1818.] 



Transition Rocks of IVerner, 



415 



It is greatly to be wished that arrangements of this kind were 

 less dictated by theory. The pupils of the Wernerian school 

 have been peculiarly fettered by an ideal necessity of supporting 

 the principles of their master; but the blending of theory with 

 description is an error common to all speculative geologists, the 

 support of preconceived opinions being very generally the prin- 

 cipal object in view. Hence we find that collections of those 

 facts which are supposed favourable to certain doctrines have 

 been eagerly pursued^ and others, equally interesting in them- 

 selves, entirely overlooked ; while that minute detail, which is 

 alone capable of placing the student in a situation to draw con- 

 clusions of his own, has been totally neglected. 



The part of the Wernerian system which it is my intention to 

 notice at present, is the class of rocks termed transition. After 

 stating the grounds on which this distinction has been esta- 

 blished, and the particular rocks of which the series is composed, 

 with their extent and importance, I shall endeavour to show 

 that those which constitute its principal members are similar ia 

 different districts ; and, finally, that they are of an older date 

 than granite, which maintains the first place in point of priority 

 in the system of Werner. 



It is well known that one of the principal arguments brought 

 forward by Dr. Hutton is drawn from the penetration of the 

 stratified rocks by veins extending from the mass of granite, 

 which he considered as affording a decisive proof of the subse- 

 quent formation of that rock. It nTust not therefore be supposed 

 that I aim at any thing original in the above assertion, or that I 

 even wish to limit the term alpine schisius, as applied by that 

 ingenious philosopher; there can be no doubt that under this 

 name he included both the primitive and transition stratified 

 rocks of Werner ; but in his time no distinction had been drawn 

 between them : it is only later discoveries that have imposed the 

 necessity of more specific language, which may at once account 

 for that want of precision by which his writings are so much 

 obscured, and the deficiency of mineralogical knowledge with 

 which he has been so frequently charged. 



Werner, in the construction of his systematick arrangement, 

 thought that he perceived grounds for considering all rocks, 

 from granite down to clay-slate, as bearing marks of having 

 been desposited from the original chaotic fluid in a certain deter- 

 minate order. In them no detritus, or any thing like organised 

 nature, was to be observed ; and to this point every rock re- 

 mained exactly in the ^ame state, in which it was at the period 

 when it first acquired solidity. To these alone the title of pri- 

 mitive was attached. In the rocks immediately following, of 

 which limestone is said to be the first, he remarked an essential 

 difference; the limestone not only abounded in organic remains, 



