358 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Mai'cll 13, 



rounded pebbles of light-coloured quartz. This slate is succeeded by- 

 thick beds of grey quartzite and hard olivaceous slates. These occupy 

 the river-section for about 700 yards^ or as far as the ''Falls," where 

 the river is thrown over a ridge of quartzite fifty-five feet in height ; 

 a small rill pouring in on the eastern side from a much greater eleva- 

 tion. Between the conglomerate and the waterfall, the quartzite con- 

 tains a few narrow strings of ankerite, and at the fall there is a group 

 of reticulating veins, some of them six inches in thickness. They 

 contain a little iron pyrites. These are the only indications of the 

 iron vein observed in this section ; and as the group of beds in which 

 it should occur is well exposed, it is probable that it is represented 

 here only by these small veinlets distributed over a great breadth of 

 rock, ilbove the fall the quartzite and slate continue to alternate for 

 a considerable distance ; the dip being generally to the southward, in 

 one place at as low an angle as 55°. About a quarter of a mile above 

 the fall, they are traversed by a dyke or mass of fine-grained horn- 

 blendic igneous rock. 



On the elevated ground, east of the Folly River, the vein is again 

 largely developed, and two excavations expose a part of its thickness 

 on the property of the Londonderry Mining Company. The excava- 

 tion nearest to the river shows a thickness of 1 90 feet of rock on the 

 south side of the vein. This consists of grey quartzite, olive slate, 

 and about three feet of black slate. These beds are traversed by a 

 few small strings of ankerite, which increase in dimensions on ap- 

 proaching the broken and irregular wall of the vein. About seventeen 

 feet of the south side of the vein consists principally of ankerite. Ad- 

 joining this on the north is red iron ore with nests of specular ore, 

 veins and blocks of ankerite decomposed in part to yellow ochre, and 

 fragments of rock. Ten feet in thickness of this red ore is seen without 

 exposing the north wall of the vein. 



On the surface in this vicinity are large fragments of brown haema- 

 tite, which mark the course of the vein. In the eastern excavation, 

 this mineral is seen in place near the surface and occupying fissures 

 in a fragment of quartzite. In this second excavation the red ore is 

 more largely mixed with the micaceous specular variety, and also in- 

 cludes large rounded blocks of ankerite and angular fragments of rock. 

 The width exposed here is thirteen feet, and neither wall is seen. The 

 ankerite is decomposed to the depth of eight feet. The same appear- 

 ance of transverse vertical layers seen at the Acadia Mine is observed 

 here, and is probably due to the same cause. 



Still further east, on the property of C. D. Archibald, Esq., and on 

 ground equally elevated, three excavations have shown a still greater 

 development of the vein. A trench fifty-three feet in length, and 

 nearly at right angles to the course of the vein, shows in its whole 

 length a mixture of red and specular ores with ankerite. Another 

 excavation ninety- five feet to the northward of the first, exhibits an- 

 kerite tinged of a deep red colour by peroxide of iron, and traversed 

 by reticulating veins of red iron ore. A third opening, 365 feet south- 

 eastward of the first, shows white and grey ankerite, having some of 

 its fissures coated with tabular crystals of white sulphate of barytes. 



