Notices of Memoirs — Prof. Stefani — The Apian Alps. 373 



the famous statuary marbles of Carrara, and their true geological 

 horizon, now no longer doubtful, was first determined by Prof. 

 Stefani. Some of the limestones are in part siliceous, and there are 

 also beds of red jasper, several metres iu thickness, which are 

 regarded by the author as due to Radiolaria. 



In places the limestones are mainly composed of Crinoidal remains, 

 referred mostly to a single species, JEncrinus granulosus, Miinst. 

 Following the Trias in upward succession are limestones of Rhsetic 

 or Tnfraliassic age; the Lower Trias, including the zones of Psilonoti, 

 Angulati and Arietites ; the Middle and Upper Lias ; Jurassic schists 

 with Posidonoinya ornati, Quenst., which may probably represent 

 the Oxford Clay ; the Tithonian ; Neocomian ; Middle and Upper 

 Chalk ; Nummulitic limestones, clays and sands of Eocene age, 

 represented also by serpentines, gabbros and diabases ; gravels and 

 clays of Upper Miocene age ; Pliocene ; Post-pliocene and Glacial 

 deposits. References are given to the principal fossils present iu 

 these beds respectively, and they are briefly compared with syn- 

 chronous deposits in other parts of Italy and elsewhere in Europe. 

 The breaks or interruptions in this series are considered in a separate 

 chapter, and this is followed by a table showing in a concise form 

 the different successive zones and their characters. 



No small part of the work is taken up by a detailed description of 

 the various anticlinal and synclinal folds which form such marked 

 features of the Apuan Alps, and the characters and course of these 

 are well shown in the accompanying map and plates of sections. 

 The author treats further of the displacements of beds which have 

 been produced by foldings of the strata, and arrives at the conclusion 

 that the greater part of these displacements does not result from an 

 original discordance, but has been produced by movements in the 

 beds themselves. He likewise opposes the view that the formation 

 of the marbles and the uralitization of the Eocene diabases have been 

 due to phenomena of compression, and attributes these alterations 

 in the rocks to slow molecular changes produced or favoured by 

 circulating waters and by the ordinary metamorphic surroundings. 

 Jointings in the rocks, and the origin of valleys independently of 

 faults, are likewise considered. Numerous instances are given of 

 the partial inversion of strata which occur on the outer borders of 

 mountain chains, which result from purely superficial phenomena, 

 but may have nevertheless an important influence on the formation 

 of these ranges. 



The final chapter treats of the general conclusions on the origin of 

 mountains, deduced from the Apuan Alps, but having a wider 

 application. As the result of his observations, the author states that 

 the secondary folds which constitute mountains are probably only 

 the result of relatively subordinate phenomena which take effect at 

 no great distance below the terrestrial surface, in the interior of 

 greater and more general undulations, through compression produced 

 by the overlying superficial strata ; and in support of this view he 

 refers to the paper of Mr. Charles Davison ' 'On the Secular Straining 

 of the Earth.' 



1 Geol. Mag. May, 1889, p. 220. 



