138 SCIENCE IN SHORT CHAPTERS. 



and the position of many of the vegetable remains associated 

 with coal. 



There is another serious objection to this theory that I have 

 not seen expressed. It is this : Rivers bringing down to their 

 mouths such vegetable deltas as are supposed, would also bring 

 considerable quantities of earthy matter in suspension, and this 

 would be deposited with the trees. Instead of the 2 or 3 per 

 cent, of incombustible ash commonly found in coal, we should 

 thus have a quantity more nearly like that found in bituminous 

 shales which may thus be formed viz. from 20 to 80 per cent. 



The alternative hypothesis now more commonly accepted 

 that the vegetation of our coal-fields actually grew where we 

 find it is also refuted by the composition of coal-ash. If the 

 coal consisted simply of the vegetable matter of buried forests 

 its composition should correspond to that of the ashes of plants ; 

 and the refuse from our furnaces and fireplaces would be a 

 most valuable manure. This we know is not the case. 

 Ordinary coal-ash, as Bischof has shown, nearly corresponds 

 to that of the rocks with which it is associated ; and he says 

 that " the conversion of vegetable substances into coal has been 

 effected by the agency of water ;" and also that coal has been 

 formed, not from dwarfish mosses, sedges, and other plants 

 which now contribute to the growth of our peat-bogs, but 

 from the stems and trunks of the forest trees of the Car- 

 boniferous Period, such as Sigillarice Lcpidodendra, and 

 Coniferce.* All we know of these plants teaches us that they 

 could not grow in a merely vegetable soil containing but 2 or 3 

 per cent, of mineral matter. Such must have been their soil 

 for hundreds of generations in order to give a depth sufficient 

 for the formation of the South Staffordshire 10-yard seam. 



All these and other difficulties that have stood so long in the 

 way of a satisfactory explanation of the origin of coal appear to 

 me to be removed if we suppose that during the Carboniferous 

 Period Britain and other coal-bearing countries had a con- 

 figuration similar to that which now exists in Norway viz. 

 inland valleys terminating in marine estuaries, together with 

 inland lake basins. If to this we superadd the warm and 

 humid climate usually attributed to the Carboniferous Period, 

 on the testimony of its vegetable fossils, all the conditions 

 requisite for producing the characteristic deposits of the Coal 

 Measures are fulfilled. 



* Hull, " On the Coal-fields of Great Britain." 



