Recession of Niagara Falls in 133 Years

Abstract

THE fallacy of Lyell's guess at the rate of recession was always plain if we referred to the first accurate account, that of the Swedish traveller Kalm, in Gent. Mag., January, 1751; since which the gorge has both been enlarged full 100 acres, and had miles of its bed deepened many feet. In p. 16, col. 1, A, he said: “Canoes can go yet half a league above the beginning of the carrying place, … but higher up it is quite impossible, the whole course of the water, for two leagues and a half up to the great fall, being a series of smaller falls, one under another.” Now plainly this whole series have so levelled their bed that the main falls now descend some 160 feet instead of the “137 feet” that he repeatedly maintained (col. 2, E) to be the utmost the engineers, “with mathematical instruments,” then admitted. But as for the plan, he is yet more definite. P. 16, col. 1, E: “The river (or rather strait) runs here from south-south-east to north-north-west, and the rock of the great fall crosses it, not in a right line, but forming almost the figure of a semicircle or horse-shoe.” (Prof. Tyndall has well remarked that, the upper stream having probably been always much wider than the gorge, the chief fall has always been concave; but Kalm's view makes it appear very slightly so, and we know that very flat segments are, by a perspective illusion, commonly thought semicircles or even “horse-shoes.”) “Above the fall, in the middle of the river, is an island, lying also south-south-east and north-north-west, or parallel with the sides of the river; its length is about 7 or 8 French arpents (an arpent being 120 feet). The lower end of this island is just at the perpendicular edge of the fall.” He proceeds to tell how this island, once thought inaccessible, had been the scene of the heroic rescue, twelve years before, of two Indians by two others. Then, p. 18, col. 2, F.: “The breadth of the fall, as it runs in a semicircle, is reckoned to be about 6 arpents. The island is in the middle of the fall, and from it to each side is almost the same breadth” (barely 350 feet then, but in his engraving not half that). “The breadth of the island at its lower end is two-thirds of an arpent or thereabouts.” His view makes it but one-third the height, i.e., one-third of “137 feet.”