TIIK l-AUKENTIAN. 33 



series, wlicreas the true aqueous roeks of tliis scries would afford 

 better terms of comparisou with other districts than merely igneous 

 masses or beds. A similar objection, I think, applies in some degree 

 to the name Norian, as more recently given by Hunt; and I have no 

 doubt, from my own observations in the typical districts, that Logan's 

 division must stand, thou,2;h perhaps it would be well to separate the 

 lower gneiss from the remainder of his Lower Laurentian, and to re- 

 cognise a Lower, Middle, and Upper group, all of which are distinctly 

 crystalline rocks.* The upper member, as developed in the west, 

 should, I think, include some of the crystalline rocks which have 

 been classed as Iluronian, and which seem to fill part of the gap 

 between the latter and the Lower Laurentian in the regions further 

 east.f This view will in any case afford better means of comparison 

 with the Laurentian of other districts, and the occurrence of masses 

 of binary granite and syenite in the Lower group and of labradorite 

 in the Upper need not interfere with such comparisons, though it is to be 

 observed that in the Upper member plagioclase felspars are much more 

 abundant than in the Lower. Prof. Bonney has some very judicious 

 remarks on this in his Anniversary Address before the Geological 

 Society in 1886. 



Whatever views may be entertained as to the origin of these old 

 rocks, no one who has studied the typical districts of the Ottawa 

 Kiver can doubt for a moment that they are regularly bedded deposits, 

 and that in the Middle Laurentian those conditions which in later 

 periods have produced beds of limestone, sandstone, iron-ore, and even 

 of coal, were already in operation on a gigantic scale. \ At the same 

 time it may be admitted that some areas of the lower gneiss may be 

 cooled portions of an original igneous mass, and that many of the 

 schistose rocks may be really bedded igneous materials. 



Turning now to the Atlantic coast, the greatest area of Laurentian 

 rocks is that forming the nucleus of the Island of Newfoundland, lu 

 the northern part of that island the absence of the great crystalline 



* Tlie two principal members linve been named respectively the Ottawa and Grcn- 

 ville .series. The third, or upper member, in Logan'-s typical district has been separated 

 as the Norian scries by Hunl; and by Selwyn (Reports Gcol. Survey of Canada, 

 1879-80) is regarded as mainly composed of igneous rocks. In the JIaritinie Provinces, 

 as we shall see, only two members have been recognised. 



t Dr Bigsby, " On Lake of the Wo,)ds," Journal of (leol. Society. ISol-'.' ; Dr (i. :^I. 

 Dawson, Keport on 49th Parallel, 187,5 ; Mr Lawson, Reports Geol. Survey of t'anada. 

 1885. The latter has proposed the name " Keewatin " for some of these rocks in tlio 

 west. 



t Q. J. G. S., vols, xxiii., xxv., xxxii., xxxv. In these papers I have set forth niit 

 iTierely the evidence for the organic character of /ur.txDi, but for that of the I,;iureiitian 

 limestones and graijhites and phosphates in general. 



C 



