294 On the Boulders of Primitive Rocks found in Ohio, fyc. 



such a theory, to demonstrate, at least the possibility of such 

 a great mass of water being collected at the north, to sweep 

 over this continent, or the conjecture that such was the fact 

 must remain one of very doubtful authority. 



The surface of Lake Erie is five hundred and sixty-five 

 feet above the Atlantic ocean, and three hundred feet above 

 Lake Ontario. If the water flowing into Lake Erie, were 

 to raise it fifty feet, it would find its way into Lake Ontario 

 by a channel probably eighty or ninety miles wide.* Lake 

 Erie must be raised upwards of three hundred and thirty-four 

 feet to pour any of its waters into the Sciota country or 

 Miami valley, and upwards of six hundred feet to reach the 

 highest grounds on which the boulders are deposited. The 

 dividing ridge, (as it is sometimes called,) between the waters, 

 flowing northward into the lakes, and southward into the 

 Ohio and Mississippi, is about one thousand two hundred 

 feett above Lake Erie ; where the head waters of the Alle- 

 gany river run out of it, it continues to keep up the appear- 

 ance of a ridge of land to the westward, until it reaches 

 near to the west line of Pennsylvania, and is, on the turnpike 

 road from Erie to Waterford about seven hundred feet 

 above the lake ; west of that line the ridge entirely disap- 

 pears, and the waters flow north and south from a level and 

 swampy country ; not unfrequently, the same swamp is 

 drained, upon one side, into the St. Lawrence and upon the 

 other, into the Gulf of Mexico. This dividing ground in the 

 state of Ohio, has been ascertained, by actual measurement, 

 in the lowest place, to be three hundred and thirty-four feet 

 above Lake Erie. It is, however, of unequal elevation ; in 

 some places certainly five hundred and fifty, and probably in 

 others, six hundred feet above the lake, and if we take Lake 

 Michigan to be, as represented, not more than twenty-five 

 feet higher than Lake Erie, the lowest ground dividing the 



* I infer this from a view of the country on each side of Niagara river, and 

 from the fact mentioned by Doct. Bigsby, (Journal of Science, vol. 8, p. 69,) 

 that the "York Highlands" and "Burlington heights," some of the highest 

 grounds in that region, are hut three hundred feet above Lake Ontario, that is, 

 they rise to the level of Lake Erie. 



t Darby's Tour, p. 175. The opinion, here given by Mr. Darby, is probably 

 correct, for the Allegany river, after its long and rapid course from the state of 

 New York to its junction with the Monongahela, is still considerably higher 

 than Lake Erie. Thirty miles below the junction, at the mouth of the Big 

 Beaver, the Ohio river is one hundred and twenty -seven feet above the level of 

 Lake Erie. 



