NOTES TO BOOK XVIII. 681 



has been termed Trias by the continental geologists. The 

 Neocomien is so called from Neuchatel, where it is largely 

 developed. Below all these rocks come, in England, the 

 Cambrian, on which Prof. Sedgwick has expended so 

 many years of valuable labour. The comparison of the 

 Protozoic and Hypozoic rocks of different countries is 

 probably still incomplete. 



The geologists of North America have made great 

 progress in decyphering and describing the structure of 

 their own country ; and they have wisely gone, in a great 

 measure, upon the plan which I have commended at the 

 end of the third Chapter; they have compared the rocks 

 of their own country with each other, and given to the 

 different beds and formations names borrowed from their 

 own localities. This course will facilitate rather than 

 impede the reduction of their classification to its synonyms 

 and equivalents in the old world. 



Of course it is not to be expected nor desired that 

 books belonging to Descriptive Geology shall exclude the 

 other two branches of the subject. Geological Dynamics 

 and Physical Geology. On the contrary, among the most 

 valuable contributions to both these departments have 

 been speculations appended to descriptive works. And 

 this is naturally and rightly more and more the case as 

 the description embraces a wider field. The noble work 

 On the Geology of Russia and the Urals, by Sir Roderick 

 Murchison and his companions, is a great example of this, 

 as of other merits in a geological book. The author 

 introduces into his pages the various portions of geological 

 dynamics of which T shall have to speak in Note (KA) ; 

 and thus endeavours to make out the physical history of 

 the region, the boundaries of its raisrd sea bottoms, the 



