484 ON THE SUCCESSIVE FORMS 



will probably extend this certainty. But till those upper 

 deposits of coal which I have here called Lignites, are 

 distinguished every where, we must not be hasty in 

 deciding on the extent of this particular revolution. 



But the extent of the revolution by which that 

 surface, at least, on which the coal strata were formed, 

 was depressed, rests far less on them than it does on the 

 next subsequent general formation, or on the red 

 marl. Wherever this occurs, the strata on which it 

 lies were beneath the ocean at the time of its forma- 

 tion, and probably at one period, though this cannot 

 be absolutely proved. Now it appears to be as ge- 

 neral a rock as any that is known; being assuredly 

 far more widely diffused than any other secondary 

 stratum, and, if the term universal is ever admissible, 

 peculiarly deserving of it. 



Hence therefore we may conclude, that not only 

 was the earth on which the coal strata were formed, 

 depressed beneath the ocean wherever these are found, 

 whether covered by the red marl or not, but probably 

 wherever that stratum occurs in any state of sequence 

 to the inferior rocks; unless indeed a similar rock 

 should have been forming beneath the ocean at the 

 same time as the coal ; and this being the peculiar 

 difficulty which we cannot yet solve. 



This revolution, which depressed the coal strata, 

 will, whatever its extent may be, appear an exception 

 to all others, in the eyes of geologists, who have over- 

 looked this plain inference, and who also have for 

 ever coupled the notion of elevation alone with that 

 of revolution. But I shall soon show that the same 

 effect has probably happened in every other revolution; 

 though the peculiarity of this deposit allows us to prove 

 in this case what we cannot do in the others, as it will 

 also be an argument of analogy respecting those. 



It must still be observed, that the depression of the 



