GEOLOGY — CHAMBKRLIN. 171 



f 



GEOLOGY. 



FUNDAMENTAL PROBLEMS OF GEOLOGY. 



Hy T. C. Chamberlin,* 

 University of Chicago. 



I have the honor to submit herewith a report of progress on the 

 work done under Grant No. 115 during the year ending September 

 30, 1905- 



In my previous reports (Year Book No. 2, pp. 261-270, and No. 

 3, pp. 195-258) the antecedents of the present investigation were 

 set forth, together with the progress made up to the close of Septem- 

 ber, 1904. To indicate the connection of the following studies, it 

 may be recalled that investigations preceding the present series had 

 given rise to grave doubts as to the validity of the accepted origin 

 of the earth from a gaseous nebula, and hence had brought into ques- 

 tion a long line of derived doctrines that enter profoundly into the 

 current conceptions of the earth's historj'^ and of its dynamics. This 

 had made a consideration of other possible origins imperative. In 

 the report of last year the results of an inquiry into the possibilities 

 of a meteoritic origin were set forth. The results were so adverse 

 that this line of search did not seem to merit further pursuit. There 

 was also set forth in that report the results of an effort to develop a 

 working hypothesis of the origin of the earth from a spiral nebula 

 having a planetesimal constitution. This necessarily involved a 

 tentative hypothesis relative to the dynamic nature of spiral nebulae, 

 or at least of some of them, and a specific theory of their origin was 

 presented. This had for its basal assumption the simple incident of 

 one star, or other massive body, passing near another star affected by 

 eruptive protuberances, and for its basal dynamics the inference that 

 the eruptive protuberances would be intensified in mass and velocity 

 by the tidal perturbations arising from the mutual attraction of the 

 two bodies, and would hence be shot forth in both directions along the 

 line of mutual attraction. In the specific case of the solar system 

 it was postulated that, under the perturbing influence of a passing 

 star, successive masses of matter might be ejected long distances 

 from the sun, and that during their flight they would be so attracted 

 by the passing star as to assume independent orbits and thus become 

 secondaries to the sun and subject to aggregation into planets. (Year 

 Book No. 3, pp. 217-219.) 



* Grant No. 115, |6, 000. (For previous reports see Year Book No. 2, pp. 261-270, 

 and Year Book No. 3, pp. 195-258). 



