VEGETABLES. 191 



with branches and smaller vegetables filling up their interstices, 

 would form a coal seam; and a large accumulation of such materials 

 would constitute a bed of coal. We know not indeed, by what process 

 nature has converted wood into jet, or into coal; but we are equally 

 ignorant of the way in which wood has been transmuted into silex, 

 or a mass of shells into limestone. Since however, we are sure, that 

 the process has been conducted on a small scale, why not also on a 

 large? The same power that converted a single tree into jet, might 

 form an assemblage of such trees into a seam of cannel coal, or 

 Bovey coal : and the same process that reduced a detached block of 

 wood to the state of common coal, might produce, from accumula- 

 tions of such blocks, the largest beds of pit coal. The quantity of 

 the materials required is no obstacle in the way of this hypothesis ; 

 for if the stores of nature could furnish such prodigious quantities of 

 shellfish, to fill our oolite and other beds, her magazines of vegetable 

 matter, if in tlie same proportion, would more than suffice to replen- 

 ish all the coal pits hitherto discovered. 



Marine plants are not commonly found in a petrified state ; yet 

 the group represented in Plate IV, Fig. 9, may almost be affirmed to 

 be of that class. It is a specimen of long cylindrical bodies, found in 

 great quantities on this coast, bearing a striking resemblance to the 

 stalks of the common tangle, and often appearing in pairs, as these 

 stalks are wont to grow. Like these stalks, they have a brown 

 coating ; and the appearance of brown leaves among them, or of a 

 brown substance that may have been formed of the leaves, strength- 

 ens the analogy. The cross section of the petrifaction has also, in 

 some instances, a resemblance to that of the plant, displaying the 

 same concentric zones; but the petrified bodies are seen, in some 

 places, to run into one another, or to be connected by lateral: 

 communications, such as we do not know to exist in any species, 

 of the recent plant.. 



