ON A POSSIBLE REVERSAL OF DEEP-SEA CIRCULA- 

 TION AND ITS INFLUENCE ON GEOLOGIC 

 CLIMATES.^ 



By THOMAS C. CHAMBERLIN. 

 iRead April i8, 1906.) 



Among the multitude of subjects that drew ilhiminating thought 

 from the cosmopohtan philosopher to whom we pay our homage, 

 were the phenomena of the atmosphere and the ocean. Aside from 

 atmspheric electricity, certain climatic phenomena were subjects 

 of his special study, as we are to learn more fully in the course 

 of these memorial exercises. But Benjamin Franklin was above all 

 a student of human affairs and his physical inquiries were instinct- 

 ively correlated with human interests. If, therefore, in treating a 

 phase of oceanic circulation and its bearings on geologic climates, 

 I associate my subject frankly with the interests of our race, I 

 trust it may be assigned to a desire to bring my contribution into 

 harmony with the spirit of the distinguished American philosopher 

 of the eighteenth century. 



The control of secular climates is obviously a condition pre- 

 requisite to biologic continuity. The preservation of a narrow range 

 of temperature and a limited variation of atmospheric constituents 

 throughout the millions of years of the biologic past was absolutely 

 essential to organic evolution. Continued preservation for millions 

 of years to come seems equally a condition precedent to an intel- 

 lectual and spiritual evolution commensurate with the physical and 

 biological evolutions that have preceded it. Only such a prolonged 

 evolution of the intellectuality now just dawning gives full moral 

 satisfaction to our conception of the sum-total of terrestrial history. 



The narrowness of the range to which temperatures must be 

 confined to permit progressive organic and intellectual evolution 

 takes on its true meaning only when we recall that the natural tem- 



^ Presented by permission of the President of the Carnegie Institution under 

 whose auspices these studies have been prosecuted. 



33 



PROC. AMER. PHIL, SOC, XLV. 182C, PRINTED JUNE 2$, I906. 



