552 Scientific Intelligence. 



island chains. This peculiarity of distribution is strongly con- 

 firmatory of the theory that the troughs represent modern and 

 probably continuing deformation of the ocean bed. w. m. d. 



9. Volcanoes, their Structure and Significance; by T. G. 

 Bonney. Third edition. Pp. 379 ; 21 figs., 16 plates. New 

 York, 1912 (G. P. Putnam's Sons). — The popularity and useful- 

 ness of this volume is shown by its passage into a third edition. 

 Here are brought together into clear and interesting form the 

 descriptions of volcanoes and their great eruptions which man 

 has witnessed, including those important outbreaks which have 

 occurred since the first edition of the work was published. The 

 numerous high-grade illustrations add much to the volume. The 

 titles of the six chapters indicate the range of the contents and 

 are as follows : The life history of volcanoes ; the products of 

 volcanoes ; the dissection of volcanoes ; the geological history of 

 British volcanoes ; the distribution of volcanoes ; the theories of 

 volcanoes. j. b. 



10. JEJssai sur la genese et revolution des roches ; par Alfred 

 Vialay, ingenieur. 8°, pp. x, 226. Paris, 1912 (H. Dunod et E. 

 Pinat). — This work by a French engineer furnishes an interest- 

 ing instance of reversion in geological theory, quite as remark- 

 able as some in the organic world. The author has been impressed 

 by the great variety and range in chemical composition exhibited 

 by igneous rocks and has attempted an explanation of this 

 diversity which is quite unlike magmatic differentiation, assimi- 

 lation, or other current hypotheses. He has approached the 

 problem from the standpoint of the chemist, with little or no 

 regard for the facts of occurrence or the inner characters of the 

 rocks themselves, as established by microscopical research. 



M. Yialay revives the Wernerian hypothesis that most igneous 

 and metamorphic rocks are in fact of aqueous origin. They are 

 conceived as derived by metasomatic processes from basalt or 

 diabase ; these being regarded as in fact nothing bat altered 

 greensand and allied marine deposits included under the French 

 term glauconie. The potent agency invoked to accomplish this 

 metasomatic change or diagenesis is carbonated water at a tem- 

 perature not exceeding 150° or 200° C. Voluminous citations 

 from Bischof, Mohr, Sterry Hunt, Roth and others are given to 

 show the character and great extent of the changes effected by 

 circulating waters. Rocks more siliceous and alkalic than diabase 

 and basalt are products of the leaching action of carbonated 

 water, which removes magnesia, lime, iron and soda more readily 

 than alumina and potash. Thus diabase passes into diorite, 

 syenite and granite, while basalt yields andesite, dacite, phonolite, 

 trachyte and liparite. More complex processes have produced 

 other extreme variants from the sedimentary rock. 



Dikes are considered as simply the filling of fissures by deposi- 

 tion from solution. Basalt is not a volcanic rock, in the view of 

 M. Vialay, at least not in the great basalt fields of the world. 

 The proof of this lies in the frequently observed interstratifica- 



