98 Geology and Topography of Western New York. 



to four or six feet, it is underlaid by a very fine deposit of clay, 

 horizontally stratified, containing fragments of limestone similar 

 to the rock beneath. It appears to belong to the extensive clayey 

 deposit, which covers large tracts on the limestone range, and in 

 which I have never met with any fossil remains ; although they 

 may, and probably will hereafter, be detected. 



The extent and power of these counter currents, which exca- 

 vated the valley of the Niagara, and assisted in cutting down the 

 ravine below the falls, remain to be determined, when the laws 

 which govern the ebb and flow of tides shall be fully developed, 

 and when the shape of this ancient gulf, at this stage of eleva- 

 tion, shall be approximately ascertained. It is well known, that 

 the height and violence of tides are materially modified by the 

 direction of prevailing winds, by oceanic currents, and by the 

 shape of coasts and estuaries. At some places on the coast of 

 England, as in the Bristol channel, the tide rises forty-two feet,* 

 and in the Bay of Fundy, to the enormous height of from sixty 

 to one hundred feet.f As no land which is now less than 575 

 feet above tide water, had then emerged from the ocean — unless 

 its rise was less rapid than this region, and the reverse is probably 

 true of the primitive districts — this arm of the sea had ample 

 communication with the Atlantic, through the Gulf of St. Law- 

 rence, and the valley of the Hudson. At this stage^ the primitive 

 range in the north of this State, and those in the New England 

 States, were but islands ; and it is not improbable, when the rel- 

 ative levels shall be ascertained, that other passes will be found, 

 at a less elevation above tide water than Lake Erie. Receiving 

 the tidal wave, therefore, through these difi'erent channels, which 

 would meet in the vicinity of Lake Ontario, an additional im- 

 pulse would be communicated to it, and a tide would probably 

 result, little. inferior to that at either of the places above cited. 



There is another phenomenon connected with tides, which 

 ought not to be forgotten. If, as suggested, this strait received a 

 powerful tide, it might, when rushing up the narrow gorge above 

 Lewiston, have produced that kind of tidal wave, called the 

 " Bore," which, says Lyell,J " is sometimes produced in a river, 

 where a large body of water is made to rise suddenly, in conse- 



* Lyell's Geology, Vol. i, p. 238. 



t See Audubon's Birds of America, Vol. ii, p. 448. Also, American Journal, Vol. 

 XV, p. 132. Also, Rees's and the American Encyclopedias. 

 t Lyell's Geology, Vol. i, p. 274. 



