746 THE POPULAR SCIENCE MONTHLY. 



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 accumu- 

 lated 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 charac- 

 terized 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 debris from 

 the melting glaciers had filled up the previously northward trend- 

 ing channel, while the long-continued floods had cut a new chan- 

 nel 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 

 debris, and the new channel is a shallow rock cut, excavated since 

 the close of the great Ice age. 



* John Bryson, in American Geologist, March, 1890. 



