314 Geology of the Valley of the St. Laiorence, Sfc. 



Art. XI. — On the Ridges, Elevated Beaches, Inland Cliff's and Boul- 

 der Formations of the Canadian Lakes and Valley of St. Lawrence ; 

 by Charles Lyell, Esq., F. G. S., F. R. S., &c* 



After adverting to a former paper on the recession of the Falls of 

 Niagara, and the observations which he made jointly with Mr. Hall in 

 the autumn of 1841, (see Proceed. Geol. Soc. Vol. Ill, p. 595,) Mr. 

 Lyell gives an account of additional investigations made by him in 

 June, 1842 ; in the course of which he found a fluviatile deposit similar 

 to that of Goat Island, on the right bank of the Niagara, nearly four 

 miles lower down than the great Falls. The fresh-water strata of sand 

 and gravel here alluded to occur at the Whirlpool. They are horizon- 

 tal, about forty feet thick, plentifully charged with shells of recent 

 species, and are placed on the verge of the precipice overhanging the 

 river. They are bounded on their inland side by a steep bank of boul- 

 der clay, which runs parallel to the course of the Niagara, marking the 

 limit of the original channel of the river before the excavation of the 

 great ravine. Another patch of sand, with fresh-water shells, was de- 

 tected on the opposite or western side of the river, where the Muddy Run 

 flows in, about one mile and a half above the Whirlpool. From the po- 

 sition of these strata it is inferred that the ancient bed of the river, some- 

 where below the Whirlpool, must have been three hundred feet higher 

 than the present bed, so as to form a barrier to that body of fresh water, 

 in which the various beds of fluviatile sand and gravel above-mentioned 

 were accumulated. This barrier was removed when the cataract cut 

 its way back to a point further south. The author also remarks, that 

 the manner in which the fresh-water beds of the Whirlpool and Goat 

 Island come into immediate contact with the subjacent Silurian lime- 

 stone, no drift intervening, shows that the original valley of the Niag- 

 ara was shaped out of limestone as well as drift. Hence he concludes 

 that the rocks in the rapids above the present Falls had suffered great 

 denudation while yet the Falls were at or below the Whirlpool. 



Mr. Lyell thinks that the form of the ledge of rocks at the Devil's 

 Hole, and of the precipice which there projects and faces down the 

 river, proves the Falls to have been once at that point. An ancient 

 gorge, filled with stratified drift, which breaks the continuity of the 

 limestone on the left bank of the Niagara at the Whirlpool, was ex- 

 amined in detail by the author, and found to be connected with the val- 



* Communicated to this Journal by the author, having been previously read be- 

 fore the Geological Society of London, and published in Vol. IV, No. 92, of their 

 Proceedings. 



