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part of which, according to Dr. Maton, v. 1. 107, rests on 

 a bed of sand now seventeen feet deep, it may have sunk 

 into spaces for springs, &c. and that at seventeen different 

 periods, between each of which there was time sufficient 

 for the forming of fresh wood and fresh clay, in adequate 

 proportion to the thickness of each stratum, as the sinking 

 of the wood was probably followed by something of an in- 

 undation, whether quick or slow. Thus the change of the 

 wood might be effected ; the lowest or oldest being nearest, 

 when compared with the rest, to perfect coal. The strata 

 here are, however, less dense and looser than that under 

 which the Northern or Newcastle Coals are formed ; conse- 

 quently it is a series pointing out something like a modern 

 formation, giving us apparently a hint of the commence- 

 ment of a more remote one. The cause, I think, may be 

 presumed adequate to the effect ; if we suppose a more or less 

 perfect communication (according to the time of the falling of 

 the first stratum) with the external southern aspect, the ef- 

 fects of wet and dry would rot the wood, and an evaporation 

 would more or less be carried on, so as to accomplish the 

 changes here seen ; the upper strata being least changed, 

 and only rotting by imbibing and evaporating moisture 

 night and day, winter and summer. The resinous or bitu- 

 minous parts have been more or less allowed to evaporate, 

 according to the pressure; at the surface but little, and at 

 the bottom scarcely at all, being out of the reach of per- 

 ceptible change ; and as it loses its most volatile principles, 

 the more durable woody principle, or caibon, will last for 

 ages, like a post charred to preserve it from the damp* 

 when put into the ground, which is so rendered extremely 

 durable. We are sure to find that the post rots where there 

 is most vicissitude of wet and dry, or nearly on the surface 

 of the ground, and sometimes the damps will penetrate and 

 rot the inside of the charred part which is itself almost in- 

 destructible. 



