222 Geological Society : — Anniversary of 1839. 



an additional interest to geological researches; conducted on so 

 large a scale as those of Prof. Sedgwick. Mr. Marchison's mode 

 of investigation may be described thus: that he has applied, for 

 the first timCj to the rocks below the Old Red Sandstone^ the 

 method of classification previously employed with so much suc- 

 cess for the Oolites. It is truly remarkable, that Nature has 

 placed in this our corner of the world, series, probably the most 



complete which exist, of both these groups of strata; and as the 



Oolites of England have long been the type of that portion of 

 European geology, the Silurians of Wales may perhaps soon be 

 recognizedj as the standard members of a still more extensive 

 range of deposits- As if Nature wished to imitate our geological 

 maps, she has placed in the corner of Europe our island, contain- 

 ing an Index Scries of European formation in full detail 



The Carboniferous, Old Red, Silurian, and Cambrian systems 

 have, by many writers, up to the present time, been all compre- 

 hended in the term " transition rocks," so far as that term has 

 been used with any definite application at all. The analysis of this 

 vague group into these distinct portions removes the confusion 

 and perplexity which liave hitherto prevailed in this province of 

 geology. Prof. Sedgwick has further proposed to apply the term 

 Palaeozoic, and Mr. Murchison that of Protozoic. to the rocks 



which constitute the Cambrian and Silurian systems. 



How far these appellations are useful, we shall see when we 

 have had speculations presented to us in which they are familiarly 

 used ; for necessity is the best apology, and convenience the best 

 rule, of innovations in scientific language. In the names applied 

 to the members of the Silurian system, Mr. Murchison, following 

 those examples of geological nomenclature which have been most 

 clearly understood and most generally adopted, has borrowed his 

 terms from localities in which standard types of each stratum oc- 

 cur. If the Silurian system be as exclusively diff'used as some 

 indications seem to imply, we may find the Ludlow Rocks in 

 Scandinavia, and the Caradoc Sandstone even in Patagonia. 

 Whether a like identification of the more ancient rocks of the 

 Cambrian series with the lowest formations of other countries be 

 possible, may perhaps be (for the present) more doubtful. 



I have spoken of Mr. Murchison's \vork as if it had formed 



part 



appears 



And I will 



