THE MONTEREGIAN HILLS 245 



highly altered rocks. Many of them are altered diabases/ In 

 other cases the alteration is so far advanced that it is impossible 

 to determine the character of the original rock. Many of them 

 have been completely altered to masses of serpentine. Nephe- 

 line-syenites, essexites, and similar rocks have not as yet been 

 found anywhere in this chain of hills. A series of dyke rocks 

 from Lake Memphremagog, examined by Marsters,^ were found 

 to be chiefly granites and lamprophyres, with one typical camp- 

 tonite. It would seem therefore, that while our knowledge of 

 these hills is as yet very imiperfect, the evidence at our command, 

 so far as it goes, points to them as belonging to a group quite 

 distinct from Mount Royal and its associates. The petrograph- 

 ical province of the Monteregian hills may therefore, in the pres- 

 ent state of our knowledge, be said to comprise only the eight 

 mountains enumerated on p. 240, together with the consanguine- 

 ous dykes which at many points are found cutting the rocks 

 of the surrounding plains. 



The first description of these hills was that given by Logan 

 and Hunt in the early years of the Canadian Survey. To Hunt 

 especially we owe a somewhat extended description of the petrog- 

 raphy of the group and a number of chemical analyses, more 

 especially of the constituent minerals of certain of the rocks. 

 These descriptions are, however, very general and often very 

 imperfect, as must necessarily have been the case before the 

 introduction of modern petrographical methods. Nor were cer- 

 tain important petrographical relationships observed which have 

 in later times come to be recognized. This early work, how- 

 ever, is of great interest, and in case of three of the mountains 

 almost all the information which we have even at the present 

 time, is derived from those early studies. The results of this 

 work were brought together in the Geology of Ca7iada, published 

 by the Geological Survey of Canada in 1863, and are to be found 

 on pp. 655—70. During the thirty years following the appear- 

 ance of this volume, only three papers containing additional 

 information concerning these rocks appeared. These were by 



^ F. D. Adams, Ann.Rept. Geol. Surv. of Canada^ 1880-81-82, pp. 12-13 A- 



^American Geologist, ]u\y, 1895. 



