAR PROBLEMS 



climate, which, so far as the paleobotanical record can be rehed upon, 

 may have included the entire earth in one salubrious whole. 



In Cretaceous times, again, there is clear indication of a temperate 

 to warm-temperate climate in West Antarctica, and it is not until 

 the close of this age that the first evidence of local refrigeration is 

 found. Then followed a regional cooling which was to usher in one 

 of the world's greatest glacial episodes, giving birth, after some set- 

 backs, to immense ice floods. These today, in the Antarctic and in 

 Greenland, remain the only parallel to the American and European 

 ice sheets of the Pleistocene, which were of vital importance in the 

 evolution of man and still are of the greatest interest. 



Remains of dicotyledonous trees, including beech leaves, from 

 Graham Land bear eloquent testimony to the fact that this great 

 cooling took place, as appears always to have been the case, in a 

 series of great pulsations. Evidence of several such gigantic pulses 

 with ebb and flow of the ice floods is clearly seen both in East and 

 West Antarctica, the pendulum swings culminating in a continental 

 ice sheet a thousand and more feet thicker than that of the present 

 day. Today the ice sheets are steadily receding; and we do not know 

 why. It is possible that the phenomenon may be caused — as was first 

 suggested by Captain Scott — by the very severity of the Antarctic 

 climate itself, causing starvation at the center of the anticyclone and 

 the development of a steepened temperature gradient at its periphery, 

 with enhancement of the outward-blowing hurricanes laden with 

 drift from the coastal valleys and the interior. 



This is only one of the manifold problems of polar glaciology which 

 require for their solution the development of polar meteorology on a 

 scale far transcending that attempted up to date. 



Expedition after expedition has reported bare slopes where ice- 

 swathed contours ruled in the times of its immediate predecessors. 

 Ice-bound peninsulas have become islands in a very few years. Con- 

 troversies between generations of polar surveyors are a witness 

 not necessarily to the ignorance or lack of precision of the preceding 

 generation but often to the steady retreat of the coastal ice. One 

 of the problems of the future explorer will be to keep track of this 

 continuous, though jerky, recession; one of his difficulties, to resist 

 the tendency to attribute visible changes to the inefficiency of his 

 predecessors (sometimes, alas, justified) rather than to a natural 

 process of which evidence is steadily accumulating. It is not enough 

 to make a single survey of lands inundated by ice. Their contour 

 and outline are ever changing. Constant attention to such detail, 

 combined with the careful recording of every factor, large and small, 

 of the environment in which the ice forms exist, will, in the long 

 run, render it possible to make the generalizations which are so 

 fascinating but which the present generation of explorers should avoid. 



