1*78 Canadian Record of Science. 



The present essay is based on' the investigation of both 

 these large areas, and of a dozen of smaller ones, which are 

 found in the neighborhood of the Morin area, as well as on 

 a careful study of the literature on the whole subject. 



n._THE MORIN ANORTIIOSITE AREA. 

 Stratigraphical Relations. 



As will be seen from a study of the accompanying map 1 

 the Morin area consists of a mass of anorthosite nearly 

 circular in form, from the south-east side of which a long 

 arm-like extension projects. This mass is 3*7 miles in 

 diameter and with the arm-like extension just mentioned 

 has an area of 990 square miles. It is bounded on all sides 

 by rocks of the Grenville series with the exception of the 

 extremity of the arm-like extension, which stretching much 

 farther south than the main portion of the mass, is overlaid 

 and concealed by more recent strata of Cambrian age (Pots- 

 dam and Calciferous). 2 



The Grenville series consists, as has already been point- 

 ed out, of orthoclase gneiss, of many different varieties, 

 with interstratified beds of quartzite, amphibolite and crys- 

 talline limestone. The gneiss is generally well foliated and 

 in many places is distinctly banded. Its strata lie almost 

 flat in the eastern part of the area, but to the west they are 

 thrown up into a series of folds, which in the extreme west 

 are very sharp. The rocks have a general northerly strike. 

 The crystalline limestones, with the associated garnetifer- 

 ous and rusty weathering gneiss, occur in many places. 

 They are found in thin bands interstratified with the flat- 

 lying gneisess of the eastern part of the area in the cliffs 

 along the shores of numerous lakes in the district. In the 

 western part of the area they often come to the surface in 

 consequence of the folded attitude of the beds already refer- 

 red to. 



1 Since the appearance of the paper the railroad has been continued past St. 

 Agathe to St. Faustin and thence to Chute aux Iroquois, beyond the limits of the 

 map. Another line also extends from St. Jerome to New Glasgow and thence 

 north-eastward to St. Juilenne. 



2 It is probable that some of the rocks bounding it on the north-western portion 

 of its extension should rather be referred to the Fundamental Gneiss. 



