November 17, 1922] 



SCIENCE 



571 



William Walden Rubet, B.A., has been 

 appointed instructor in geology by the Yale 

 Corporation, with assignment to Yale College. 



DISCUSSION AND CORRESPOND- 

 ENCE 

 THE EVOLUTION OF CLIMATES: 

 A REJOINDER 



Two articles criticising and disagreeing 

 with the writer's interpretation of the climatic 

 history of tlie earth, and Dr. F. H. Knowlton's 

 endorsement thereof, have been lately published 

 in the American Journal of Science} 



Some of these criticisms are based upon 

 misconceptions of the writer's interpretations 

 and others upon a radical difference as to the 

 source of climatic control prior to the modern 

 eva. 



In "The Evolution of Climates"^ and in pre- 

 vious publications the following theses are ad- 

 vanced : 



(1) That prior to the Modern Era, of com- 

 plete solar control, a dual control prevailed, 

 in which the heating effects of solar radiation 

 were largely intercepted by a denser and more 

 persistent mantle of clouds than has prevailed 

 since the Pleistocene; and that solar heating 

 effects were principally exercised upon and 

 above the upper surface of this cloud-sphere, 

 and were, therefore, conservative of the lesser 

 source beneath. 



(2) That wide variations in the intensity of 

 "The Solar Constant of Badiation" may have 

 occurred during geologic time, but these did 

 not directly aftect climates — for the order of 

 the distributions of temperatures and of glacia- 

 tions were not conformable to solar control. 



(3) That during geologic time earth heat 

 was made available by deformations and rup- 

 tures of the crust, etc., which from time to 

 time inaugurated activities of great heat lib- 

 erating potentiality, namely, the erosion of 

 warm erustal materials and the exposure and 

 transformation of radioactive substances. 



1 Professor A. P. Coleman (5) Vol. 1, No. 4, 

 315-319. Professor Ghas. Sohuchert, ib., 320-324. 

 This antiele is abridged from a rejoinder to 

 these eritioisms, which was denied publication in 

 that journal. 



2 Baltimore, 1922. 



(4) That upon the partial exhaustion of 

 these increments, the quickly cooling continents 

 frequently reached low temperatures and were 

 glaciated (a) in the interiors and easterly sides, 

 as least affected by ocean influences, as in 

 Huronian and Cretaeic times; (6) under belts 

 or zones of maximum anti-cyclonic circulation, 

 as in Permo-Carboniferous time; and, later, in 

 the final chill of Pleistocene time, under belts 

 of maximum cloudiness and precipitation. That 

 oceans, by reason of high specific heat, stored 

 successive increments of earth heat and fluc- 

 tuated 'between narrower limits than continents 

 until Pleistocene time, when they reached 

 glacial temperatures in polar and middle lati- 

 tudes. At this stage, they ceased to yield 

 sufficient water vapor to maintain the integrity 

 of the previous mantle of clouds in any lati- 

 tude, and the earth having lost its last available 

 increment of its original or planetary heat, 

 ceased to be a cooling body and became a warm- 

 ing body by direct exposure to and the trap- 

 ping of solar radiation converted into heat by 

 contact with the surface. That land areas fluc- 

 tuated through much wider limits or, as ap- 

 proximately fixed by Professor Schuehert, 

 from 110°" F. to —60° F., or through 170°, 

 while oceans fluctuated between 85° and 55°. 



(5) That in this process of slow and inter- 

 mittent cooling by the loss of available incre- 

 ments of earth heat, water was a circulating 

 agent of high efficiency, continuously cooling 

 land areas, and, in part, bearing the heat thus 

 derived to the oceans; the other part became 

 latent in water vapor. 



The writer does not consider the nebular 

 hypothesis as part of his interpretation of 

 geologic climates and their merging into those 

 of the Modern, Era, as indicated by Professor 

 Coleman [I. c, p. 316]. 



No glaciation is compatible with a warm 

 earth (Professor Coleman, I. c, p. 316) and 

 the writer nowhere claims that it is ; on the con- 

 trary, he holds that the earth having been 

 screened from solar radiation by clouds, its 

 continents were subject to such climatic varia- 

 tions as the available increments of earth heat 

 were competent to maintain inside the layers 

 of moist air and clouds which its warm oceans 

 were capable of sustaining. Beneath this 



