THE CANADIAN JOURNAL 



NEW SERIES. 



Nq. XIII.— JANUAEY, 1858. 



^ON TH:e PEOBABLE StrBDITISlON OF THE LAtJEEM- 

 TIAN HOCKS OF CANADA. 



BY SIR tVILLlAM E. LOGAT^, F. R. S., 



DIHECTOE GF THE GEOLOGICAL StJEVEX OV CAIfAt)!. 



'Read before the American Association for the Advancefnent tf 

 Science, at Montreal, August 14th, 1857. 



1 Lave already indicated tlie probable geparation of tbe Laurentian 

 i-oeks of Canada into two great groups : that characterized by the 

 presence of much lime and that without ; but from recent investiga- 

 tion, the result of which has just been repoi'ted to the Canadian 

 Grovernment, it appears to me almost certain that the former of these 

 two great groups will be capable of subdivision, and that some of its 

 bands of limestouo, with their associate strata, are of suiScient im- 

 portance to be represented separately on the map. Having followed 

 out one of these bands of limestone through all its windings, for a 

 distance of eighty miles, the object of the present paper is to exhibit 

 to the Section its geographical distribution, and the forms it presents 

 in the physical structure of the region which it characterises. WhM 

 -at first appear to be two bands of these limestones, emerge from be- 

 neath the Lower Silurian series in the township of Orenville, on the 

 Ottawa, and run into the interior parallel to one another, striking 

 N. N. E. They are about two miles separated from one another, and 

 feoth, with the gneiss between, dip in one direction, whi-ch is H.N/W^,, 



VOL. III. A 



