Glacial Phenomena of Canuda. 339 



stratified clay and sand, overlying an older blue clay (the older 

 drift), in which were found, by Prof. Zadoc Thompson, Sanguino- 

 lariafusca, Mya arenaria, Saxicava rugosa, Mytilus edulis. and 

 the bottom the bones of a Cetacean associated with S. Rugosa 

 and a Niicula or, more probably, Leda. The Leda clay of Dr. 

 Dawson, at Montreal, is also about 120 feet above the river, or 

 140 feet above the level of the sea. If the so-called u Niicula" 

 of Lake Champlain be Leda Portlandica, the Montreal beds con- 

 tain the same assemblage of fossils (except Sang id nolaria fusca)* 

 In the Montreal beds Sir Wm. Logan also found a number of the 

 caudal vertebrse of a Cetacean. The beds at Green's Creek, Ot- 

 tawa, containing the same assemblage of shells, Mallotus villosus 

 and remains of Seals, are 118 feet above Lake St. Peter, and 140 

 to 150 feet above the sea. Marine shells [Saxicava rugosa, Mya 

 Mytilus edulis and Tellina Groenlandicd) occur at Kingston, at 

 the entrance to Lake Ontario. Dr. Dawson shows good reason 

 why the above-named fossiliferous deposits on the St. Lawrence 

 and Ottawa should be considered equivalents. In addition, I am 

 of opinion that this conclusion may be extended to the Kingston 

 beds, and that the beds of Lake Champlain leading down to those 

 of the Hudson are of the same date; and if so, then I cannot 

 doubt that the laminated clay that overlies the older boulder-drift 

 of the Hudson Valley is a large development of the same forma- 

 tion, the whole having been deposited at the close of the drift- 

 period. In that case, a long marine strait filled the valley of the 

 Hudson, and communicated with the sea that, according to Dr. 

 Dawson, then occupied the whole of Lower Canada south of the 

 Laurentine Chain, and, stretching westward, covered the area of 

 Lake Ontario, and washed the great Niagara escarpment which 

 formed its southern coast. 



Probable date of the origin of NiagaraFalls. — It has been shown 

 by Mr. Hall and Sir Charles Lyell, that when the Niagara escarp- 

 ment rose above the water, the Falls of Niagara began by the 

 drainage of the upper lake-area falling into the sea over the edge 

 of the escarpment above Queenstown and Lewistown. It is not 

 improbable that Lake Erie extended at that period much further 

 towards the present foils; and, agreeing in the general conclusions 

 of these observers and of Dawson, it follows that if the sea of the 

 Leda-clay washed the base of the escarpment, the Falls of Ni- 



* This is without doubt a Synonym for Tellina Grcenlandica, a com- 

 mon shell at Montreal. Ed. 



