THEORY OF THE EARTH. 445 



geologists have forced into a correspondance with our 

 own, as sufficiently analogous to let this branch of the 

 theory stand, to the extent that I have assumed. 



But I must note this. The secondary strata have 

 heen divided into groups, termed " formations." This 

 is as much hypothesis as the forced correspondence of 

 remote deposits of strata: while these arrangements, 

 which have often also heen changed, are so purely fan- 

 ciful and capricious, that I cannot conjecture, even 

 what the assumed ground is ; what the reference to the 

 act of formation or production ; if indeed there has 

 ever been one. Nor can I see any ground for such 

 groupings, hut those which I shall here state : although., 

 whether the following principles be admitted or not, 

 there cannot possibly be a natural group of any rocks, 

 including, within two portions of these, either of the 

 great lignite deposits ; since these are the very evidences 

 of a terminated marine stratification. Nor can the 

 received groups be natural, or just ones ; from what I 

 have proved respecting the deposition of submarine 

 strata while the coal and the lignites were forming on 

 the surface. They have included, as following in ver- 

 tical order, strata which were, most assuredly, not thus 

 formed, and which therefore, however now inferred to 

 be, inferior ones, never can, in all places, be found in 

 a state of actual inferiority. In no sense then, can such 

 a group be a " formation," if that term is to possess 

 any meaning at all; since the strata associated in them 

 were once, in every sense, independent. And if it be 

 a word to serve some artificial purpose, that is an evil 

 one; because it becomes an hypothesis which is a de- 

 monstrated falshood, and therefore impedes the acqui- 

 sition of real knowledge. 



If such have been the arrangements, I do not pretend 

 to substitute a better method of grouping the upper 



