144 COAL-FIELD OV CLACKMANNANSHIRE. 



that for this very obvious reason, that no mineral 

 whatever has been wrought to such an extent, and 

 in every direction, as coal ; for at whatever depth a 

 coal-mine is drained of its water, the mines are 

 wrought from that depth to the rise of the water-level 

 line, and each miner perseveres in carrying forward his 

 room or working place, until the coal meets the al- 

 luvial cover of the crop, or is cut off by a disloca- 

 tion of the strata. It is from this circumstance we 

 can state, in a decided manner, the absolute shape 

 of coal-fields. It is the opinion of many, that the 

 beds of coal contained in a coal-field are tabular 

 masses, which lie evenly between their bounding 

 planes, like a slab of marble ; and this no doubt 

 appears to be the case, if a partial and limited view 

 be taken of a bed of coal wrought upon a small 

 scale ; but to form an accurate conception of the 

 form of a coal-field, it must be viewed in its whole 

 extent, and in all its bearings, as pointed out and 

 particularly enforced by Professor Jameson, in his 

 Lectures. There are, I am informed, instances of 

 coal being found in the form of insulated tabular 

 masses ; but this occurs in another series of rocks 

 described by Werner, and not in the Independent 

 Coal-formation, of which we are now treating. The 

 Hamilton coal-field, according to what I conceive 

 of W erner's views, does not belong to the Indepen- 

 dent Coal- formation, but appears to be of a more re- 

 cent formation. The section, Fig. 1. Plate VII. 

 shews abrupt endings of the coal, without coming 



