G, H. Kinahan — Irish and Canadian Rocks, Compared. 165 



granitoid gneiss very like some of those of Galway, Mayo, and 

 Donegal ; this is a rock intermediate in structure between those just 

 mentioned in Ontario and the coarse gneissic granite of Chicoutimi/ 

 Mont Calm, etc., of the province of Quebec ; these rocks apparently 

 all being more or less similar in their constituents, but having been 

 subjected to different degrees or periods of metamorphism. 



Here in connection with the Chelsea district may be mentioned 

 the schistose rocks between the highland and Chelsea settlement ; as 

 with them there are calcareous and allied rocks exactly similar to 

 rocks in the *' Ophiolite and Dolomite series " of the Twelve Pins or 

 Benuabeola district, co. Galway.'^ These Irish rocks have been sug- 

 gested by William King, Galway, to be of Cambrian age, while my 

 examination of the district seems to go to confirm this opinion.^ 



Before proceeding further, it appears necessary to mention some 

 peculiar Irish calcareous rocks. These are found at the base of the 

 Lower Carboniferous Sandstone, Co. Clare, at or near the base of 

 the Devono-Silurian rocks of Mayo and Galway, and at different 

 horizons in the Cambro-Silurians and Cambrians of Donegal, 

 Sligo, Mayo, Galway, Waterford, Wexford, and Wicklow. These 

 calcareous rocks are more or less intimately connected with basic 

 eruptive rocks and to me appear to be adjuncts of vulcanicity.* 

 In the township of Buckingham and elsewhere in Ottawa county 

 there are apatites (phosphate of lime), that make very like the 

 above-mentioned Irish Cambro- Silurian and Cambrian (?) limestones 

 as they are associated and more or less intimately connected or 

 entangled with the basic eruptive rocks. In connection with these, 

 it may perhaps be allowable to suggest, that originally they possibly 

 were carbonates ; but that in some way, not yet explained, but at 

 the same time being an adjunct of metamorphism, they were 

 changed into the phosphate. 



The rocks which par excellence are classed as Laurentians belong 

 to the lithological groups for which I have proposed the names 

 '•' Gneissic Granite or Granitoid Gneiss " and " Gneiss series " ; while 

 the Huronian rocks par excellence belong to the group called 

 "Schist series" and " Sub-Metamorphic rocks." ^ In these general 

 classifications, however, there are exceptions ; because, as in Ottawa 

 county, there are included in the tracts at the present time mapped 



1 Some of these rocks I learn from Dr. George Dawson, during last summer's 

 explorations, have been proved to belong to the Laurentians and not a separate 

 group. 



2 Geology of Ireland, chapter i. p. xxi. 



3 These rocks were suggested by the late Sir R. I. Murchison to be Laurentians ; 

 he however subsequently changed his opinion. In the late proposed classification of 

 the West Galway rocks, these have not been included in the so-called Archaean 

 rocks ; that distinction being given to the more metamorphosed, but younger rocks 

 in the country to the southward ;— rocks that have been proved by thek fossils to 

 be of Cambro- Silurian age. 



* Geol. of Ireland, chap. xii. p. 194. 



5 Geol. Ireland, chap. x. p. 177. As a rule the Huronians seem to belong to the 

 " Schist series," but some of the Huronian limestones and associated rocks between 

 Port Arthur and the Rat Portage belong to the rock called by Indian geologists 

 " Sub-Metamorphic rocks." Some of these limestones are very little altered. 



