416 



Remarks on the 



but other members of the series were composed of fragments, 

 which must have existed previously in a different state : hence 

 he inferred that these rocks were formed at a subsequent period, 

 which, from their constituent parts, he concluded must have 

 been after the creation of living animals, and nearly at the time 

 when the earth passed from its chaotic to its habitable state;* 

 and on these grounds he distinguished this class by the name of 

 transition. 



To this another class succeeded, also presenting new and dis- 

 tinct characters, one of the most remarkable of which is position. 

 They are never found conformable with the transition rocks ; 

 while these present an uneven or serrated outline, either from 

 the natural contortions of the strata, or the broken edges of the 

 highly inclined beds ; the rocks which succeed fill up the in- 

 equalities, and assume an horizontal position. To them he gave 

 the name of floetz rocks. 



Thus the system is divided into three great clases, the primi- 

 tive, transition, and floetz. 



Although the transition has been known in this country as a 

 separate class only within a few years, yet it occupies a larger 

 superficial extent in these islands than any other rock formation. 

 But before I proceed to trace its limits, it may he proper to 

 explain what is understood by the transition series. In doing 

 this, and indeed in whatever else I have stated with respect to 

 the Wernerian geognosy, I beg to be understood as having taken 

 it from that work, Vv^hich I consider as containmg the most 

 authentic account of the system taught at Freyberg : I mean the 

 third volume of Professor Jameson's Mineralogy. As Werner 

 has published no account of it himself, it is only from the works 

 of his pupils that we can become acquainted with his system. 

 After the intense labour which has been bestov/ed on bringing it 

 for ward, t it cannot be supposed to contain any errors, accord- 

 ing to the strict notions of Werner; and if his pupils find it 

 necessary to introduce any material alterations, and so to mould 

 it, as to suit their own subsequent observation?, it will no longer 

 be the system of that philosopher, — which the arguments in the 

 present paper are alone intended to meet. 



The transition series is composed of limestone, graywacke, 

 and graywacke-slate, trap and flinty-slate. Limestone is placed 

 first, as being the oldest member, and is said to rest immediately 

 on the newer clay-slaie. J Of this we have no instance which I 

 am acquainted with in Scotland, where, indeed, transition lime- 



* Jameson's Mineralog}', vol. iii. p, 140. 



f Werner, " after the most arduous and long-continued investigation, con- 

 ducted with ihe most consummate address, discovered tiie general structure 

 the cruEf of the g-iobe," oic. Jameson's Miueralogyj vol. iii, p. 42, 



X Jameson's Mineralogy^ voL iii. p. HT. 



