THE 



CANADIAN NATURALIST. 



SECOND SERIES. 



i^*- 



CONTRIBUTIONS TO LITHOLOGY.* 



By T. Stbrry Hdnt, M.A., F.R.S. ; of the Geol. Survey of Canada, 



III. On Some Eruptive RocKs.f 



In Silliman's Journal for March 1860 (2nd, xxix, 282) there is a 

 short note, pointing out the existence, in the vicinity of Montreal, 

 of several interesting classes of eruptive rocks, including quartzi- 

 ferous porphyries, trachytes, phonolite, dolerites, and diorites. It 

 is proposed in the third part of the present paper to describe the 

 results of some chemical and mineralogical examinations of these 

 rocks, and to give by way of preface a description of their geogra- 

 phical distribution and geological relations. They may be con- 

 sidered geographically as belonging to two groups ; of which the first 

 and more important for the number and variety of its rocks may be 

 conveniently described as the Montreal group. It consists of a 

 succession of intrusive masses along a belt running nearly trans- 

 verse to the undulations of the Notre Dame Mountains, which are 

 the prolongation of the Appalachians into eastern Canada. Com- 

 mencing at Shefford Mountain, an isolated trachytic mass not far 

 removed from the western base of the Notre Dame range, we find, 

 going westward, the detached hills known as Yamaska, Rouge- 

 mont, Rouville or Beloeil, Montarville or Boucherville, Mount 

 Royal or Montreal, and Rigaud Mountains ; the last being dis- 

 tant about ninety miles from Shefi'ord. Brome Mountain, which 



* Concluded from page 36. 



t From Sillima7i's Journal^ vol. xxxviii. 



Vol. I. L No. 3. 



