No. 8.] VENNOR GALENA IN LAURENTIAN ROCKS. 461 



lead veins of the Laurentian rocks, are newer than at least the 

 Calciferous formation, and possibly than some of the formations 

 above it, thus extending considerably the area in which such 

 veins may by looked for." I need only add that my own obser- 

 vations fully support the view thus taken by Sir William res- 

 pecting both the character and age of these veins, and that 

 although I have considerably added to the lineal extent of this 

 great group of lodes and collected many further facts relative to 

 their conditions in the Laurentian strata, I can throw but little 

 additional light on their true ori2:in. 



As to the future prospects of the Ramsay lode, I may state 

 that little is to be expected either in depth, or in drifting in a 

 north-westward direction, and for two simple but potent reasons. 

 The Calciferous and Potsdam strata, which the lode intersects, 

 are comparatively thin outlying deposits towards the termination 

 of the great mass of the Silurian, which extends for miles to the 

 north-eastward and south-eastward. Consequently at a depth 

 not exceeding 100 feet, a shaft would probably enter the Lau- 

 rentian gneisses or limestones, probably the former, when the vein 

 might be expected to become unprofitable. The same would 

 happen in drifting on the lode in a north-westward direction, at 

 a very short distance. The only other course then left would be 

 its exploration in a southeastward direction, if this be practi- 

 cable, when there is no reason why the lode should not contain 

 as much if not more ore than in the spot where it was first mined. 

 There is perhaps, however, a possibility that higher members of 

 the Calciferous, or immediately succeeding formations of more 

 recent age, may cap over and conceal the lode in this direction. 

 I cannot state decidedly that the ore in this and similar lodes 

 would at once diminish upon entering the Laurentian, but simply 

 that what evidence has been fathered from the condition of the 

 lodes intersecting such strata in other localities in the same town- 

 ship, would point in this direction. On the other hand, the 

 galena lodes of Eossie in St. Lawrence County, N. Y., in the 

 Laurentian, have, to some extent at least, been profitably wrought, 

 and many of the same through Lansdowne, Loughboro' and 

 Bedford in similar strata, appear to be of greater or less 

 promise. Still the fact remains that in the latter localities the 

 lodes are no longer worked, while a number of them have been 

 abandoned as decidedly unprofitable. The Loughboro' mine, 

 near Indian Lake in Loughboro' township, is situated, perhaps, 



