1/6 The Ottawa Naturalist. [December 



aspectof Pre-Cambrian schistsand for a time these mountains were 

 supposed to be as old as the lowest Cambrian. Their intimate as- 

 sociation with Silurian and Devonian sediments at a number of 

 points, together with the fact that numerous spurs were given 

 off from the main masses of igneous rocks which penetrated these 

 newer sediments in the form of d /kes, the fossiliferous Silurian 

 and Devonian in contact being frequently converted into schists 

 and otherwise altered, shews conclusively that the age of most 

 of these mountain masses must be more recent than the sediments 

 which they penetrate so that they are at least post-Silurian. 



There are however large areas of igneous rocks in as- 

 sociation with the pre-Cambrian strata of the Sutton Mountain 

 axis which are of Pre-Cambrian age, since they are overlaid by the 

 slates of the lowest Cambrian. These have also been altered 

 and are now often seen in the form of chloritic and other schists. 



The age of the Granite masses which are conspicuous features 

 in the eastern portionof Quebec,is probably notvery different from 

 that of the diabase hills just referred to. These cut rocks of all ages 

 from the pre-Cambrian to the Silurian. The strata in their 

 vicinity are all greatly altered, the slates being changed into 

 chiastolite and staurolite schists, w^hile the Cambro-Silurian 

 limestones have been rendered schistose and are filled with small 

 scales of mica, often with a large development of quartz veins. 



The serpentine areas in which the asbestus of the Eastern 

 Townships is frequently found apparently belong to the dia- 

 base and olivine group. They are often found in association 

 with the Cambrian slates but they also occur in connection with 

 the Cambro-Silurian and Silurian strata. They are apparently 

 altered portions of the diabase and olivine masses. 



The same remarks apply to most of the igneous rocks of the 

 Gaspe peninsula. These is here a central zone of pre-Cambrian 

 rocks, overlaid on the north by Cambrian slates and limestones, 

 and on the south by Silurian and Devonian strata of the great 

 Siluro-Devonian basin. Through these newer rocks great 

 mountain masses of diabase and kindred rocks protrude ; similar 

 to those found in the areas east of the St. Lawrence, and these 

 are evidently newer than the fossiliferous sediments which they 

 penetrate, since, at several points, pieces of the fossiliferous lime- 

 stones are caught and held in the igneous mass. 



