150 COAL AND COAL-FOKMATIONS. 



yields the same proportions of carbon and hydrogen a 

 fact worthy of notice when we consider that this fuel has 

 been derived from an assemblage of plants very distinct 

 specifically, and in part generically, from those which have 

 contributed to the formation of the ancient or palseozoic 

 coal." 



" It is true, however," says one of the most experienced 

 and practical of British geologists (Professor Ansted), 

 "that the great coal-fields of England, of Belgium, of 

 Spain, of France, and of North America, besides those of 

 Bohemia, Moravia, and the Rhine, of Russia and China, 

 and probably of Australia, belong to the oldest or palaeozoic 

 rocks, and that for some reason that may perhaps be better 

 understood at a future time than it now is, these deposits 

 are more regular, more uniform over large areas, and in 

 that sense more to be depended upon, than those of newer 

 date." * In other words, they belong to the Carboniferous 

 system, that great series of limestones, sandstones, shales, 

 ironstones, and coals, which has hitherto yielded the main 

 supplies of mineral fuel, and to which Britain owes so 

 much of her mechanical superiority and commercial great- 

 ness. As this system will form the subject of a separate 

 Sketch, we need only here observe that its coals occur in 

 many seams, of every thickness, from a few inches to forty 

 feet , of all degrees of purity, from earthy masses that 



* There can be no doubt that the difference here alluded to has arisen, 

 partly from the peculiar distribution of sea and land during the Carbon- 

 iferous era, which permitted over extensive areas a moist, genial, and 

 equable climate, and partly from the peculiar character of the vegetation 

 of the period, which seems to have been at once of rapid growth and of a 

 kind eminently fitted for preservation. Physical conditions like a moist, 

 genial, and equable climate may recur in the course of nature, but the 

 Life of each geological system is peculiar, and vanishes with the period 

 to which it belongs. The Carboniferous flora disappeared with its epoch ; 

 and no flora equally fitted for the formation of coal has since recurred or 

 may ever again recur in the progressional course of creation. 



