CENTRAL CANADA PART V. 



345 



mountainous Laurentian region of the northern portion of the Pro- 

 vince. The average elevation of the. Gaspe peninsula is about 1500 

 feet, and that of the other parts of the district about 800 to 1000 

 feet above the sea ; but several peaks in the Shickshock ranges of 

 Gaspe approach 4000 feet in height, ;md the summits of some of the 

 mountains in the Eastern Townships are apparantly over 3000 feet. 

 Many lakes, but none of large size, occur within the district. Among 

 these, Lake St. Francis lies at an elevation of 890 feet, and Lake 

 Memphramagog at an elevation of 760 feet above the sea. In Gaspe" 

 Lake Temiscouta and Lake Matapedia lie respectively at altitudes of 

 470 and 480 feet. The district is greatly intersected by streams and 

 rivers. Some of the principal comprise : the Yamaska and the St. 

 Francis, the Chaudiere (with its tributaries, the Famine, Des Plantes, 

 etc.,) and the Etchemin, in the more western portion of the district ; 

 and the Riviere du Loup, Trois Pistoles, Rimouski, Metis, Matanne, 

 Chatte, St. Anne, Magdalen, Cascapediac, Matapediac, and other 

 rivers of the Gaspe peninsula, most of which flow in deeply excava- 

 ted channels. 



The geology of this district, so far as regards the actual sequence 

 and relations of the rock groups within its area, is still very imper- 

 fectly known, and much diversity of opinion prevails respecting the 

 true age and position of some of these formations. 



Viewed broadly, the district may be regarded as divisible into three 

 sub-areas : (1) a comparatively narrow central zone of mountainous 

 country composed of crystalline and essentially metalliferous rocks, 

 ranging from the Dominion boundary near Lake Champlain, through 

 Sutton, Brome, Stukely, and other " Eastern Townships," in a north- 

 easterly direction across the Chaudiere River as far as the County 

 of Kamouraska, and re-appearing farther east in the Shickshock 

 Mountains of Gaspe ; with (2), a somewhat broader band between it 

 and the St. Lawrence, composed of Cambrian and Lower Silurian 

 strata ; and (3), a still broader area, underlaid essentially by Upper 

 Silurian and Devonian beds, along its southern border. These areas 

 are broken through in places by eruptive dykes and mountain- 

 masses ; and are overlaid very generally by Drift and other sur- 

 face-deposits. 



Four series of rock-formations are thus recognizable within the 

 district. These comprise : (1), Crystalline and sub-crystalline forma- 



