Rocks of North Devon ^ Sfc. 119 



And if such be the case, the same may be predicated of the 

 Older Stratified Rocks of South Devon and Cornwall also, 

 since similar relations are stated to exist in those districts as in 

 North Devon. And this conclusion will bring us back to the 

 position formerly entertained, and I believe correctly; namely, 

 that a large portion of the Older Stratified Rocks of South 

 Devon and Cornwall belong to the transition system *. But 

 to what portion of that system? it may be asked. The ques- 

 tion implies the impression of a determinate order of succes- 

 sion in the transition series. Does such a sequence strictly 

 prevail in nature, so as to admit of general application? I 

 do not conceive that an affirmative reply would be correct, if 

 we may judge by what we have hitherto learnt from the de- 

 scription of our own and other countries. And in avowing this 

 persuasion, far be it from me to disparage in the slightest de- 

 gree the assiduous and invaluable labours of Prof. Sedgwick 

 and Mr. Murchison. The Silurian system of the latter can- 

 not be too highly appreciated, as no doubt will also be the case 

 with the Cambrian system of the former, whenever the public 

 shall be gratified by the appearance of that work in all its de- 

 tails. As comprising an able development of the structure 

 and composition of the districts described, together with the 

 fossils by which they are characterized, as well as of the dis- 

 turbing forces by which they have been affected, the Silurian 

 system will always maintain a high rank in geology. Yet, if 

 we duly consider the tumultuary throes under which the ar- 

 rangements of the transition epoch appear in general to have 

 taken place, and the consequent uncertain and fluctuating dis- 

 position of the mineral masses composing the system, with a 

 distribution of organic remains much depending on the me- 



carboniferous series. Bat Mr. Murchison would now restrict the carboni- 

 ferous system to the carboniferous limestone and coal-measures merely. 

 In so doing, I think, he departs from nature. Time will prove which of 

 the preceding views may be the more correct one. 



* To designate these rocks as the representative or equivalent of the Old 

 Red Sandstone formation strikes me as singularly inappropriate ; that is, 

 if we continue to retain any respect for mineralogical distinctions, and 

 are not carried away by hypothetical views. A practical man does not so 

 readily conceive that a glossy clayslate, for example, in association with 

 a variety of other rocks, and such series containing numerous fossils, can 

 be the equivalent of the Old Red Sandstone formation, properly so called, 

 wholly destitute of these fossils. 



I mean to say that mineral characters are always entitled to a fair share 

 of our consideration, in combination with organic remains and relative posi- 

 tion, when judging of the relative age of rocks j and that to exclude from 

 our view either one or the other of these marks of distinction, is to run 

 the risk of falling into error, and confounding subjects really distinct. 



