522 J^fof. Ramsay, on the Geological Causes [April 30, 



WEEKLY EVENING MEETING, 



Friday, April 30. 



The Duke of Northumberland, K.G. F.R.S. President, 

 in the Chair. 



Professor Andrew C. Ramsay, F.R.S. 



On the Geological Causes that have influenced the Scenery of 

 Canada and the North-Eastern Provinces of the United States, 



It is impossible thoroughly to explain all the points of this dis- 

 course without the aid of the pictorial illustrations and sections 

 employed on the occasion, and therefore in this abstract only 

 some of the leading geological features are noticed. 



The island of Belleisle and the Laurentine chain of mountains 

 between the shores of Labrador and Lake Superior consist of 

 gneissic rocks older than the Huronian formation of Sir Wm. Logan. 

 This gneiss is probably the equivalent of the oldest gneiss of the 

 Scandinavian chain, and of the north-west of Scotland, underlying 

 that conglomerate, which, according to Sir Roderick Murchison, in 

 Scotland represents the Cambrian strata of the Longmynd and of 

 Wales. The mountains of the Laurentine chain present those 

 rounded contours that evince great glacial abrasion ; and among 

 the forests north of the Ottawa the mammillated surfaces were 

 observed by the speaker to be often grooved and striated, the 

 striations running from north to south. The whole country has 

 been moulded by ice. Above the metamorphic rocks, in the 

 plains of Canada and the United States south of the St. 

 Lawrence, and around Lake Ontario and Lake Erie, the Silurian 

 and Devonian strata lie nearly horizontally, but slightly inclined 

 to the south. Consisting of alternations of limestone and softer 

 strata, the rocks have been worn by denudation into a succession 

 of terraces, the chief of these forming a great escarpment, part of 

 which, by the river Niagara, overlooks Queenston and Lewis- 

 ton, and capped by the Niagara limestone, extends from the 

 neighbourhood of the Hudson to Lake Huron. Divided by this 

 escarpment the plains of Canada bordering the lakes, and part of 

 the United States, thus consist of two great plateaux, in the 

 lower of which lies Lake Ontario, Lake Erie lying in a slight 

 depression in the upper plain or table land, 329 feet above Lake 

 Ontario. The lower plain consists mostly of Lower Silurian rocks, 

 bounded on the north by the metamorphic hills of the Laurentine 



