APHORISMS AND REFLECTIONS 71 



believe, it can be demonstrated that ordinary coal is 

 nothing but "saccular" coal which has undergone 

 a certain amount of that alteration which, if con- 

 tinued, would convert it into anthracite ; then, the 

 conclusion is obvious, that the great mass of the coal 

 we burn is the result of the accumulation of the 

 spores and spore-cases of plants, other parts of which 

 have furnished the carbonized stems and the mineral 

 charcoal, or have left their impressions on the surfaces 

 of the layer. 



CCIII 



The position of the beds which constitute the coal- 

 measures is infinitely diverse. Sometimes they are 

 tilted up vertically, sometimes they are horizontal, 

 sometimes curved into great basins ; sometimes they 

 come to the surface, sometimes they are covered up 

 by thousands of feet of rock. But, whatever their 

 present position, there is abundant and conclusive 

 evidence that every under-clay was once a surface 

 soil. Not only do carbonized root-fibres frequently 

 abound in these under-clays ; but the stools of trees, 

 the trunks of which are broken off and confounded 

 with the bed of coal, have been repeatedly found 

 passing into radiating roots, still embedded in the 

 under-clay. On many parts of the coast of England, 

 what are commonly known as " submarine forests " 

 are to be seen at low water. They consist, for the 

 most part, of short stools of oak, beech, and fir-trees, 

 still fixed by their long roots in the bed of blue clay in 

 which they originally grew. If one of these sub- 

 marine forest beds should be gradually depressed and 

 covered up by new deposits, it would present just 

 the same characters as an under-clay of the coal, if 

 the SigiHaria and Lepidodendron of the ancient world 

 were substituted for the oak, or the beech, of our 

 own times. 



In a tropical forest, at the present day, the trunks 



