ON THE ORIGIN OF COAL-FIELDS. 



149 



This view, however, of the former probable condition of the surface of this part of 

 our island, during the accumulation of the carbonaceous deposits, though quite intelli- 

 gible to geologists, may with difficulty be apprehended by persons unaccustomed to 

 estimate the weight of the evidences on which it is based. For such of my readers 

 therefore I here offer a slight sketch of some of the proofs from which the inferences 

 have been deduced. 



The discoveries of modern geographers have shown to what great distances vegetable 

 materials, drifted by streams from the land on which they have grown, are de- 

 posited amid silt and sand. The narratives of Franklin and Back, but more parti- 

 cularly that of Richardson, in describing the polar regions, inform us that the rivers 

 are there constantly transporting wood and plants, sometimes heaping them up in the 

 large freshwater lakes and embayed sea openings, which occupy large portions of 

 that continent ; at other times sweeping them out to the open sea, and lodging them 

 upon its shores. In the central territories of the same vast continent, we have the 

 testimony of Capt. Basil Hall, that similar accumulations are constantly taking place 

 towards the mouth of the Mississippi ; and hence we have every reason to conclude, 

 that all great rivers descending from wooded countries must be daily forming like de- 

 posits. 



Such existing causes (ample illustrations of which will be found in LyelPs Principles 

 of Geology,) serve therefore as the first link in the chain of evidences ; for they explain 

 to us how the vegetables from which coal has been formed, may have been carried into 

 their present positions from adjacent lands. 



The chemist proves, that the ultimate elements of coal are identical with those con- 

 tained in plants ; and that it is in entire accordance with the laws and known pheno- 

 mena of chemistry, that a new compound such as coal may result from gradual changes 

 among the elements of vegetables. The observations of Hatchett indeed distinctly 

 lead to the opinion, that it is especially the resinous principles of plants which have 

 mainly contributed to the production of coal 1 . 



Armed therefore with these data, the geologist proceeds to examine the natural phee- 

 nomena laid open in the various deposits constituting the crust of the globe. Even in 

 the most superficial of these, he finds occasionally some vegetable matter which has 

 partially lost its original properties ; in other strata of nearly the same age, these ma- 

 terials appear in that peculiar state of carbonization termed " brown coal"; whilst even 

 in beds younger than our London clay, he perceives that all the vegetable tissue has 

 disappeared, the mass having been transmuted into the black solid and shining mineral 

 we call coal. 



With such phenomena before our eyes, it is no wild hypothesis to suppose, that if 

 the transatlantic region alluded to were drained, or, in other words, if the bottoms of the 



1 See also MacCulloch's ingenious observations on the formation of coal out of vegetables. (Geol. Trans., Old 

 Series, vol. ii. p. 1.) 



