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Page:Popular Science Monthly Volume 54.djvu/372

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356
POPULAR SCIENCE MONTHLY.

GLACIAL GEOLOGY IN AMERICA.
By Prof. DANIEL S. MARTIN.

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 résumé of the whole history, progress, and scope of the study of ice phenomena 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 geological study. Professor Fairchild'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 developed 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 Silliman, 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,