Reviews. 



SOME RECENT ALPINE STUDIES. 



Beitrdge zur Lelire von dcr Regionalmctamorphosc. L. Milch 

 (Neues Jahrbuch fur Mineralogie u.s.w., Beilage Band IX., 

 1894). 

 Ztir Classification der unorganogenen Gesteine. L. Milch (same 



journal). 

 Etudes dans les Alpes Francoises. Marcel Bertrand (Paris, 

 1894). 



Through the classic works of Heim and Lehman in 1878 and 1884, 

 the problems of metamorphism were clearly set forth and attention 

 was called to the fact that nowhere in the world were the conditions 

 more favorable for their solution than in the Alps. In this region all 

 gradations were to be found from the least metamorphosed sediments 

 to the most highly altered elastics and eruptives. Investigators of 

 marked ability were attracted to the field and a very copious literature 

 on Alpine metamorphism has resulted. Their success led to similar 

 work in numerous other fields where these same problems had been 

 considered as incapable of solution. These workers look with interest 

 to all contributions to the knowledge of Alpine geology, for they are 

 sure to contain valuable suggestions for the prosecution of work on the 

 crystalline schists the world over. 



During the past few months Dr. Milch of Breslau has published a 

 second paper on the dynamic phenomena of the Verrucano. In a 

 former paper 1 he discussed the subject of the dynamic metamorphism 

 of the eruptive rocks, and in the present paper he gives some results of 

 a study of the metamorphism of the sediments as bearing on the 

 general subject of regional metamorphism. 



Many of these altered sediments show typical clastic grains, while 

 others have lost all trace of such character. Such rocks are divided 

 according to the nature of the alteration into the following groups : 



1 Reviewed in Journal of Geology, Vol. I., No. 8, p. 850. 



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