128 LOWER PENINSULA. 



to bake in tlic furnace, renders a breaking up of the half-melted 

 mass necessary to the securing of a sufficient draught. This is 

 remedied by setting the bars of the grates wider apart than in 

 those intended for the use of hard coal. By distillation at red heat, 

 the coal gives off 44 per cent of volatile matter. 



The strata beneath the coal in some of the borings just recorded 

 are found to be arenaceous shales and fire-clay, while in others the 

 coal was directly underlaid by a sand rock. Prof. Winchell terms 

 this sand rock, Parma sandstone, asserting that, in this position, a 

 large body of sand rock is invariably deposited throughout the 

 coal area of Michigan. Such regularity in the sequence of strata 

 does not exist in the coal formation. The beds in it are usually of 

 local extent, so that a position which in one place is occupied by 

 a shale bed may in a neighboring locality be filled by a ledge of 

 sand rock. The whole series is a constant alternation of shale and 

 sandstone beds, and every natural or artificial section teaches us 

 that an immense variety exists in this alternation. The deeper part 

 of the formation incloses several heavy sand-rock beds, which in 

 lithological characters are almost alike, so that in the limited ex- 

 posures presented to our view, the determination of the exact rela- 

 tive positions of . such beds becomes practically impossible. In 

 case we adopt this Parma sandstone, we will rarely have an oppor- 

 tunity to identify it with any degree of certainty. 



Two miles west of the Woodville coal mine, we find on Sandstone 

 Creek, close to the Michigan Central Railroad, another abandoned 

 mine. The surface rock is a soft dark shale with concretions of 

 kidney ore and iron pyrites, which latter often represent trunks of 

 Stigmaria. The coal seam, a little over 3 feet in thickness, had 

 only this soft shale for a roof. The mining therefore required too 

 costly timbering, and was consequently abandoned. On the slop- 

 ing hillside, north of the mine, at the foot of which the shales are 

 well exposed in the creek bed, and at a higher level, a patch of sub- 

 carboniferous limestone is found, apparently in undisturbed posi- 

 tion ; the top of the hill is formed by drift. This position of the 

 strata is decidedly abnormal, and one or the other of the rocks 

 must be dislocated ; but every thing is so covered up by drift 

 and sod, that it can not be told, from the visible surface expo- 

 sures, which of the two is in its place and which dislocated. Nu- 

 merous similar abnormal positions of the strata can be noticed 



