35 8 HISTORY OP GEOLOGY AND PALEONTOLOGY. 



dynamic action which had been already afforded by experi- 

 mental attempts. 



In 1887, a few months after Lossen's work on the Taunus 

 had appeared, C. W. von Giimbel published his Geognostic 

 Description of the Eastern Bavarian frontier Mountains. 

 In it he tried to demonstrate that gneiss and crystalline 

 schist represented the oldest sediment which had separated 

 out under peculiar conditions from a magma impregnated 

 with superheated water. Giimbel regarded the cleavage of 

 gneiss and the crystalline schists in the Bavarian forest not 

 as a subsequent development, but as true stratification, and 

 compared the succession of the gneiss and schist series, as 

 well as the gradual transitions and frequent alternations of 

 the different varieties, with the characteristic appearances 

 observed in a series of sedimentary deposits. He described 

 the occurrence of certain massive rocks, such as granite, 

 syenite, diorite, sometimes in regular alternation with the 

 gneiss and schist, sometimes as intrusive bosses and dykes. 

 Judging from the resemblance in the mineralogical composi- 

 tion of all these massive rocks, Giimbel argued that the rock- 

 material must in all cases have had a similar origin, and 

 concluded that there was an underground magma constituted 

 like the primitive earth, and from which either sedimentary 

 schist and gneiss, or granitic bosses and layers, could develop. 



Justus Roth, who was one of the founders of the German 

 Geological Society, was an ardent supporter of the view that 

 all gneissose and schistose rocks represented the products of 

 the first consolidation of the crust. In his work on General 

 and Chemical Geology ', published in 1890, two years before 

 his death, Roth gave an unfavourable criticism of all theories 

 which advocated subsequent rock-deformation and meta- 

 morphism. He contended that the compact structure of 

 gneisses and schists, the absence of any amorphous or glassy 

 ground-mass, together with the mineralogical composition, are 

 features which indicate a plutonic, aquo-igneous origin. Their 

 bent and cleaved character was attributed by him to the 

 contraction of the earth and the consequent strains acting 

 during the formation of the series. 



Many geologists were, however, finding in the field ample 

 confirmation of Lossen's explanation of the mechanical defor- 

 mation of rocks. The well-known writings of Heim and 

 Baltzer on the Swiss Alps, of Renard on the rocks of the 



