18G7.] CROSSKEY— ON GLACIAL DEPOSITS. 207 



ON THE RELATION 



BETWEEN THE 



GLACIAL DEPOSITS OF SCOTLAND AND t TIIOSE OF CANADA. 

 By the Eev. Henry "W". CROSSKEY. 



Principal Dawson, of Montreal, among his other great services 

 to Geology, has very carefully investigated the Canadian glacial 

 beds, and the following notes are suggested by a study of his 

 writings : — 



I. The difference between the glacial fossil fauna of Canada and 

 that now existing in the Gulf of St. Lawrence is far less marked 

 than the difference between the glacial fauna of the Clyde beds 

 and that now existing in the Firth. The fossil fauna of Canada, 

 in its general aspect, and in the proportions and characteristic 

 varieties of its species, is slightly more arctic than that of the 

 Gulf, but does not present that broad contrast with which we are 

 familiar between the fossil contents of our local clays and - the 

 living inhabitants of our waters. There are only two species in 

 Canada which can be regarded as locally extinct, viz., Leda 

 Porilandica (Gould), and Astarte Laurentiana (Lyell) ; while in 

 Scotland there is a very remarkable list of species fossil in the 

 clay, but extinct through the whole range of the neighbouring 

 seas. Upon the west, we find : 



Tellina calcarca (proximo,.) Mangelia pyramidalis. 

 Saxicava (Panopcea) Nbrvegica. Natica affinis (clausa). 



Astarte borealis. Trophon clathratus (scalar if ormis). 



Leda permila, Yehrtina unclata. 



Pecten Islandicus. Cyclostrema costulatum. 



Modiolaria discors. Balanus cariosus {Darwin). 

 Littorina limata (Loven). 



The eastern clays comprise extinct species even more artic in 

 character, viz. : — 



Leda arctica (Porilandica, Gould). Thracia myopsis. 



„ lncida. Cardium Grocnlandicum. 



„ thraciseformis. Scalaria Groenlandica. 

 Pecten Grcenlandieus. 



It is evident, therefore, from this very marked contrast, that the 

 change of climate in Scotland has been more complete than in 

 Canada. From this fact important physical consequences ensue : 

 the glacial epoch cannot have been caused by any of those 

 cataclysmal agencies to which it has been attributed. Any 

 heaping up of the land at the North Pole; or passage of the earth 



