Page:The New International Encyclopædia 1st ed. v. 14.djvu/620

* NIAGARA RIVER AND FALLS. 528 NIAGARA RIVER AND FALLS. projects like a shelf over the edge of the falls so that the water leaps from it and strikes the surface of the pool below. Xow and then large blocks of the upper limestone break away and fall into the pool, due doubtless to the erosion of the softer shale beneath, the limestone thus being deprived of its support. .Just how the shale is eroded, and how the harder rock beneath it is atfeeted. is in doubt. It is observed in the Cave of the Winds, where visitors may pass behind one of the thinner segments of the falls, that spray and water are constantly dashing against the shale and probably wear it away. The shale is also calcareous, and this element in it being soluble, it is likely that solution has a part in the work of destruction. As the water contains no sediment, the Niagara Kivcr cannot use this agency, as most rivers do, to scour out its bed; but tile broken pieces of rock that fall into the river below the cataract are undoubtedly [)otent in iligging out and deepening the channel. Oov- erinncnt engineers have discovered de|>ths of 200 feet a half mile below the falls, and (Mlbert and other geologists assume that the falls are scouring the river bed as deeply now as they did when they were situated farther down the stream. This is occurring in front of the Horse- shoe Falls, but not at the American Kails, where the volume of water is comparatively small. The broken rock here piles up as a talus at the foot of the fall, and u])on it the force of the descending water is spent. The edge of the American Falls is retreating much less rapidly than that of the Horseshoe Falls. The average annual recession on the Amer- ican side has been only about a halt foot for the past fifty years; but the Horseshoe Falls have receded in fifty-two years from 1.50 to 2.S0 feet along the western half of its edge, and 270 feet at the apex of its curve, making a recession of from four to six feet a year. If this rate of recession were constant, the proof would be con- clusive that the gorge, from the Niagara escarp- ment to the falls of today, had been excavated in about 7000 years. But the thickness of the resistant bed at the crest of the falls is far from uniform : and there is evidence that at one period after the retreat of the ice the upper lakes founil outlets through other rivers, and only l,ake F.rie was drained by the Niagara, whose small volume of wati'r then must liave been greatly inferior to that of to-day in its ability to excavate the gorge. The assured fact is that the gorge is gradually being cut back toward Lake F^rie. About a half mile above the brink of the falls, (ioat Island divides the river into two une<|Ual streams, the one on the .American si7 feet. The Horseshoe Falls have a total width of .'iOlO feet, measured along the curve, or 1230 across the chord, a maximum estimated depth of 20 feet, and a vertical height of l.iS feet. .As the water 13 derived from the immense reservoirs of the lakes, there is little variation in the ijuantity, the dill'erences in volume depending not so much ujion precipitation as upon the strong winds which slightly retard or accelerate the movement of the surface waters of Lake Erie to the mouth of the river. The normal How pouring over the cataract is about 500.000 tons a minute. The falls, being one of the great scenic attrac- tions of the world, are visited every year by many thousands of tourists. From the time when Father Hennepin discovered them in lli78. and wildly estimated that they were over 500 feet in height, they have never been adequately de- scribed. A realizing sense of the grandeur of this prodigious green flood pouring into an abyss where it is half lost in the masses of ascending mist can be obtained only by personal observa- tion. Sightseeing has been greatly facilitated, and visitors protected from imposition since 1885, by the conversion of the land on both sides of the falls into public parks. The New York State Reservation contains 107 acres, and the Queen Victoria Niagara Falls Park on the Canadian side 154 acres. Since these banks became Gov- ernment properties, the mean industrial struc- tures that marred them have been torn down, and the wonilerful spectacle may now be enjoyed at leisure from shady avenues, artificial ]>lat- forms, and other advant.ageous points of view. Trains on the Canadian side wait for a few minutes to give the passengers a glimpse of the vast sheet of water curving over the Horseshoe Falls. An electric trolley line has been built through the gorge along the brink of the river on the American side and connects by the (Jueeiis- town Ijridge with the electric line skirting the Canadian lieights along the gorge and extending past the Horseshoe Falls to Chijipawa; a railroad also skirts the United States edge of the gorge, so that visitors may see its entire length and take in the terrific features of the rapids and the whirlpool. JIany visitors enter the Cave of the Winds, approach the falls on the steamer Maid of the Mist, or enjoy the superb general view from the middle of the upper arch bridge or the high terrace below the Horseshoe Falls on the Canadian side. Several days are re- (juired even for a cursory exaniiiiat ion of all the attractions of the place. The bridge thrown across the river a little below the falls was long regarded as a wonder of engineering. This sus- pension bridge for pedestrians and carriages, built of steel about 250 yards below the .American Falls, had a span of 821 feet. It has been re- placed by an arch bridge. The cantilever. HIO feet long, spanning the gorge some distance above the Whirljiool, was the lirst briilge of the kind to be built in .America; the railroad steel arch bridge, 300 feet below the cantilever, has a car- riageway below the track. It is only in recent years that important attempts have been made to utilize the encrgv" of Niagara Falls for industrial purposes. The largest plant is that of a power company which generates electricity by leading water through a canal from above the falls to a wheel ]iil in which are turbines, the water discharging through a tunnel into the river below the falls. >Iany in- dustries at the falls are using the electricity, and Buffalo, 22 miles distant, takes it for its city railroads and other power purposes. Over three-fourths of the power generated, however, is consumed in the neighborhood of the falls.