Page:Popular Science Monthly Volume 20.djvu/247

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235
NORTH AMERICA IN THE ICE PERIOD.

Packard describes glacial markings in the Hamilton Inlet fiord running to the northeast, and thinks that the movement was to the southeast on the southern coast, or toward Newfoundland.

Farther north, the Meta incognita just north of Hudson's Straits shows an extensive mer de glace, with southerly-moving glaciers. McClintock describes bowlders at Leopold Harbor (North Somerset) and at Graham Moore Bay (Bathurst Island), which have been transported one hundred and one hundred and ninety miles northeast and northwest. Glaciated conditions are mentioned by various explorers to the west of Hudson's Bay, but we have no facts to indicate the direction of the movement. Several statements made in Franklin's second voyage imply a westerly movement.

There is a marked difference in the distances to which bowlders hsve been transported by the southwest and southeast currents. The average distance of the transportation in New England is from twelve to fifteen miles, and no bowlders, so far as known, have been carried more than one hundred miles. At the extreme north edge of Maine, as well as near the north line of Vermont, west of the Connecticut water-shed, are a few bowlders that have come from beyond the St. Lawrence, thus indicating a southeast movement across the St. Lawrence Valley, at right angles to what is supposed to be the common course. In Ohio many stones have been transported more than one hundred miles. In Iowa and Wisconsin bowlders of native copper occur from three hundred to four hundred and sixty-five miles away from their supposed source in Michigan. From the Lake of the Woods G. M. Dawson has described a transportation toward the Rocky Mountains of seven hundred miles. At Baton Rouge, Louisiana, are fossils, perhaps transported by floating ice, that seem to have come from Canada West, as much as twelve hundred miles; and at Natchez, Mississippi, there has been found auriferous quartz, supposed to have come from Montana, eighteen hundred miles. The southwest direction has therefore afforded the examples of the greatest distance traveled by the bowlders. Perhaps topography has aided the result, and the St. Lawrence valley is directly continuous with the Western prairies and Mississippi bottoms, and the New England mountains have intercepted the material brought from the Laurentian highlands.

The evidence is clear, however, of the passage of the ice-sheet directly over all the higher New England summits in a southeasterly direction. The facts illustrative have been specifically given for the Green Mountains, as Mounts Mansfield, Camel's Hump, Pico, Eolus, etc.; for Grey lock, the highest of the Massachusetts mountains; for Mount Washington, and others of the White Mountains, in New Hampshire; and for Katahdin, in Maine, in the several geological reports of those States. The most important case is that of Mount Washington, both because of its greater altitude and because it has been generally supposed to have been an exception to the rule, and most geologists