Changes in the Belative Level of Sea and Land. 311 



many hundred feet, since the deposition of these shells. At 

 the village of Beauport, three miles below Quebec, he made 

 a collection of shells from a cliff consisting of a series of beds 

 of clay, sand, gravel and boulders ; and he states that when 

 they arrived in London, Dr Beck of Copenhagen happened to 

 be with him ; and " great was our surprise," he adds, " on 

 opening the box, to find that nearly all the shells agreed spe- 

 cifically with fossils which, in the summer of the preceding 

 year, 1 had obtained at Udde valla in Sweden, and figured in 

 my paper * On the Rise of Land,' &c. in the ' Philosophical 

 Transactions' for 1835. Among the species most abundant 

 in these remote regions (Scandinavia and Canada) were Saxi- 

 cava rugosa^ Mya truncatay M. arenaria, Tellina calcarea, T. 

 Grcenlandica, Natica clausa, and Balanus Uddevallensis. All 

 of them are species now living in the northern seas ; and 

 whereas I had found them fossil in latitudes 58° and 60° N., 

 in Sweden, Captain Bayfield sent them to me from a part of 

 Canada, situated in latitude 47° N." 



Ascending the St Lawrence, he found near Montreal, at a 

 height of about sixty feet above the river, great numbers of 

 the Mytilus edulis, retaining both valves and their purple 

 colour, associated with Tellina Grcenlandica and Saxicava ru- 

 gosa, in horizontal beds of loam and marly clay. He found 

 the same shells at ninety feet associated with boulders of 

 gneiss and syenite three feet in diameter, characteristic of the 

 Canadian drift ; and he was afterwards conducted to a hollow 

 between the two eminences which form the Montreal moun- 

 tain, where he found a bed of gravel six feet thick, containing 

 numerous valves of Saxlcava rugosa and Tellina Grcenlandica. 

 This bed he estimates at 540 feet above the sea, 306 feet 

 above Lake Ontario, and only 25 feet below the level of Lake 

 Erie. 



Such comparatively modern changes in the relative level 

 of the land and sea, were ascribed by the earlier geologists, 

 and are by some still ascribed, to a rising or sinking of l/ie 

 sea. Playfair, nearly half a century ago, combating this 

 opinion maintained by the Swedish naturalist Celsius, de- 

 monstrated the untenable nature of such an hypothesis; it was 

 he who first shewed that these changes of relative level are 



