106 Mr. Hawkins on the Nomenclature 



made of grey-wacke slate ; so little was he then disposed to 

 include in this new denomination, any thing which possessed 

 not the true derivative character. The same arrangement 

 subsisted at the period of my second visit to Freyberg in 1793; 

 but on my return thither in the year 1798, I found that some 

 very important changes had taken place in the order of the 

 Wernerian arrangements ; the class of transition rocks having 

 been introduced between the primitive and the secondary; at 

 the head of which new class, was placed that argillaceous slate, 

 which had been observed to contain organic remains; the 

 true grey-wacke being here stationed at the end of the series. 

 The primitive sort of argillaceous slate, on the other hand, still 

 kept its place in the system of arrangement, next to micaceous 

 slate. Admitting, as Werner did, that nature had repeated 

 the same operations at various intervals, there was nothing 

 in this separation of the argillaceous slate into two distinct 

 classes, which could be deemed unscientific. 



And here I could have wished, that the nomenclature, as 

 well as the arrangement of these rocks, had remained sta- 

 tionary, or at least subjected to such limitations as would have 

 obviated all that confiision which has since arisen. The chief 

 cause of this evil, I suspect to lie in our ignorance of the true 

 nature of grey-wacke. It has been generally considered as a 

 derivative rock, and this opinion is necessarily connected with 

 the notion of a previous disintegration of strata of ai'gillaceous 

 slate, and the removal or reunion of their fragments. But, if 

 this had been the case, nature mi questionably would have left 

 a bold line of distinction between strata, the origin of which 

 had been so essentially different ; whereas no such line exists, 

 the transition of one rock into the other being insensible, 

 Tliis shows that both owe their origin to the same mode of 

 deposition, tlie nature of which has been apparently both che- 

 mical and mechanical, without being derivative ; except in 

 those cases, where the fragments of one bed are found inclosed 

 in another. By our adoption of this hypothesis, we should 

 indeed exclude grey-wacke, as a distinct rock-fonnation, and 

 admit it only as a subordinate one, which may have some in- 

 conveniences, although none that I know of, that can be com* 

 pared with those .'.rising from its present station in the system ; 

 where it seems to be perpetually struggling not so much for 

 existence, as for exclusive dominion. 



As it appears, therefore, that the two rocks here mentioned 

 cannot be separated in any system of geology, without some 

 violence to nature ; would it not be advisable to include both 

 under the general denomination of the older ; distinguishing the 



primitive 



