456 THE CANADIAN NATURALIST. [Vol. vii. 



sequentiy examined these lodes, and published a short paper on 

 the Geology of Rossie. (Can. Nat. and Geol., new series, vol. 2., 

 p. 267 et seq.) Beyond these notices, nothing has been pub- 

 lished on this interesting and important subject. My own explora- 

 tions, however, now enable me to state with a still greater degree 

 of certainty, that all the galena lodes belong to a great belt or 

 zone of parallel fissures, which extends not only from Rossie in 

 New York to Bedford, but also to a irreat but unknown distance 

 beyond, in a general north-westerly direction. These lodes are 

 not of Laurentian age, as they extend up into the Potsdam and 

 Calciferous rocks ; or perhaps it would be more correct to state 

 that they extend, at any rate, from the Calciferous, through the 

 Potsdam, into the upturned edges of the Laurentian strata. For 

 we have abundant evidence to prove that these latter rocks had 

 assumed their present folded condition long before the deposition 

 of the former, and consequently at a still greater period prior to 

 the force or forces which have caused so extended a Assuring of 

 strata. It is not so clear, however, whether this force acted from 

 below upwards, or from the Calciferous downwards into the 

 Laurentian strata. Nor is it yet determined which rock is the 

 true source of the ores which now fill the fissures. What 

 evidence we have on these points, however, is instructive. We 

 find, for instance, that the lodes are, in some way or other, 

 connected with the junction or line of contact between the Silu- 

 rian and Laurentian formntions. This contact may be represented, 

 according to Mr. Alexander Murray, "by drawing a straight line 

 from about the middle part of Loughboro' Lake across the heads 

 of Knowlton and Beaver Lakes, to Round Lake in Belmont, a 

 small sheet of water a little beyond Belmont Lake, and then 

 another from Round Lake to the northern extremity of Balsam 



Lake There will, however, be several deviations from the 



regularity of the straight lines, occasioned by undulations in the 

 more ancient rocks, bringing them occasionally to the surface on 

 the south, while a number of outlying patches of the more recent 

 formations are spread over portions of the country to the north." 

 The junction of these two formations will be more clearly under- 

 stood by consulting the large colored geolouical maps published 

 by the Geological Survey of Canada, on which the Silurian is 

 represented by the dark blue color. Along this whole line, and 

 extending northward from it for twenty to forty miles through 

 the Laurentian strata, there occur equidistant and parallel fis- 



