Will Erosion Rob America Of Niagara Falls

Auckland Star, Volume LXXIII, Issue 123, 27 May 1942, Page 6

Will Erosion Rob America Of Niagara Falls

"TOO much is taken for granted on *■ this earth of ours! The pyramids have defied time for thousands of years—but what are a few thousands of years in the eons of time that have been consumed in the shaping of our earth and its physical features. To dwell a moment longer on the pyramids of Egypt— they rest on a land that was, not so long ago, geologically, the bed of a great ocean. The very limestone these pyramids are composed of was quarried from a limestone formed of tne dead shells of millions of sea creatures whose remains solidified on the sea bottom.

By A. W. B. Powell

To turn now to America's scenic wonder, the vast falls of Niagara— almost a symbol of eternity, as the visitor is prone to think. Historic records show, however, that these falls have retreated nearly a quarter of a mile in 264 years. How much longer will these falls maintain their present spectacular beauty? Will they eventually resolve into a confused mixture of raging rapids and cataracts? The answer is almost certainly in the affirmative, for that is the normal sequence of such phenomena. Nothing so drastic, however, is likely to happen in the immediate future. Nature can afford to wait. Time measured by our standards bears no relation to time in relation to eternity. The Falls Change A review of the changes resulting from erosive forces during the past 264 years do, however, show quite definitely what the first big modification of the present falls is likely to be. At present, as all know, Niagara is composed of two great falls, one in United States territory, the other Canadian, being separated by a narrow wedge-shaped piece of land known as Goat Island. For many years a far greater volume of water has been flowing over the Canadian falls, with the result that these falls have been subjected to much greater erosion than the American ones. As 95 per cent of the water now travels by way of the Canadian falls they have an approximate depth of 20ft of water at the crest, compared with a mere 31ft for the American falls. Further large-scale erosion on the Canadian side will so reduce the effectiveness of Goat Island as a division between the two falls that the whole of the river is likely to flow over the Canadian fall, leaving the American fall practically dry. The reason for the greatly accelerated erosion cf the Canadian falls is, of course, the. ever-increasing volume of water passing over it. The upper stratum over which the river flows and the spillway is formed is a very hard resistant rock, but underlying it are very soft shales and sandstones. As the under rocks weather away the undermined hard upper stratum collapses. One Big Fall? In the case of the American falls there is insufficient volume of water to clear away the debris, which thus serves to slow down further erosion of the soft under strata. The great volume of the Canadian falls, on the other hand, causes a deep plunge basin below, and all debris is swept away downstream. Thus there is no collection of rock at the base cf these falls to prevent further erosion of the soft strata. Sooner or later Goat Island, which now separates the two falls, will be completely eroded away and there will be a single wide fall stretching unbroken from American to Canadian territory. Just how long these changes will take is difficult to estimate —but that they will some day occur is evident from the fact that from the time Niagara first charged over the precipice at Uewlston and Queenston to the present the fails have receded a distance of seven miles.