Page:Popular Science Monthly Volume 49.djvu/20

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8
THE POPULAR SCIENCE MONTHLY.

of the modern river in the region of the falls themselves, but this is a mile and a half wide. Its section is shown beneath the drift in Fig. 8.

Indeed, there was no ancient outlet of the Erie basin in the vicinity of Niagara River, but the ancient drainage course was

PSM V49 D020 Sectional view of the gorge at two different points.jpg
Fig. 6. — Section across the Narrows just North of the Railway Bridges {dd Fig. 9). b, Original bank of the river; r, surface of the river; L O, level of lake; floor of cañon eighty feet below lake level. Fig. 7. — Section Half a Mile from the End of the Cañon (gg, Fig. 9). bb, Terraces of river at the original level; L O, level of Lake Ontario; bottom of river about eighty feet below the surface of Lake Ontario.

discovered about fifteen years ago to have been some forty miles farther west, where is now the buried channel of the ancient Erigan River, terminating in the extreme western end of Lake Ontario. Thus the necessity of a preglacial Niagara River was removed.

To describe the features of the Niagara River more accurately, so as to interest special readers, it may be added that from Lake Erie to the rapids above the falls the river is from half a mile to more than a mile wide, and flowing at the surface of the country with banks only a few feet high. The gorge is thirty-six thousand five hundred feet long and varies from nine

PSM V49 D020 Sectional view of the falls.jpg
Fig. 8. — Section at the Site of the Falls, showing the Transverse buried Tonawanda Valley, F, cut out of limestones for breadth of a mile and a half and depth of ninety feet: rectangular shading represents the Niagara limestones; L O, level of Lake Ontario; F, foot of falls.

hundred feet to fourteen hundred feet wide at the top, and it is three hundred and forty feet deep near the outlet. The width of the river itself at the narrows is only three hundred feet and four hundred at outlet of whirlpool, although elsewhere much broader. The rubbish in the chasm forms loose heaps of broken rock, which is constantly falling from the sides, and building up sloping banks along the water's edge, where the rains and river are constantly washing them away, and thus the cañon is slowly being widened into a common form of an old valley. The river, both near the foot of the falls and seven miles below, at the outlet of the gorge, is nearly one hundred feet in depth, descends fifty feet by the rapids above the falls, which leaps one hundred and fifty-eight feet into the abyss, from which it further descends another hundred and ten feet by the rapids below the falls. These features are