REVIEWS. 851 



erland. This map, which was published on a scale of 1 : 100,000 in 

 1885, embraces the area between the St. Gotthard railway and the 

 Rhein, north of the great central (Tessin) massif which forms the 

 south flank of the Alps. Hence it includes the eastern portion of the 

 Aar and Gotthard massifs, with all the younger formations in their 

 most disturbed and implicated development. The thirteen years 

 which have elapsed since the appearance of the earlier work have so 

 greatly multiplied observations and stimulated thought that the stand- 

 point regarding the whole subject of dynamic metamorphism is seen 

 to be far advanced. Nor has Professor Heim himself been instrumental 

 in any small way in bringing about this result. Aside from his own 

 detailed field work, his suggestions as to the efficacy of orographic 

 movement as a metamorphosing agent have been of profound and 

 world-wide influence. Hence we cannot be surprised that he should 

 have inspired enthusiastic students within the limits of his own special 

 field. Others have worked out under his direction many details upon 

 which some of his own broadest and most far-reaching generalizations 

 rest. Some of the best of these results appear almost simultaneously 

 with his latest work and form an integral portion of it. This is nota- 

 bly true of the special petrographic studies of both the eruptive and 

 sedimentary rocks of two important and much discussed horizons — the 

 Biindnerschiefer and the Verrucano — in both of which the processes 

 of dynamometamorphism can be made out clearly and precisely fol- 

 lowed. 



More than one quarter of the Swiss atlas sheet XIV is occupied 

 by that diversified complex of phyllites and schists, called by Heim 

 the Biindnerschiefer . Their stratigraphical relations are, on account of 

 the dislocations to which they have been subjected, often very obscure. 

 They have been variously interpreted by different observers, but as the 

 result of years of mature observation Professor Heim gives a full pre- 

 sentation of the facts, and now concludes that he must differ with 

 Bonney, Giimbel, Diener and others who have ascribed to them a 

 greater age, and agree with A. Escher v. d. Linth, Theobold and 

 Rolle who regard them as a united and continuous series belonging in 

 fhe main to the Lias. Toward the east, where these schists have their 

 broadest and least disturbed development, they are comparatively little 

 altered, and consist of calcareous shales and phyllites, impure lime- 

 stones, sandstones, dolomitic and gypseous beds, interstratified with 

 green schists and serpentine which are shown by microscopical exam- 



