No. 8.] VENNOR — GALENA IN LAURENTIAN ROCKS. 455 



NOTES ON SOME OF THE GALENA OR SULPHURET 

 OF LEAD DEPOSITS CONNECTED WITH THE 

 LAURENTIAN ROCKS OF ONTARIO. 



By He.nky G. Vennor, F. G. S. 



Galena or sulphuret of* lead is so often found associated with 

 the crystalliue limestones of the Laurentian, that an idea seems 

 to prevail that, like the magnetic oxide of iron, it may specially 

 characterize one or more of these bands. But recent investiga- 

 tions, while furnishing conclusive evidence that such is the case 

 respecting the latter mineral, appear to show clearly the contrary 

 concerning the former. The origin of these two mineral deposits 

 is very dijfferent. The magnetic oxide of iron is now proved to exist 

 for the greater part in the form of beds, or interstratified masses, 

 in certain horizons of the gneiss and limestone series ; and in a 

 recent Report of the Geological Survey, I have shown that, in 

 Frontenac and Lanark Counties, not less than three horizons of 

 iron ore may be identified, which bear fixed relations to three 

 seperate bands of limestone. The galena, however, does not 

 occur in the form of sedimentary deposits, but always in true 

 fissure veins, which traverse great areas in the Laurentian rocks. 

 Consequently the occurrence of this ore in veins in any of the 

 bands of limestone is merely accidental, or, in other words, is 

 simply owing to these bands in parts of their distribution being 

 crossed by what may correctly be designated as zones of dis- 

 turbance. It is the object of the present paper to show that 

 these zones are accompanied by great parallel breaks or fissures 

 and displacements of the strata, which traverse the country in 

 straight lines for great distances. ^ 



The galena deposits of Lansdowne, Storringtou, Loughboro', 

 and Bedford have been long known, and many localities in these 

 townships where the ore has been mined, have been mentioned 

 in the Reports of the Geological Survey. In one of these Re- 

 ports, for the year 1858, Sir W. E. Logan, in referring to the 

 galena lodes of Lansdowne and Bedford, .suggests the probability 

 of their forming a part of the same group as the lead-bearing 

 lodes of Rossie, in St. Lawrence County, N. Y. In this con- 

 jecture he was supported by Mr. Thomas Macfarlane. who sub- 



