134 COAL-FIELD OF CLACKMANNANSHIRE. 



the opposite side of the slip. When dikes inter- 

 sect the strata, they generally only separate the 

 strata the width of the dike, without any disloca- 

 tion either up or down ; so that if a coal is inter- 

 cepted by a dike, it is found again, by running a 

 mine directly forward, corresponding to the angle 

 or inclination of the coal with the horizon. 



The three subordinate coal-fields, before mention- 

 ed, have all the same general characters ; but the 

 coals, and the strata which separate them, vary 

 sometimes in thickness. The distinct and lead- 

 ing characters of these three fields, is the coal 

 which is 9 feet thick, marked with a stronger line 

 than the other coals in the section. This coal is 

 alike thick in all the three fields ; is of the precise 

 same texture and quality ; has bituminous shale in 

 the roof, with numerous compressed impressions of 

 oyster shells, named, from their colour, Tobacco 

 Leaves by the miners, with regular bands and balls 

 of fine clay iron-stone. All the coals in the north 

 and middle coal-fields are very similar in quality, 

 and vary only a little in thickness ; whereas, in the 

 south coal-field, all the coals, except the 9 feet coal, 

 are thinner than in the other fields : and, in parti- 

 cular, the coal marked x, is about 6 feet thick in 

 the north and middle fields, and is composed of cu- 

 bical and splint coal ; whereas, in the south field, 

 the corresponding coal, marked x> is uniformly only 

 3 feet thick, without any splint coal, but is propor- 

 tionally richer, and of finer burning quality. All 



