THE 



JOURNAL OF GEOLOGY 



JULY-AUGUST, 1906 



ON A POSSIBLE REVERSAL OF DEEP-SEA CIRCULATION 

 AND ITS INFLUENCE ON GEOLOGIC CLIMATES^ 



T. C. CHAMBERLIN 



University of Chicago 



The control of secular climates is obviously a condition prere- 

 quisite 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 intellec- 

 tual 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 con- 

 fined to permit progressive organic and intellectual evolution takes 

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

 ture range on the earth's surface is sixteen times as great as this, 

 while that affecting the solar family is at least sixty times as great. 

 For a hundred million years, more or less, this narrow range of 

 temperature has been maintained quite without break of continuity, 

 unless geologists and biologists are altogether in error in their induc- 

 tions. On the further maintenance of this continuity hang future 

 interests of transcendent moment. 



I Published by permission of the President of the Carnegie Institution, under 

 whose auspices these studies have been prosecuted. Read, with unimportant aherations 

 before the American Philosophical Society at the FrankHn Bicentennial Celebration. 

 Vol. XIV, No. 5 363 



