320 Canadian Record of Science. 



local glaciation has here been such as to convey a large 

 number of serpentine boulders, whose character is unmis- 

 takable, for a distance of three or four miles north of the 

 occurrence of that rock.^ Accordingly the porphyrite 

 may be regarded as the latest intrusion along the serpen- 

 tine belt. 



At a distance of a mile and a lialf north of the locality 

 of the lampropliyre dyke described above, there is an 

 interbedded sheet of amygdaloidal trap rock,^ probably 

 diabase. This is also highly altered in character, and, like 

 the other rocks that have been mentioned, is apparently 

 much older than the dyke. Whether it has any genetic 

 connection either with the dyke or the igneous rocks to 

 the south of it, it is impossible at present to say. The 

 following order of age can, however, be ascertained for the 

 other rocks of igneous origin : 



1. The parent rock of the serpentine. 



2. Hornblende granite, intrusive through the serpentine. 



3. Porphyrite, which was intruded generally along the 



southern contact of the serpentine with the sedi- 

 mentary slates, and with the fragments thus included 

 forms an ao'glomerate. 



4. The Camptonite dyke, which is much later in age, and, 



being a common associate of rocks of a different 

 character, is only doubtfully connected with the 

 others in origin. 



1 Ur. R. W. Ells. Ann. Rejit. Geol. Survey of Canada, 1S94, p. SO J. 



2 Ottawa Naturalist, Jan., 1901. 



