Mr. Lyell on the Ridges, fyc. of the Canadian Lakes. 183 



scribed, with beautiful diagrams in illustration of the memoir, were 

 presented to the Society by Dr. Dale Owen at this meeting. 



2. On the Ridges, Elevated Beaches, Inland Cliffs and Boulder For- 

 mations of the Canadian Lakes and Valley of the St. Lawrence. By 

 Charles Lyell, Esq., V.P.G.S., F.R.S.* 



After adverting to his former paper on the Recession of the Falls 

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

 Hall in the autumn of 184 If, Mr. Lyell gives an account of addi- 

 tional 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 freshwater strata of sand and gravel here 

 alluded to occur at the Whirlpool. They are horizontal, 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 boulder 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 freshwater shells, was detected 

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

 flows in, about l£ mile above the Whirlpool. From the position of 

 these strata it is inferred that the ancient bed of the river, somewhere 

 below the Whirlpool, must have been 300 feet higher than the pre- 

 sent 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 freshwater beds of the Whirlpool and Goat Island 

 come into immediate contact with the subjacent Silurian limestone, 

 no drift intervening, shows that the original valley of the Niagara 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 rock 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 

 examined in detail by the author, and found to be connected with 

 the valley of St. Davids, about three miles to the north-west. This 

 ancient valley appears to have been about two miles broad at one 

 extremity, where it reaches the great escarpment at St. Davids, and 

 between 200 and 300 yards wide at the other end, or at the whirl- 

 pool. Its steep sides did not consist of single precipices, as in the 

 ravine of Niagara, but of successive cliffs and ledges. After its de- 



* Read Dec. 14, 1842, and January 4, 1843. 



t See Proceedings, vol. iii. p. 595 [or Phil. Mag. S. 3. vol. xxi. p. 



548]. 



