REPORT OF KXECUTIVE COMMITTEE. II7 



GEOLOGY. 



T. C. Chamberlin, University of Chicago, Chicago, 111. Grant No. 

 115. For shidy of fundamental principles of geology . $6,000. 



Abstract of Report. — The main portion of the report consists of a 

 statement of the work which has been done in the critical study and 

 development of hypotheses relative to the earth's origin and its early 

 stages. As the nature of the subject is such that the work done 

 can only be definitely indicated by the results, an outline of these, 

 of measurable fullness, is given. The work has been chiefly con- 

 structive, and has consisted mainly of (i) an unsuccessful attempt to 

 develop a working hypothesis along the line of a meteoritic nebula 

 of the quasi-gaseous type, (2) a definite development of a selected 

 phase of the planetesimal hypothesis into working details, with ap- 

 plications to allied phenomena, and (3) a definite postulation of the 

 stages of the earth's growth from its origin to the earliest known geo- 

 logical stage, the Archean, on the basis of the preceding hypothesis. 



(i) The serious obstacles to the construction of a hypothesis hav- 

 ing probable conditions and working qualities on the line of a mete- 

 oritic nebula of the quasi-gaseous type are set forth. 



(2) In developing a definite phase of the planetesimal hypothesis, 

 the effort has been to bring it into contact with related phenomena 

 at so many points as to afford facilities for testing its verity, or, if 

 not that, at least its temporary working qualities, by existing knowl- 

 edge and the results of progressive investigation, and at the same 

 time to stimulate, if possible, attention to the pertinent data and 

 their significant bearings. 



(3) The hypothetical stages of the earth's growth deducible from 

 the special phase of the planetesimal hypothesis previously devel- 

 oped involve the origin of the atmosphere, of the hj'drosphere, of 

 the continental platforms and oceanic basins, of vulcanism, and of 

 the larger phases of earth deformation. The last is not, however, 

 sketched beyond its leading features, as further study is desired on an 

 important feature recently developed and not as yet duly worked out. 



The progress of the studies of collaborators is appended. 



A communication from Dr. Moulton sets forth the state of his 

 work in the critical discussion of the history of the nebular hypoth- 

 esis and other theories of the origin of the earth. 



A statement is also made by Dr. A. C. Lunn as to the progress of 

 his inquiries into the generation of internal heat by the gravitational 

 compression of the earth. 



