Page:Popular Science Monthly Volume 12.djvu/335

Rh to the ocean, reaching its maximum in Maine and the borders of Canada; while, as we retire from the margin of the States, we observe that the scratches and grooves acquire a north-and-south direction, becoming nearly meridional over New York, and then slowly swing round to the west, until in Ohio, Indiana, Illinois, Missouri, and the western limits of the continent, they lie pointing northeast and southwest. Thus they assume a rudely-outlined radiation from the highlands of Canada, and stretch out from an hypothetical centre there like the multiplied spokes of a great wheel. In Switzerland they sweep down and out from the central ranges of the Alps in all directions, and, while locally uniform, they converge from the south, and east, and north, and west, toward the lofty slopes and pinnacles of this congeries of mountains. Over West Russia and Northern Europe, where the markings are discovered, they indicate the Scandinavian mountains to have been the seat of whatever disturbance or agency has, at a distant period, fluted and engraved the continent; similarly, as the rocks lie related to the Highlands of Scotland, the Lake Hills of England, or the mountains of Wales, the striæ impressed upon them extend toward every point of the compass. They stream north and south from the summits of the Pyrenees, from the peaks of the Caucasus, and down the valleys of the Himalayas. It must be understood, however, that these conclusions are based upon an average of the bearings of the grooves in each instance, and that these are infinitely varied by the construction and irregularity of the land.

Thus over greater portions of the world we find the rocks furrowed, polished, and striated, in long, frequently deep and rectilinear grooves, which lie in groups and series identical in direction, and pointing to associated highlands, or distant continental mountain ranges, as the source of whatever strange and inexorable instrumentalities have produced them. Over New York Island the gneissoid and granitic rocks, where they raise their tilted strata and broken shoulders above the ground, are scored frequently with deep and sinuous channels. In Central Park, along Fifty-ninth Street, up the west side, the contorted and twisted humps of gneiss are moulded in this way. Sometimes, where a rupture exists, and one part of an outcrop has fallen below the other, the grooves are continued on the lower half; frequently the lines are crowded together like rulings on a page, and again the groove is of irregular depth, its floor rising and falling as though hitches had occurred when it was first planed, the great chisel meeting resistance, or being thrown up at points along its path. In the White Mountains the sides of the mountains, the valleys, the top of Mount Washington, at 5,000 feet above the sea, are all cut with these strange furrows, the rocks polished, and the whole country bearing these evidences of past erosion wherever the naked rock meets the eye. Over Maine the same phenomena present themselves in endless succession, the grooves striping