1 84 Mr. Lyell on the Ridges, Elevated Beaches, fyc. 



nudation the valley appears to have been submerged and filled up 

 with sand, gravel, and boulder clay, 300 feet thick. 



A description is next given of certain modern deposits, containing 

 freshwater shells, on the western borders of the Niagara, above the 

 Falls, and in Grand Island, in order to show that the future reces- 

 sion of the Falls may expose patches of fluviatile sediment similar to 

 those in and below Goat Island. 



The author then passes to the general consideration of the boulder 

 formation on the borders of Lakes Erie and Ontario, and in the 

 valley of the St. Lawrence, as far down as Quebec. Marine shells 

 were observed in this drift at Beauport, below Quebec, as first pointed 

 out by Captain Bayfield, and also near the mouth of the Jacques 

 Cartier river, and at Port Neuf and other places ; also at Montreal, 

 where they reach a height probably exceeding 500 feet above the sea, 

 the summit of Montreal mountain being 760 feet high, according to 

 Bayfield's trigonometrical measurement, and the shells being sup- 

 posed to be 240 feet below the summit. These shells, therefore, 

 being more than 300 feet above Lake Ontario, we may presume that 

 the sea in which the drift was formed extended far over the territory 

 bordering that lake. The most southern point at which the author 

 saw fossil shells belonging to the same group as those of Quebec was 

 on the western and eastern shores of Lake Champlain, viz. at Port 

 Kent and Burlington, in about lat. 44° 30'. Here, and wherever 

 elsewhere the contact of the drift is seen with hard subjacent rocks, 

 these rocks are smoothed, and furrowed on the surface, in the same 

 manner as beneath the drift in northern Europe. The species of 

 shells occurring in the drift, to which Mr. Lyell has made some ad- 

 ditions, are not numerous, and are all, save one, known to exist, but 

 are inhabitants, for the most part, of seas in higher latitudes. Many 

 of them are the same as those occurring fossil at Uddevalla and other 

 places in Scandinavia, and they imply the former prevalence of a 

 colder climate when the drift originated. At Beauport there are large 

 and far-transported boulders, both in beds which overlie and under- 

 lie these marine shells. 



The author next describes the ridges of sand and gravel surround- 

 ing the great lakes, which are regarded by many as upraised beaches. 

 He examined, in company with Mr. Hall, the " Lake ridge," as it is 

 called, on the southern shore of Lake Ontario, and other similar 

 ridges north of Toronto, which were formerly explored by Mr. Roy*, 

 and which preserve a general parallelism to each other and to the 

 neighbouring coast. Some of these have been traced for more than 

 100 miles continuously. They vary in height from ten to seventy 

 feet, are often very narrow at their summit, and from fifty to 200 

 yards broad at their base. Cross stratification is very commonly 

 visible in the sand ; they usually rest on clay of the boulder forma- 

 tion, and blocks of granite and other rocks from the north are occa- 

 sionally lodged upon them. They are steeper on the side towards 

 the lakes, and they usually have swamps and ponds on their inland 

 side ; they are higher for the most part and of larger dimensions 



* See Proceedings, vol. ii. p. 537 [or Phil. Mag. S. 3. vol. xi. p. 201]. 



