﻿Book Notices. 453 



western terminus is beyond the limits of the map. The altitude of 

 each station is printed underneath the name, and may be taken as 

 approximate for the immediate surrounding country. 



The Montfort Colonization Railway connects with the Canadian 

 Pacific at Montfort Junction, and runs in a westerly direction, crossing 

 the Lauientian, the southern edge of the Morin anortliosite, and at 

 present terminates on the former, at Lac de Seize Isles. 



The Northern Railway runs north-east from St. Jerome, but only for 

 a short distance on the Lauren tian. 



This area of the Archaean, however represented on the map, is only 

 a small part of the vast northern Protaxis, which extends from 

 Labrador south-west to Lake Superior, and thence north-west to the 

 Arctic Ocean, and from which the Continent of North America was in 

 great part built up. 



The Archaean in this particular district comprises the Laurentian 

 proper and the anorthosites. 



It forms a plateau, which rises abruptly from the Palseozoic plain in 

 the south-east, its southern portion averaging about 1,000 feet above 

 the level of the sea, but gradually rising towards the north, it attains 

 at that limit a height of 1,900 feet. A few hills are higher, such as 

 Trembling Mountain and those of Ste. Agricole. The surface of the 

 plateau is very uneven, the hills being rounded and very often bare, 

 while the valleys between them are filled with drift, and constitute 

 good farming land. Lakes of all sizes abound, and are drained by 

 several rivers, tributary to the Ottawa and St. Lawrence. 



The Morin anorthosite, though somewhat higher than the surround- 

 ing Laurentian, in some places rising from it very abruptly, still has 

 the same general characteristics. 



The Laurentian proper is divided into the Fundamental Gneiss and 

 the Grenville Series. The former, as far as our present knowledge 

 concerning it goes, is of igneous origin. The latter is of partly sedi- 

 mentary origin, but associated with much igneous material. It is 

 composed of gneisses, limestones and quartzites, which are interbanded 

 with one another, and are highly metamorphosed. 



These bands, or strata, in the extreme east lie in a horizontal position, 

 further west they undulate, increasing in intensity, until after Rad- 

 stock and Ste. Emelie have been passed, they become highly contorted, 

 continuing so to the contact of the Morin ma^s. This is excellently 

 shown in three cross sections, which appear on the same sheet as the 

 map. The gneiss at this contact shows evidence of being stretched, 

 the least plastic rock or mineral in it having a tendency to pull apart. 



The rocks of the Laurentian are divided into the following five 

 classes : gneisses, quartzites, garnet rock, pyroxene rock, and crystal- 

 line limestones. The gneisses are characterized by their foliated 

 structure, which may vary from very distinct to almost indistinct. 



