356 POPULAR SCIENCE MONTHLY. 



GLACIAL GEOLOGY IN AMEKICA. 



By Peof. DANIEL S. MAKTIN. 



UNDER this title the vice-president of Section E (Geology) of 

 the American Association — Prof. Herman L. Fairchild, of 

 the University of Rochester, New York — gave an admirable resume 

 of the whole history, progress, and scope of the study of ice phe- 

 nomena in North America, as the opening address before the section 

 at the recent Boston meeting. Apart from the interest of the subject 

 in itself considered, this address was a model of what such addresses 

 should be. While strictly scientific, without the least attempt at 

 rhetorical effect, it was at the same time so clear, so well arranged 

 and so simple in language, that any intelligent auditor could enjoy 

 it and grasp it, and carry away a distinct impression of the gradual 

 development and present status of this great department of geo- 

 logical study. Professor Eairchild's choice of his subject was happy 

 also in its fitness to the occasion, as covering almost exactly the half 

 century of the life of the association, though going back indeed a 

 few years further, into the period of the earlier society which de- 

 veloped into the association in 1848. 



The great body of phenomena comprised under the term " drift," 

 and the smoothed and scratched surfaces of rock, etc., had been by 

 no means unnoticed by the early students of American geology, but 

 they were attributed to violent and widespread water action, and 

 were spoken of in general as " diluvial " formations. "When the 

 agency of ice began to be recognized, it was regarded as that of 

 floating and stranding bergs; and this view for a long time contended 

 with the theory of glacial action, even when the latter had been 

 adopted and advocated by eminent students of the subject. 



The first allusion to drifting ice as the agent of transportation 

 of bowlders, etc., appears to have been made as early as 1825, by one 

 Peter Dobson, of Connecticut, in a letter to Prof. Benjamin Silli- 

 man, of Yale College. Sir Roderick Murchison, who became the 

 great champion of this view, credits Mr. Dobson's letter with giving 

 him the first suggestion of it. Twelve years later, in 1837, T. A. 

 Conrad made the earliest reference to land ice as the cause of our 

 drift phenomena; he does this in very striking words when read in 

 the light of the studies and determinations of later years, although of 

 course imperfectly and vaguely. 



Meanwhile, however, Agassiz and others had been working 

 among the glaciers of the Alps, and their views as to a great period 

 of former extension, in Europe and the British Isles, were finding 

 some acceptance abroad. In this country, Prof. Edward Hitchcock, 



