GENERAL LAWS IX GEOLOGY. 539 



instead of sudden and abrupt. Thus the coal measures in the south of 

 Enojand are above the mountain limestone : and the distinction of the 



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formations is of the most marked kind. But as we advance north- 

 ward into the coal-field of Yorkshire and Durham, the subjacent lime- 

 stone begins to be subdivided by thick masses of sandstone and 

 carbonaceous strata, and passes into a complex deposit, not distinguish- 

 able from the overlying coal measures ; and in this manner the transition 

 from the limestone to the coal is made by alternation. Thus, to use 

 another expression of M. de Humboldt's in ascending from the lime- 

 stone, the coal, before we quit the subjacent stratum, preludes to its 

 fuller exhibition in the superior beds. 



Again, as to another point : geologists have gone on up to the 

 present time endeavoring to discover general laws and facts, with 

 regard to the position of mountain and mineral masses upon the surface 

 of the earth. Thus M. Von Buch, in his physical description of the 

 Canaries, has given a masterly description of the lines of volcanic action 

 and volcanic products, all over the globe. And, more recently, M. 

 Elie de Beaumont has offered some generalizations of a still wider kind. 

 In this new doctrine, those mountain ranges, even in distant parts of 

 the world, which are of the same age, according to the classifications 



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already spoken of, are asserted to be parallel* to each other, while those 

 ranges which are of different ages lie in different directions. This 



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very wide and striking proposition may be considered as being at 

 present upon its trial among the geologists of Europe. 5 



Among the organic phenomena, also, which have been the subject 

 of geological study, general laws of a very wide and comprehensive 

 kind have been suggested, and in a greater or less degree confirmed 

 by adequate assemblages of facts. Thus M. Adolphe Brongniart has 

 not only, in his Fossil Flora, represented and skilfully restored a vast 

 number of the plants of the ancient world ; but he has also, in the 

 Prodromvs of the work, presented various important and striking 

 views of the general character of the vegetation of former periods, as 



1 We may observe that the notion of parallelism, when applied to lines drawn 

 on remote portions of a globular surface, requires to be interpreted in so arbitrary 

 a manner, that we can hardly imagine it to express a physical law. 



6 Mr. Lyell, in the sixth edition of his Principles, B. i. c. xii., has combated 

 the hypothesis of M. Elie de Beaumont, stated in the text. He has argued both 

 against the .catastrophic character of the elevation of mountain chains, and tha 

 parallelism of the contemporaneous ridges. It is evident that the former doc 

 trine may be true, though the latter be shown to be false. 



