256 POPULAR SCIENCE MONTHLY. 



the known facts and to discuss them along the lines so successfully fol- 

 lowed in reference to Pleistocene glaciation. An important difference 

 in the argument as applied to the two cases lies in the cause assigned 

 for depletion of the atmospheric carbon dioxide. The postulate of an 

 appropriate time relation between Paleozoic land movements and the 

 epoch of glaciation being conservatively assigned a minor position, the 

 storage of carbon as coal is given major rank in accordance with known 

 relations. This process is not attended by the accelerating and react- 

 ing influences, which are due to the equivalent of carbon dioxide con- 

 tained in bicarbonates, and glaciation would, therefore, result only after 

 depletion had continued longer. In this suggestion is found a possible 

 reason for the wide extension of cool climate and the occurrence of 

 glaciation in remarkably low latitudes. 



The broad scope of philosophic thought upon which this working 

 hypothesis rests is indicated by the titles of articles which have 

 flowed from Chamberlin's pen in the last four years.* Fortifying his 

 own general researches where needed by those of specialists, he, with 

 reason, challenges fundamental and generally accepted views. He gives 

 the geologist and biologist new clues with which to thread the labyrinth 

 of knowledge, and develops important relations between djmamical 

 geology, stratigraphy, climate and evolution. 



* A Group of Hypotheses bearing on Climatic Changes, Jour. Geol., Vol. V., 

 No. 7, 1897. The Ulterior Basis of Time Divisions and the Classification of 

 Geologic History, ibid.. Vol. VI., No. 5, 1898. A Systematic Source of Evolution 

 of Provincial Faunas, ibid.. No. 6, 1898. The Influence of Great Epochs of 

 Limestone Formation upon the Constitution of the Atmosphere, ibid. Lord 

 Kelvin's Address on the Age of the Earth as an Abode Fitted for Life, Science, 

 N. S., Vol. IX., No. 235, pp. 889-901, Jime 30, 1899, and Vol. X., No. 236, pp. 

 11-18, July 7, 1899. 



