Page:Popular Science Monthly Volume 38.djvu/766

746 period of conflict between the ice and the river must have "been a terrible time for the lower Ohio Valley and its inhabitants. At times the river was dry, and at others bank-full and overflowing. The frost of winter by lessening the supply, and the ice-tongue by forming a dam, combined to hold back the water. The sun of summer, by melting the dam, and the pressure of the accumulated water, by bursting it, combined to let off at once the whole of the retained store. Terrible floods of water and ice, laden with stones, gravel, and sand, must have poured down the river, and have swept everything away in their path—trees, animals, and man, if present. . . . To the human dwellers in the Ohio Valley—for we have reason to believe that the valley was in that day tenanted by man—these floods must have proved disastrous in the extreme. It is scarcely likely that they were often forecast. The whole population of the bottom lands must have been repeatedly swept away; and it is far from being unlikely that in these and other similar catastrophes in different parts of the world, which characterized certain stages in the Glacial era, will be found the far-off basis on which rest those traditions of a flood that are found among almost all savage nations, especially in the north temperate zone."

So there finally came a time when the Ohio Valley was no longer blocked by ice. But, when this time came, the débris from the melting glaciers had filled up the previously northward trending channel, while the long-continued floods had cut a new channel along the southern border of the ice as far as the mouth of the Big Miami. Thus was its ancient bed deserted forever, and was left to be occupied by insignificant streams, or else remained high and dry above the reach of any flood of future years.

The city of Louisville stands upon a deserted portion of the Ohio River channel also. It is in front of this city that the celebrated Falls of the Ohio are found. Here the river rushes over a rocky bottom, of itself indicative of a new channel, while on either side are wide stretches of sand or gravel, or low-lying plains through which the river formerly flowed. A late writer in one of the scientific magazines states that evidence points to the fact that in pre-glacial times the Ohio River divided above the city, one branch flowing on the north and another on the south of an island, the two uniting again below the city. Well-borings show the rock in some places to be one hundred and fifty feet or more below the present surface, and what are now insignificant streams were once large enough to carve valleys half a mile wide and many feet in depth. Where was once the island, are now the falls. The ancient channels are filled with débris, and the new channel is a shallow rock cut, excavated since the close of the great Ice age.