852 THE JOURNAL OF GEOLOGY. 



ination to be altered volcanic material in conformable layers. Farther 

 west, where these same rocks become tightly compressed between the 

 gneisses of the central massifs, they have become recrystallized in pro- 

 portion to the amount of their dislocation. " The study of the Bund- 

 nerschiefer," says Heim, "was that which years ago first convinced me 

 of the possibility and reality of crystalline metamorphism being pro- 

 duced without the agency of eruptive contact, since I here for the 

 first time observed how a belemnitiferous calcareous argillite became 

 gradually more and more crystalline by the development of such 

 minerals as mica, garnet, hornblende, zoisite, etc., at first as indistinct 

 and imperfect nodules, and later as good crystals" (1. c, p. 52). The 

 Biindnerschiefer, both in their less altered localities and in occasional 

 beds, which have been by chance saved from metamorphism, are quite 

 rich in Jurassic fossils. 



About one-half of Professor C. Schmidt's appendix to Professor 

 Heim's monograph is devoted to the petrographical description of the 

 Biindnerschiefer, while the remainder treats of the crystalline rocks of 

 the Aar, Gotthard and Adula massifs. A few preliminary remarks on 

 the melaphyre of the Karpfstock supplement the author's earlier com- 

 munications with reference to the eruptives occurring in the Glarner 

 double-fold. 1 The rocks from the three crystalline massifs are mainly, 

 the characteristic Alpine gneiss-granites or protogine, with dioritic or 

 amphibolitic interpositions. Sericite- ottrelite- paragonite- zoisite- 

 glaucophane-schists and eclogites also occur. The Adula gneiss is 

 characterized by a green potash-mica (phengite) which is both uniaxial 

 and biaxial. The rocks of the Biindnerschiefer are described by 

 Schmidt under two principal heads : a) gray and black schists which 

 are more or less completely metamorphosed sediments ; and b), green 

 schists which are foliated and metamorphosed eruptive material. 

 Under the first division are mentioned schists with newly crystal- 

 lized chloritoid, zoisite, tourmaline, epidote, biotite, muscovite, quartz, 

 plagioclase and rutile. In some cases complete pseudomorphs of 

 zoisite after echinoid remains are to be found. Other more tightly 

 compressed beds at Nufenen, Val Piora, Lukmanier, Scopi, Ariolo, 

 and other localities are still more highly crystalline, containing dis- 

 thene, garnet, staurolite and similar minerals in abundance. These 

 rocks have also been petrographically studied by Prof. U. Grubenmann. 2 



1 Neues Jahrbuch fur Min., etc., Beil. Bd. IV., p. 28S, 1886. lb., 1887, 1., p. 58. 



2 Mitth. Thurgauischen Naturf. Gesellsch., Heft. VIII., 1888. 



