Metamorphic Rocks. 127 



westward of the Alleghanies, is highly bituminous, as it ap- 

 proaches the igneous rocks to the east, gradually loses its bi- 

 tuminous and gaseous contents, and is finally converted into 

 anthracite. 



The concluding part of the first volume of the second series 

 of the " Bulletin de la Society Geologique de France," pub- 

 lished last year, contains an interesting, and, in many respects, 

 highly instructive account of the proceedings of the Society, 

 at their meeting at Chambery, in August 1844. During the 

 sixteen days it continued, several valuable papers were read, 

 and interesting discussions thereon are reported. Among 

 others, the subject of metamorphism was frequently brought 

 forward, and it appears to be the settled opinion of the most 

 eminent French, Swiss, and Italian geologists, who have 

 thoroughly examined the Alpine regions, that a great pro- 

 portion of the mica-schists, talc-schists, and clay-slates of the 

 Alps, long held as types of primitive rocks, are unquestion- 

 ably deposits of secondary age, metamorphosed by igneous ac- 

 tion. The neighbourhood of the place of meeting is described 

 by the Archbishop of Chambery, — who took an active part in 

 the proceedings, and who, from the communications he read, 

 seems to be a zealous geologist, — as one of the countries of 

 Europe the most interesting in this respect, and one in which 

 the modifications of metamorphic action may be traced from 

 its commencement to its extreme intensity with the greatest 

 facility. At the conclusion of the meeting, M. Virlet read a 

 paper on the participation which veins have had in metamor- 

 phic action, and brought forward some new views on the theory 

 of metamorphism. He states that it has generally been held 

 to be the result only of the action of plutonic rocks on the 

 sedimentary deposits with which they come in contact, but 

 that it is a far more complex operation, and is probably the re- 

 sult of several causes acting either simultaneously, separately 

 or successively ; among these he is disposed to ascribe much 

 to the addition of new materials, insinuating themselves in 

 the shape of gaseous emanations from the interior of the earth. 

 He also dwells much on the matter injected into fissures, 

 forming veins, as having had great effect, maintaining that in 

 all metalliferous regions, the greater the number of veins by 



