212 REPORT ON CORRELATION 
conforms to those which have already been described from the areas 
visited by the committee. 
In the eastern part of the original Laurentian area Logan found 
a large mass of anorthosite, which may be termed the “ Morin anortho- 
site.” This formed the eastern limit of the area which he mapped. 
This anorthosite he found to be in some places more or less distinctly 
foliated, which foliation he regarded as a survival of an almost obliter- 
ated bedding. He furthermore found that the limestone bands in 
the sedimentary series disappeared on coming against this mass of 
anorthosite. From these two facts he concluded that the anorthosite 
belonged to an unconformable, although highly metamorphosed, 
sedimentary series, which unconformably overlay the Grenville 
series, whose limestones he considered to pass beneath the anorthosite 
mass. 
Adams, in continuing Logan’s work to the east, had occasion to 
map and thoroughly study this anorthosite body. He found it to 
have the shape of a clover leaf and to have an area of g90 square 
miles. The anorthosite in the central portion, and over the greater 
part of the western half of the mass, is nearly massive, although often 
showing an indistinct brecciated structure. On going from the 
center of the mass toward its eastern boundary, however, this brec- 
ciated structure becomes more and more pronounced, the angular 
fragments being imbedded in a progressively larger amount of granu- 
lated ground-mass, while along the eastern border the mass becomes 
perfectly foliated, the angular fragments disappearing almost entirely. 
These angular fragments and the ground-mass are identical in compo- 
sition, both being composed essentially of plagioclase. The frag- 
ments represent portions of the original coarsely crystalline rock in 
an uncrushed condition, the ground-mass being produced by the 
granulation and breaking-down of the original rock, of which the 
brecciated fragments are the surviving remnants. The fragments 
in the breccia, like the rock when in a massive form, are deep-blue 
in color, while the granulated rock has lost this blue color and is 
gray, sometimes nearly white. This is due to the disappearance of 
the minute inclusions so abundant in the plagioclase feldspar of all 
these anorthosites which have not been crushed. Where the rock 
becomes perfectly foliated, as along the eastern border of the anortho- 
