126 Dr Boue on the Elevation of Mountain Chains, 



number of groups according to tlieir directions. This is a 

 longer definition than that of M. de Beaumont, and it is even not 

 so well Hmited, but I think it is more conformable to the phe- 

 nomena presented in nature, which, indeed, are of such a descrip- 

 tion as to baffle very strict classification. 



On the other hand, M. de Beaumont contends, that " le 

 nombre des dislocations n'est jamais tres grand, qu'il est a peu 

 pres du meme ordre que celui des changements de nature et de 

 gisement que presentent les depots de sediment de chaque 

 contree, changements qui les ont fait distinguer depuis Fuchsel 

 (J. de Geolog. v. ii. p. 190) et Werner, en un certain nombre de 

 formations, et qui ont ete consideres comme etant chacune le 

 resultat d'un grand phenomene physique," (p. 621.) I agree 

 with Mr Lyell (Princ. vol. iii. p. 341,) that we should come 

 to some agreement as to the meaning of the words formation 

 and dislocation. If the first term were extended so far as that 

 we should consider as formations the gypsum of Montmartre and 

 the coarse marine limestone of Paris, we should not be able to 

 understand one another ; but yet I suppose M. de Beaumont 

 is of this opinion. 



In regard to the word dislocation, it is synonymous with se- 

 paration and disjointing; and, taking this general designation, 

 it appears to me that the dislocations of the ground are not 

 nearly numerous enough to correspond with the directions of 

 the chains. But I enter into the abstractive idea of M. de 

 Beaumont, who, in this way, has only indicated those great phe- 

 nomena which have raised up ranges of hills, while he has 

 omitted the minor changes which have taken place. I believe 

 that, in the present state of our knowledge, the twelve revolu- 

 tions, or systems of elevation, are too few even for Europe, 

 small as it is, in proportion to the whole surface of the globe. 



M. de Beaumont acknowledges that the number of systems of 

 elevation is by no means fixed for ever, (p. 123) ; and especially 

 in so far as the older formations are concerned. Indeed if we 

 include the whole surface of the globe, there seems to be nothing 

 against there being double or three times the number. Yet 

 there must be a limit to the greatest upraisings which have agi- 

 tated the crust of the earth, and M. de Beaumont has expressed 

 himself well on this subject (p. 661) : it is only in regard to the 



