640 



SCIENCE 



[N. S. Vol. XLVI. No. 1200 



This observation applies to an iee-eovered 

 area of over 116,000 square miles. 



Mr. Griffith Taylor notes the recession of 

 Dry Valley Glacier twenty miles from the sea 

 below Taylor Glacier.'' 



Mr. Taylor also notes and speaks with con- 

 fidence of the passage of the Ice Age from 

 Antarctica.* 



In speaking of the evidence of ice retreat 

 over Antarctic areas explored by him, Sir 

 Ernest Shackleton said: 



Some time in the future these lands will be of 

 use to humanity.9 



This impressive and conclusive evidence is 

 corroborated by the greater and still more im- 

 pressive evidences of the comparatively recent 

 uncovering of temperate land areas,^" and the 

 progressive retreat of the snow line to higher 

 elevations in temperate and tropical latitudes 

 and towards the poles at sea level, being far 

 greater in Arctic than in Antarctic regions. 

 We are therefore confronted with the con- 

 clusions : 



1. That the disappearance of the lee Age is 

 an active present process and must be ac- 

 counted for by activities and energies now at 

 work, and that the use of assumptions and 

 hypotheses is not permissible; 



2. That the rates and lines of retreat are 

 and have been determined by exposure to 

 solar energy and the temperatures established 

 thereby; and by the difference in the specific 

 heat of the land and water hemispheres; 



3. That the lines of the disappearance of 

 ice are not conformable with those of its dep- 

 osition, and mark a distinctly different ex- 



TJ&., p. 286. 



8J6., p. 288. See also photograph following p. 

 286 and p. 292. 



8 Address to the Commonwealth Club, San Fran- 

 cisco, Calif., November 7, 1916. 



10 Slight fluctuations in the retreat of the small 

 residual glaciers in temperate latitudes are noted 

 in the reports of the Commission on Glaciers 

 of the International Geological Congress by 

 Professor Harry Fielding Eeid. But the great 

 measures of the progressiveness of glacial retreat 

 are in the past disappearance of the Pleistocene 

 ice fields of temperate latitudes and the present 

 retreat in the Antarctic and Arctic regions. 



posure and climatic control from that which 

 prevailed prior to the culmination of the Ice 

 Age. 



4. This retreat also marks a rise in mean 

 surface temperature along these new lines, 

 manifestly due to recently inaugurated ex- 

 posure to solar radiation and also the inaugu- 

 ration of the trapping of heat derived from 

 such exposure; which process is cumulative 

 and has a maximum not yet reached. 



The researches under the direction of Cap- 

 tain Scott and Sir Ernest Shackleton have 

 therefore very rigidly conditioned any inquiry 

 as to the causes of glacial accumulation and 

 retreat. These conditions are corrective and 

 DIRECTIVE — corrective, in that they have en- 

 tirely removed any doubts as to the alternate 

 glaciation of the poles under the alternate 

 occurrence of aphelion and perihelion polar 

 winters by the precession of the equinoxes, as 

 advanced by Croll; directive, in that they 

 have imposed an appeal to energies now active 

 as causes of retreat, and divested the problem 

 of resorts to the fascinating but dangerous 

 uses of suppositions and hypotheses. 



They have, moreover, pointed out with un- 

 erring accuracy the vital conclusion that the 

 same energies which have but recently con- 

 verted the glacial lake beds of Canada into 

 the most productive grain fields of the world 

 will in time convert the tundras of to-day 

 into the grain fields of to-morrow.^^ 



The bearing of this conclusion upon the 

 ultimate development of the human race is 

 so far-reaching in its consequences that the 

 great sacrifice of life attendant upon the 

 prosecution of these researches stands forever 

 as a memorial in the correction of the erro- 

 neous and wide spread conception that the 

 earth is in a period of refrigeration, desic- 

 cation and decay; and establishes the con- 

 clusion that it is in the spring time of a new 

 climatic control during which the areas fitted 

 for man's uses are being extended and that 

 the moss of polar wastes will be replaced by 

 rye and wheat. Maesden Manson 



San Francisco, California 



11 See also Compte Rendu da Xli&me Congrgg 

 Ggologique International, p. 1102. Stockholm, 

 1910. 



