588 THE UPPER SILURIAN. 



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

 more largely mixed with the micaceous specular variety, and also 

 included large rounded blocks of ankerite and angular fragments of 

 rock. The width exposed here was thirteen feet, and neither wall was 

 seen. The ankerite is decomposed to the depth of eight feet. The 

 same appearance 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, showed in its whole 

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

 excavation, ninety-five feet to the northward of the first, exhibited 

 ankerite 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, showed white and gray ankerite, having some of 

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

 The walls of the vein were not seen at this place ; but 150 paces south 

 of the first trench a thick dike of greenish igneous rock, apparently a 

 very fine-grained greenstone, appears, with a course of S. 102° W. 

 This dike was not seen westward of this place, but it can be traced for 

 a considerable distance to the eastward. In the Mill Brook, two miles 

 east of Folly River, it appears in connexion with a bed of black slate 

 near the margin of the metamorphic system, and probably a continuation 

 of that seen in a similar position in the Folly and Great Village Rivers. 

 At the Mill Brook the dike is about 100 feet in thickness. 



In the bed of the Mill Brook, the vein is seen in the form of a 

 network of fissures chiefly filled with ankerite ; and iff its eastern bank 

 it attains a great thickness. In the bank of another brook still further 

 to the eastward, and in the same line of bearing, it appears to be of 

 large dimensions, and contains abundance of red iron ore and red 

 ankerite. I have not traced it further to the east, but I have no doubt 

 of its continuance to a great distance in that direction. 



The geological history of this deposit embraces the following 

 occurrences : — lsf, The formation of a wide irregular fissure, along a 

 great part of the length of the Cobequid Mountains. 2dly, The filling 

 of this fissure with a molten or softened, and partially even sublimed, 

 mass of ferruginous and calcareous matter, presenting, as I think, an 

 evident illustration of the igneous formation of a vein of calcareous, 

 magnesian, and ferruginous carbonates. 3dly, The breaking up of the 

 vein thus formed by cross-fractures and faults. 4M/y, The partial 

 roasting of its contents by heat, so as to produce the red ores, which 



