1853.] 



DAWSON ON THE ALBERT MINE. 



113 



Fig. 5. Section of 

 the beds at the 

 East end of Al- 

 bert Mine. 



able dip to the S. 5° E., at an angle of 69°. The appearance presented 



at the time of my visit in the extreme end of the most advanced level, 



is represented in fig. 5, where it will be observed 



that the S.E. wall still shows indications of the 



prevailing contortions of the beds, and of the 



manner in which these cause the ends of strata to 



abut against the coal. 



At this place, an exploratory level, driven to 

 the S.E., shows a series of bituminous shales, 

 with bands of ironstone, dipping regularly to the 

 south-eastward. I could not, in any part of the 

 mine, find beds corresponding to the Stigmaria- 

 underclay of ordinary coal-seams, though on the 

 S.E. side some of the beds are of a more compact 

 and purely argillaceous character than those on 

 the N.W. side, or roof, of the seam. The iron- 

 stone bands and fish-bearing shales are, however, 

 not very dissimilar from those in some coal-mea- 

 sures of the ordinary coal-formation. They present no indications 

 of metamorphism or of the passage of heated vapours, and all their 

 appearances show that their bituminous matter has resulted from 

 the presence of organic substances at the time of their deposition. 



It is evident that all the above phsenomena can be explained on 

 the supposition that this coaly mass occupies a fissure running along 

 an anticlinal bend of the strata ; and that, apart from the character 

 of the mineral and the containing beds, this would be the most 

 natural explanation. On the other hand, when we consider the 

 contorted condition of the beds, indicating disturbance when in a soft 

 state, and the slickenside joints, pointing to subsequent shifts, we 

 cannot refuse to admit that a conformable bed of true coal, if subjected 

 before and after its consolidation to such movements, might present 

 all the appearances of complication and disturbance observed in this 

 mass, more especially if originally of small extent, and thinning out 

 toward the edges. On this view we should have to suppose, — 1 . Dis- 

 turbance and contortion of the beds while soft, and, at the point in 

 question, a regular and somewhat abrupt arching of the beds ; 2. A 

 fault throvring down the south side of the arch along a line, coinciding 

 in part of its course vdth the highly inclined underside of the coal at 

 the north side of the arch ; and 3. Removal of the upper part of the 

 north side of the arch by denudation. Fig. 6 represents the appear- 

 ances which would thus be produced, and it will be seen that they 

 very closely correspond with the present condition of the deposit, not 

 excepting its thinning toward the surface. If this be the true 

 explanation, it is probable that the sunken south side of the bed has 

 not yet been reached in the excavations. It might, however, in 

 approaching it from above, show a succession of wedge-shaped 

 included masses of rock or "horses," one of which I saw in the floor 

 of the lowest level. On this view, also, the " Jog " or fault, above- 

 described, may be a lateral bend received by the bed in the original 

 contortion of the strata ; and at this point the straight fracture, pro- 



