10 
Precambrian 
The rocks of greatest interest for this purpose are the schists mapped 
as Precambrian, and the eruptives, both making important parts of the 
higher mountains and both including resistant types of rock. They 
should, therefore, be described more fully. 
The Precambrian, as mapped near the headwaters of Ste. Anne and 
Cap-Chat rivers, includes hornblende and chlorite schists, frequently 
found as boulders or pebbles in glacial deposits, mica schist, not found 
far away from its source, and slate, hardly distinguishable from the 
Cambrian slates to the north. No gneiss or granite is known to occur 
in this belt of Precambrian. 
The best Precambrian section, so far as the writer is aware, is on 
the east side of lake Matapedia, forming the southern half of its shore and 
occurring also on four islands. 
A hill near the southeast corner of the lake consists of pale grey, 
rather glassy quartzite, showing no stratification, and, probably, forms 
the southern side of the band of Precambrian. This quartzite is more 
ancient looking than any of the quartzitic sandstones observed among 
the later rocks. 
The islands at the south end of the lake consist of fine-grained, massive- 
looking greenstone and grey-green schist, but on the mainland to the east 
epidotic amygdaloids with pillow structure occur, and seem to penetrate 
pale grey arkose which encloses a few pebbles. These met amorphic 
rocks resist well and provide important data as to the ice motions, since 
they are > on the whole easily distinguished from the later sedimentary 
materials. 
Paleozoic Eruptives 
Most valuable of all are the eruptives, especially those occurring 
in the higher parts of the Shickshocks, since they not only resist well, but 
are readily recognized in drift deposits. They include granites and 
rhyolites and also very basic rocks such as porphyrites and peridotites. 
The granites will be referred to first. 
The highest part of the mountains, called Tabletop, is formed mainly 
of granite supposed to be of Post-Devonian age, since it disturbed Devonian 
rocks in its eruption. It is found in contact with rocks of all ages from 
Precambrian to Devonian and has somewhat modified them by contact 
metamorphism. 
The main area of granite lies crosswise of the trend of the Shickshock 
structures, with a length from north to south, as shown on the geological 
map, of about 12 miles, and a width of about 4 miles.. There are also 
isolated peaks of porphyry rising through the Devonian just to the south 
and west of the main area. 
The granite, so far as observed, is fine to medium-grained and pale 
pink or reddish in colour. Gneissoid or pegmatitic varieties have not 
been found. It is a very distinctive rock quite unlike the coarse-textured 
granites, gneisses, and pegmatites common in the Laurentian north of the 
St. Lawrence. 
