4:62 THE CANADIAN NATURALIST. fVol. Vli. 



on one of the best tested lodes in this group, and it furnishes us 

 with an example of how the galena may be largely replaced by 

 blende as we descend into the Laurentian strata. In Bedford 

 though galena was found in large masses at the surface of a 

 number of the lodes, it beyond a doubt diminished in depth. 

 Again, in the great series of lead-bearing veins in Tudor, Lake 

 and Methuen in Hastings and Peterboro' Counties, astonishingly 

 large and pure masses of ore were found in many instances imme- 

 diately at the surface of the lodes, but rapidly diminished in 

 every instance in descending. The shaft of Messrs. Hill & 

 Kershaw in the township first named was in my opinion one of the 

 best tests made in this section of country. It was sunk on a 

 beautifully defined lode, cutting the grey limestone or calc schist 

 of the Hastings series, to the depth of 130 feet, but long before 

 reaching this depth the ore had ceased to occur in remunerative 

 quantity, although the vein continued to descend as well defined 

 as at the surface. 



In conclusion then I can only express the opinion that these 

 Galena lodes in the Laurentian system are merely the remnant 

 of lodes which had their greatest development in the rocks of the 

 Potsdam and Calciferous, both of which formations have been 

 extensively removed by denudation. 



