THE MONTEREGIAN HILLS 243 



relationship, however, constituting as they do a distinct and 

 remarkable petrographical province, such a name is required. I 

 propose to call them the Mojiteregian Hills, deriving their name 

 from Mount Royal ("Mons Regius"), which may be taken as 

 their type, being as it is the best-known member of the group. 



There are certain other hills which have been considered by 

 former workers in the geology of this district to belong to this 

 group. Thus Logan thought that Rigaud Mountain, situated 

 near the margin of the plain, by the river Ottawa, about forty 

 miles west of Mount Royal, was "probably connected with" the 

 series.^ Ells ^ also included Mont Calvaire, a large, low mass 

 which rises from the plain immediately to the north of the Lake 

 of Two Mountains, near the junction of the Ottawa and the St. 

 Lawrence. 



Ells also refers to " the hills on the west side of Memphre- 

 magog lake and to the northeast toward the Chaudiere river and 

 beyond" as bearing a marked resemblance to the rocks of 

 Mount Royal, Yamaska, etc., and as probably being of the same 

 age.3 



In a careful study of Rigaud mountain, recently completed 

 by Mr. Leroy,'* of this universitv, it is shown that the rocks con- 

 stituting this mountain are different in character from those of 

 the Monteregian hills, being composed of a reddish hornblende 

 syenite and a quartz-bearing porphyry. These rocks, however, 

 were found to be identical in character and composition with a 

 great area of syenite, cut by porphyry, mentioned by Logan as 

 occupying some forty square miles in the townships of Chatham 

 and Grenville on the margin of the Laurentian plateau, a few- 

 miles to the north of Rigaud mountain. Owing to the drift 

 which mantles this district, the actual contact of the igneous 

 rock of Rigaud mountain and the Paleozoic strata of the plain is 



^ Geology of Canada, 1863, p. 9. 



^ " Report on a Portion of the Province of Quebec," Ann. Rept. Geol. Surv. of 

 Canada, Vol. VII, Part J, 1896. 



3 Eastern Townships Map (Montreal Sheet), Ann. Rept. Geol. Surv. of Can- 

 ada, Vol. VII, Part J. 



'■Bull, of the American Geological Society, Vol. XII, 1901. 



