No. 1.] SELWYN — THE QUEBEC GROUP. 29 



ical investigation both seem to point very closely to this as the 

 true explanation of their origin. That they are eruptive rocks 

 is held by nearly all geologists who have carefully studied their 

 stratigraphical relations. But I am not aware of any one having 

 suggested that they are the products of volcanic action in the 

 Laurentian or perhaps lower Huronian epoch ; doubtless, as 

 Mr. Leeds says ^'profoundly metamorphosed'^ as of course they 

 would be from having suffered all the physical accidents which 

 have resulted in producing the associated gneisses quartzites, 

 dolomites, serpentines and schists. 



When we recall the names of Dahl. Kerulf and Torrell in 

 Norway, Maculloch and Geike in Scotland, Emmons, Kerr, Hitch- 

 cock, Arnold Hague, and others in America, all of whom consider 

 these norites as of eruptive origin, we may well pause before ac- 

 cepting Dr. Hunt's conclusions respecting them, and that they 

 should often appear as " bedded metamorphic rocks" (the opinion 

 expressed respecting those of Skye by Prof. Haughton of Dublin) 

 is quite as probable as that we should find the mineralogically 

 similar dolerites occurring in dykes and bosses and in vast beds 

 interstratified with ordinary sedimentary deposits of clay, sand, 

 etc. 



In conclusion I may say that I fail to see that any useful pur- 

 pose is accomplished, in the present stcige of our knowledge of the 

 stratigraphical relations of the great groups of rocks which under- 

 lie the lowest known Silurian or Cambrian formations, by the in- 

 troduction of a number of new names such as those proposed by 

 Dr. Hunt for systems which are entirely theoretical, in which 

 category we may in my opioion include the Norian, Montalban, 

 Taconian and Keeweenian. These, one aud all, so far as known, 

 are simply groups of strata which occupy the same geological 

 interval, and present no greater differences in their physical and 

 mineralogical characters than are commonly observed to occur 

 both in formations of the same epoch in widely separated regions, 

 and when physical accidents, such as contemporaneous volcanic 

 action or subsequent metamorphism have locally affected the 

 general character and aspect of the formation within limited 

 areas. 



No better instances of such differences could be cited than the 

 Mesozoic and Carboniferous formations of British Columbia and 

 those of the same periods in Eastern America, and the Silurian 

 and Cambrian formations of Australia, Europe and America. 



