Page:Popular Science Monthly Volume 3.djvu/299

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THE DRIFT–DEPOSITS OF THE NORTHWEST.

announced the transportation by ice of a large piece of conglomerate 4x6x8 feet a distance of 260 yards in one night. It was deposited in the sands on the shores of a little bay on the Mersey Firth.

A similar account is published in the American Journal of Science and Arts, 1822, as occurring at Salisbury, Connecticut.

After the year 1820, exact observations were stimulated in this country by the publication of the American Journal of Science and Arts, which from time to time called attention to the various phenomena of the drift. The earliest investigations of note were made by De Saussure, Pallas, and De Luc, on the Continent of Europe, and by Sir James Hall in Scotland. These observers coincided in the opinion that the existence of the "travelled rocks" must be explained by the occurrence of devastating currents of water, or débâcles, from the north, which transported them from their original places. This theory was advocated, sometimes with slight modifications, by the revered Dr. Edward Hitchcock, of Massachusetts; by Dr. Benjamin Silliman, of Connecticut; by Dr. Hildreth, of Ohio; Lapham, of Wisconsin; J. N. Nicollet, of Minnesota; and by Von Buch, Studer, Buckland, and De la Beche, of Europe. Von Buch, seeing that one débâcle, proposed by De Saussure, would not account for all the phenomena, supposed there were several. De la Beche believed this vast inundation from the north was the immediate result of a sudden upheaval of the polar regions, turning the waters of the Arctic Ocean southward with great violence. This cause was also accepted by Prof. Buckland and Dr. Silliman. This theory is the same as that known as diluvion. Hence the groovmgs on the rocks were first known as diluvial marks.

Contemporary with the débâcle theory was that of Chabrier, who believed the bowlders came from the atmosphere. This theory seems not to have met with very much countenance, and soon ceased to be regarded.

In 1828 Peter Dobson, of Connecticut, proposed the germ of what became an important and long-lived theory, viz., that floating ice, in the form of vast sheets, carried great quantities of gravel and stones, and distributed them wherever they were stranded. This suggestion, aided by the quick indorsement of Sir R. I. Murchison, grew into that known as the iceberg theory, which survives to the present day. This last necessitates the submergence of the continent beneath the quiet waters of the ocean, and here diverges from the débâcle theory which requires turbulent waters. The iceberg theory received many prominent and able advocates. Among them may be named Sir Charles Lyell, Sir Roderick I. Murchison, Peter Dobson, John L. Hays, C. T. Jackson, Sedgwick, of England; W. C. Redfield, of New England; Prof. Mather, of Ohio; Dawson, of Canada; and a great many others.

Before, however, the iceberg theory had grown into prominence, Mr. De Kay, of New York, proposed another, which at least has the