536 HISTORY OF GEOLOGY. 



of the Mississippi, the west coast of North America, and the moun- 

 tains of South America. Again, the labors of Prof. Sedgwick and 

 Sir R. Murchison, in 1836, '7, and '8, aided by the sagacity of Mr. 

 Lonsdale, led to their placing certain rocks of Devon and Cornwall as 

 a formation intermediate between the Silurian and Carboniferous Se- 

 ries ; and the Devonian System thus established has been accepted by 

 geologists in general, and has been traced, not only in various parts of 

 Europe, but in Australia and Tasmania, and in the neighborhood of 

 the Alleganies. 



Above the Carboniferous Series, Sir R. Murchison and his fellow 

 laborers, M. de Verneuil and Count Keyserling, have found in Russia, 

 a well-developed series of rocks occupying the ancient kingdom of 

 Permia, which they have hence called the Permian formation ; and 

 this term also has found general acceptance. The next group, the 

 Keuper, Muschelkalk, and Bunter Sandstein of Germany, 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 labor. 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 decy- 

 phering 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 ena of the third Chapter ; they have compared 

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

 ferent 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 I 

 shall have to speak afterwards ; and thus endeavors to make out the 



