Laurentian Magnetic Iron Ore Deposits. 135 



There is undoubtedly a non-conformity of the limestones with the magnetic 

 ore series or lower members of the Laurentian, but the relation of the Labrador 

 series to this limestone is by no means clear. 



We have, therefore, the following groups in ascending order : 



The Lower Laurentian Magnetic Iron Ore series. 



The Laurentian Sulphur Ore series. 



The limestones (verd antique marbles, plumbago, etc.), and the Labrador 

 series, or Upper Laurentian with its Titanic Iron Ores. 



The Laurentian Magnetite group is the lowest and the Labrador series the 

 highest, but the precise relations of the Sulphur Ore and Limestone series are 

 still undetermined. 



The Lower Group of the Lower Laurentian. 



This series of quartzites, Hornblendic gneisses and micaceous, garnetiferous 

 gneisses, with its beds of rich magnetite, occupies a comparatively limited area 

 as compared to that occupied by the other groups of the series. 



The mines at Mineville, in the township of Moriah, are located about 1,200 

 feet above the lake level, which is about 100 feet above the level of the sea. 

 These mines are located on two distinct horizons. The beds located on the 

 upper horizon are the "New Bed," "Barton Hill" and " Fisher Hill " mines. 

 Those of the lower horizon are the " 21," the " Old Bed " and " Cook's Shaft " 

 mines. 



The general pitch of the ore beds is to the west and northwest, where the 

 structure has not been complicated by folds, contortions or faults. 



It is, in many cases, scarcely possible to determine the direction in which the 

 beds pitch, but from all I can learn from careful observation, the deposits at the 

 lower horizon, or those of " 21 " and the " Old Bed " mine, are on a line of an 

 anticlinal fold, which has been complicated by faults. 



At the Cook Shaft we have clearly a monoclinal, pitching to the westward, as 

 we have in the upper workings of the New Bed, Barton Hill and Fisher Hill 

 mines. 



The only mines of note near the lake shore are the " Cheever " mine and the 

 continuation of the same bed in the Champlain and Essex Company's works, 

 located a little to the south of east from Mineville and north of Port Henry. 

 The geological connection between these deposits is not established, as there are 

 no large developments between these points. I am inclined to think, however, 

 that, from the saucer-shaped structure at the Cheever mine, there is a fault which 

 cuts off its connection with the geology to the west. The rocks between the Cheever 

 mine, which is at the lake shore, and Mineville, have in general a westward pitch. 

 This is demonstrated in the intermediate workings, as at Pilfershire (Lot 25, 

 Small's patent), and in some few other places where openings have been made. 

 Undoubtedly there are more iron ore horizons than these of Mineville and the 

 Cheever, as it may be found in any position within the limits of the Lower Lau- 

 rentian series ; but whether there is more than this horizon known within this 

 northeastern quarter of the township of Moriah, is still an open question. 



I am at present of the opinion that the horizons of the Mineville deposit are 

 repeated again by a fold or step fault, or by both, and reappear at and in the 

 vicinity of Pilfershire, and along the line of the outlet of Barton pond, which 

 flows into Mill brook. 



The region east and south of Mineville is so completely covered by glacial 

 drift, that it is impossible to trace the succession of rocks with precision. 



We have the Lower Laurentian rocks in some workings with a pitch to the 

 eastward and southward, overlaid with glacial debris, and, therefore, beyond 

 these workings we have no data. 



