292 CARNEGIE INSTITUTION OF WASHINGTON. 



GEOLOGY. 



Chamberlin, T. C, University of Chicago, Chicago, Illinois. Grant No. 

 851, allotted December 13, 1912. Study of fundamental problems of 

 geology. (For previous reports see Year Books Nos. 2-11.) $4,000 



The collection and study of the climatic data of the geologic record 

 in hand at the time of the last report were continued during the early- 

 part of the year. As the assembling data took form, it became 

 increasingly apparent that the earlier geologic climates, like the later, 

 were intimately related to the distribution of land and water, and 

 hence that any true basal conception of the earth's climatology must 

 embrace the agencies that gave form to the earth's primitive con- 

 figuration. While the influence of physiographic features was thus 

 clear, it was evident also that there must have been an overmastering 

 planetary circulation of the atmosphere that persisted through all 

 influences arising from surface features and was a potent force in the 

 early climatology. It seemed advisable, therefore, to reconsider the 

 relations of surface features to the planetary circulation in the earliest 

 stages of the earth's atmospheric history and to form some estimate, 

 if possible, of the extent to which the one might have influenced the 

 other in the genetic stages. There was a special reason for doing 

 this under the planetesimal conception of the growth of the earth 

 or any analogous form of accretion, for it is evident, upon considera- 

 tion, that if the body of the earth grew to maturity by reason of the 

 accession of small bodies plunging into its atmosphere in meteoric 

 fashion, a notable portion of their substance must have been dissi- 

 pated as dust in the upper air and have found its final resting-place 

 under the conditions imposed by the atmospheric circulation. The 

 distributing and precipitating functions of the atmosphere must thus 

 have effectively influenced the lodgment of the accessory matter and 

 hence the proportionate growth of the several parts of the earth's 

 surface. The conditions of the case seem to make it clear that the 

 proportion of the planetesimal matter dissipated to dust by its plunge 

 into the air would be sufficiently large to form an appreciable factor 

 in the total growth, and that any areal differentiation in the lodg- 

 ment of this portion due to atmospheric conditions would affect the 

 growth-form of the earth as distinguished from the diastrophic form 

 imposed by internal forces. The growth-form would, further, be in 

 itself a factor in determining the phases of diastrophic action that 

 might run parallel with growth or come into action after growth 

 ceased. It thus came to appear that, under the planetesimal con- 

 ception, atmospheric action was an inevitable factor in determining 

 the surface configurations and that these in turn influenced the sub- 

 sequent atmospheric action. 



