140 Mr. Lyell on Fossil and recent Shells 



It is evident from the manner in which large fragments of rock are irregularly 

 interspersed among the shelly strata near Quebec, as described by Capt, Bayfield, 

 that when these deposits were taking place the transportation of blocks by ice was 

 going on continually, as at the present moment, in the St. Lawrence. 



I have mentioned that many of the testacea which now inhabit the Gulf of St. 

 Lawrence, lat. 48° N., and some others which are found fossil in the Beauport beds, 

 are of the same species which now live in the Northern Ocean between the lati- 

 tudes 60° and 75° N. Perhaps the constant melting of ice in the Gulf may have 

 some influence in promoting the range of northern species by cooling the waters 

 to a temperature below that of the air in summer. This effect may be produced 

 not only by the great quantity of ice which is drifted in the spring from Baffin's 

 Bay along the coast of Labrador and then through the Straits of Belle Isle into the 

 Gulf of St. Lawrence, but also by the ice which descends the St. Lawrence itself. 

 This cause may help to assimilate the temperature of the sea in Canada at a certain 

 depth to that which belongs to it nearer the surface much farther north. The 

 wide distribution of species alluded to may be favoured, not only by the direction 

 of the great current which runs from Baffin's Bay southward, and which may drift 

 along the eggs of mollusca, or their young, but also by the ice islands themselves, 

 which are continually stranding on all parts of the coasts and again leaving the 

 same, so that they may carry away with them not only mud, sand and blocks of 

 granite, but also many entire and living shells. 



In a letter, dated Nov. 1837, Capt. Bayfield says, " Last spring I watched the 

 ice of Lake St. Peter, which takes two or three days to pass Quebec every spring, 

 and had the pleasure to observe several boulders of considerable size, and many 

 small stones, sand, earth, reeds, and plants on their way down the river, drifting along 

 at a rate measured by the excess of every ebb tide over the preceding flood. The 

 latter flows 4f hours at the rate of three knots, the former about 7^ hours at four 

 knots. Any boulders and other matters which are thus transported are liable to 

 be dropped, at various points along the bed of the river, as the ice gives way to the 

 increasing temperature of the air and water in the spring of the year. The fresh- 

 water shells, which are often found washed up on the beaches, are doubtless carried 

 low down the estuary in this way, being frozen into the mass of ice which forms 

 on the shoals where they abound." 



I have spoken of the deposit at Beauport and other places as belonging to the 

 most modern tertiary or newer Pliocene period, and the only doubt which can be 

 entertained as to its age is, whether it ought rather to be referred to the post-ter- 

 tiary era, or to that in which all the shells are identical with species now existing. 

 As the number hitherto obtained amounts to no more than sixteen, it would be 

 premature to offer a positive opinion on this subject. Some conchologists would 



