197 



being shallower tliere, and tlius more capable of being acted on by 

 solar and atmospheric influence, — but also from the subterranean 

 heat being there more intensely felt or more frequently evolved. 

 The same theory might account for the formation of limestone 

 in the upper part of the basin, though in proportion to the dis- 

 tance between the subterranean heat and tlie water, the precipi- 

 tates of lime would become less abundant and less frequent ; a 

 consideration which would explain why the five or six beds of lime- 

 stone that occur in the district, are all situated in the lower half of 

 the basin. 



With regard to the origin of the co«/-seams, it was observed, 

 there could be no doubt of their having been formed from ac- 

 cumulations of vegetable matter, which, at diflFerent periods, had 

 been drifted from a distance. The fact of these accumulations ha- 

 ving taken place at the bottom of the same sea or aqueous medium 

 in which the other strata of the basin were successively deposited, 

 seemed to be placed beyond dispute, by the discovery in the sub- 

 stance of the coal itself, and about four inches below the top of a 

 seam of coal, — of quantities of the teeth, bones, and scales of fish. 

 These remains belong to the same species, the remains of which 

 had been found in the shalbs of this coal-field by Lord Greenock, 

 and in the Burdiehouse limestone by Dr Hibbert. 



The vegetable matter which formed most, if not all, of the coal- 

 seams of the district, appeared to have been drifted from the west 

 or north-west, because in these directions the seams get gi-adually 

 thicker. 



As all the vegetables found in the coal-seams and adjacent shales 

 are terrestrial, it seemed probable that they had been torn oflF or 

 swept away from their native sites by periodical inundations : — 

 that they had been carried out into a great lake or estuary, where, 

 after floating about for a considerable time, they subsided in tran- 

 quil waters, but not before parting with the clay and other eai'thy 

 matters attached to their roots, and not before the sediment carried 

 off by the inundation, and mechanically suspended in the water, had 

 time to subside. It was inferred from this circumstance, that be- 

 neath every seam of coal there ought to be a bed of fire-clay, — an 

 inference which agrees with the fact. 



After these vegetable accumulations had taken place, and pro- 

 bably after all the other strata of the basin were deposited, the 

 entire series of rocks had evidently been operated on by some 

 powerful agent, so as to give to each its peculiar crystalline struc- 



