850 CPR PTT 
Mountain range, and in the anticline east of Memphremagog Lake 
near Fitch Bay. 
The crystalline schists of the Sutton Mountain range may be 
divided into two principal portions, viz., the gneissic, micaceous, 
quartzose, and talcose schists of the central portion or that in which 
the axis of the anticline is situated, and a series of green, chloritic, 
schistose rocks, with the characters of altered dioritic rocks, constitut- 
ing an easily separable portion, flanking the central area of schists to 
the west, and extending from the Vermont boundary to the St. Francis 
in the vicinity of Richmond. This second or chloritic division is 
recognized also at various points on the eastern slope of the range, but 
it does not there present so marked a development. The age of the 
green schistose, dioritic portion is doubtful, but it appears to coincide 
to some extent with the Volcanic Group of Selwyn,’ which he supposed 
to be probably Lower Cambrian or Huronian. 
East of Memphremagog Lake, near Fitch Bay, the pre-Cambrian 
rocks are schistose, altered, dioritic rocks, occasionally with micaceous 
bands, and often containing clear grains of quartz. ‘These rocks are 
apparently allied to the green chloritic schists of the west slope of the 
Sutton Mountain range, and are placed on the map as doubtfully 
Huronian. 
Cutting the pre-Cambrian rocks, and possibly also later sediments, 
are a considerable variety of rocks, such as granites, syenites, diorites, 
diabases, serpentines, traps, etc., evidently of different ages. It is 
probable that the age of the granites is not far from the close of the 
Silurian period. 
Adams?’ describes and maps the Laurentian area north of the St. 
Lawrence River, in the northwest corner of the southwest sheet of the 
“Eastern Township” map (Montreal sheet). This Laurentian area is 
a portion of the southern margin of the great northern Canadian area 
of Laurentian rocks. The area is about equally divided between the 
rocks of the Laurentian system and intrusions of anorthosite which 
break through them. The Laurentian? consists of red and gray ortho- 
Stratigraphy of the Quebec Group and the older crystalline rocks of Canada, by 
A. R. C. SELWYN. Rept. Geol. Surv. of Can., for 1877-8, Part A, p. 3. 
2 Laurentian area inthe northwest corner of the Montreal sheet, by F. D. ADAms. 
Supplementary chapter to Ell’s report on a portion of the Province of Quebec. Ann. 
Rept. Geol. Surv. of Canada for 1894, Vol. VII, Part J, 1896, pp. 93-112. 
3The term Laurentian is thus used as it was by Logan. 
