20 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [NoV. 21, 



various bands of limestone and interstratified courses of coal and 

 iron-ore is admirably exposed in the beds of some of the watercourses 

 which flow from the loftier hills of older rocks*. 



Upon the only instructive traverse which we made, and to which 

 we were conducted by Mr. Slimon, viz. up the Coal Burn and along 

 the steep banks of the Poniel Water, which flow through grounds 

 now occupied by the productive coal and iron works of Brockley, &c., 

 we were highly gratified in seeing a splendid development of lime- 

 stones, shales, sandstones, coal, and ironstone, a precise account of 

 which and an accurate register of the fossils in each zone are much 

 to be desired. "We examined the so-called '* black band" of iron- 

 stone at Coal Burn (see Appendix, p. 25), and found it to be asso- 

 ciated with an indurated bituminous shale, which in Staflbrdshire 

 would be called *' black bat." The strata being very slightly in- 

 clined, the ironstone (8 inches thick) is worked by a gallery on the 

 side of the slope. In this locality the black band dips under a suc- 

 cession of strata of shale and sandstone, to which five seams of coal are 

 subordinate as well as one band of limestone. On the other hand, the 

 black band is here underlaid, as seen indeed in the open sections of 

 the watercourses before alluded to, by a much thicker succession of 

 similar shales and sandstones, including seven seams of coal and three 

 limestones. The lowest of the latter is a hard, concretionary, nodular, 

 white limestone, which immediately lies upon the Old Red Sand- 

 stone ; but no fossils have yet been found in it. The massive and 

 thick-bedded limestone, however, which overlies it, with the interven- 

 tion of some sandstone only, is laden with the large and small Pro- 

 ducti, a profusion of Encrinites, and many characteristic shells, some 

 of which are also found in the limestone near the top of the series. 



As Mr. Slimon has obliged me by preparing a working section of 

 the beds passed through in this tract of Coal Burn and Brockley, and 

 another of the Auchenheath Pits, situated on the opposite or northern 

 basin, and not far from the junction of the Nethan with the Clyde 

 (see Appendix, p. 25), the geologist who compares them will see how, 

 with a strong general petrographical resemblance, the order of the 

 carboniferous strata on the other side of the dividing Old Red of 

 Lesmahago is distinguished from that upon the south flank of the 

 same formation ; particularly in the much fuller development of 

 strata above the "black band " of ironstone. At Auchenheath the 

 shafts pass through a much more copious series of sandstones, shale, 

 and limestone before that iron- ore is reached; there being no fewer 

 than five calcareous zones above it. For, whilst in a much less ver- 

 tical space in the Coal Burn tract there are five seams of coal above 

 the black band, the very deep sections of Auchenheath there present 

 three seams of coal only superior to that ironstone. If it be objected 

 that the black band is merely a casual and accidental layer of rich iron 

 ore, and that when these fields shall have been elaborately worked out, 

 similar ore may be found to exist in more courses than one, and at 

 vari(jus levels — a feature which is by no means improbable, — still in 

 reference to the very limited area now under consideration, where the 



* A notice of the Lesmahago and Douglas Coal-field was read by Mr.Bryceat the 

 British Association Meeting at Edinburgh ; see Brit. Assoc. Rep. 1850, Sect. p. 71. 



