HISTORY OF STAFFORDSHIRE. [131 



some species ; but in the best kinds there is too little argillaceous 

 matter to consider it as the basis of the composition. The most 

 generally received opinion is, that coal is formed from vegetable 

 matter. Dr. Darwin says there is reason to believe that bitumen 

 or petroleum, with jet, amber, and all the fossil coal in the world, 

 owes its inflammable part to the recrements of destroyed forests of 

 terebinthinate vegetables so important to the present race of 

 mankind has been this vegetable secretion. The incumbent strata 

 of coal, sand, iron, clay, and marl, are chiefly the products of ve- 

 getable organization, changed in the long progress of their de- 

 composition ; and all these solid parts of the earth have been thus 

 fabricated from their simpler elements by vegetation, and by animal 

 life. Mr. Keir says, " but we know no similar fact or experiment, 

 from the analogy of which we can infer the possibility of such con- 

 version." He believes, that in all or most coals, the vestiges of 

 vegetable fibres are to be seen ; " not, however, forming the whole 

 substance of the coal, but interspersed as thin laminae between 

 the thicker and more shining bituminous layers of the coal." We 

 know also, that in all coal-mines, the superincumbent strata of 

 clunch and rock, contain abundance of vegetable impressions, 

 chiefly of reeds and broad leaves, like the stems and foliage of 

 aquatic plants. The substance or body of the reed is sometimes 

 rock and sometimes iron ore, audits surface only is covered with a 

 thin coat of coal, as if the rocky or ferruginous matter which filled 

 up the space which had been occupied by the decayed vegetables, 

 had, by the contraction of drying, left an interval which was after- 

 wards filled up by a bitumen, whether that bitumen came in a liquid 

 form or in the state of a distilled vapour, or whether it was the 

 remaining oil and resin of the plant hardened by age, or by 

 absorption of air, Some kinds of coal are entirely free from 

 vegetable vestiges, and are an uniform, compact bitumen ; it 

 therefore seems most probable, that the vegetables have done 

 little more towards the formation of coal, than to furnish a conve- 

 nient space for the insinuation of the ejected, or distilled bitumen. 

 But in whatever manner coal was formed, it is very certain that it 

 was formed all over the country together, (where now existing) 

 and that its irregularity has been caused by internal convulsions 

 of the earth, which convulsions broke through and raised the strata 

 of lime-stone into the form of mountains, and which also raised the 

 superincumbent strata of which coal is one, and left it in the form it 

 now appears, except the softer parts near the surface, which have 



