SOME LOCAL DETAILS. 193 



is further shown by its shells, which are, on the whole, a 

 more modern assemblage than those of the Leda clay of 

 Montreal. In fossils, as well as in elevation, these beds 

 more nearly resemble those on the coast of Maine. It 

 would thus appear that the boulder-clay is not a continuous 

 sheet or stratum, but that its different portions were 

 formed at different times, during the submergence and 

 elevation of the country ; and it must have been during 

 the latter process that the greater part of the deposits 

 now under consideration were formed. 



The assemblage of shells at Riviere-du-Loup is, in 

 almost every particular, that of the modern gulf of St. 

 Lawrence, more especially on its northern coast. The 

 principal difference is the prevalence of Leda arctica in 

 the lower part of the deposit. This shell, still living in 

 Arctic America, has not yet occurred in the gulf of St. 

 Lawrence, but is distributed throughout the lower part of 

 the Pleistocene deposits in the whole of Lower Canada 

 and New England, and appears in great numbers at 

 Riviere-du-Loup, not only in the ordinary form, but in the 

 shortened and depauperated varieties which have been 

 named by Reeve L. siliqua and L. sulcifera. 



Of Astarte Laurentiana, supposed to be extinct, and 

 which occurs so abundantly in the Pleistocene at Montreal, 

 few specimens were found, and its place is supplied by 

 an allied but apparently distinct species, to be noticed in 

 the sequel, which is still abundant at Gaspe and Labrador, 

 and on the coast of Nova Scotia. 



It must be observed that though the clays at Riviere- 

 du-Loup are more recent than those of Montreal, they are 

 still of considerable antiquity. They must have been 

 deposited in water perhaps fifty fathoms deep, and the 

 bottom must have been raised from that depth to its 



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