REVIEWS 525 



first volume are not to be found in the full index. There seems also to have been 

 differences in the methods of compiling the indexes to the two volumes. The 

 detail of the index to the second volume is less full than in Volume I., as may 

 be seen by comparing the references to, say, Australia or Canada, in the two 

 volumes. The bibliographies are occasionally incomplete. To take a single 

 example, that of the West Australian "young" gold-silver lodes only includes 

 memoirs up to 1903. In some cases, however, references appear to have been 

 added from 1909, the date of publication of the original German work. 



Coming now to the matter of the second volume, one of the most valuable 

 characters of the work, as we noticed in the first volume, is the comprehensive 

 description of the, to English-speaking investigators, little-known but important 

 European ore-occurrences, many of which are illustrated by excellent geological 

 maps. The first volume ended at an early stage in "Lodes and Metasomatic 

 Deposits," having completed the description of the tin, apatite, and quicksilver 

 lodes. The second volume thus begins with the "young" gold-silver lodes, and 

 goes on to describe the " old " gold lodes, and other important groups. These are 

 followed by the ore-beds, which include many famous iron-ore fields, the auriferous 

 conglomerates, and the tin, gold, and platinum gravels. Interspersed in the 

 purely descriptive material are sections devoted to a closer discussion of theoretical 

 points than was attempted in the first part of the work. Instructive comparisons 

 may be drawn between this work and the latest American work on the same 

 subject— Lindgren's Mineral Deposits. Beyschlag, Krusch, and Vogt classify ores 

 as magmatic segregations, contact deposits, cavity-fillings and metasomatic de- 

 posits, and ore-beds, in an order of decreasing relation to the eruptive rocks from 

 which their materials have been ultimately derived. Lindgren's classification is 

 into two groups only— deposits formed by mechanical and chemical modes of con- 

 centration respectively. The latter group is elaborately subdivided with an 

 attempt to delimitate conditions of temperature and pressure for the various 

 classes. Curiously enough Lindgren's classification, made from a totally different 

 standpoint, works out in practically the same order with regard to eruptive origin 

 as that of the work under review. 



We have not sufficient space to criticise the work in as much detail as it 

 deserves, but we may notice one or two points. A distinction is made between 

 the "young" gold-silver and the "old" gold lodes, which is reminiscent of a still 

 active principle in German petrological thought. The former group corresponds 

 generally with Lindgren's class of deposits formed in connection with igneous 

 activity, but at slight depth and at low temperature and pressure. The " old " 

 gold lodes are regarded by this author as formed in the same way, but at greater 

 depth and higher temperature and pressure. Beyschlag, Krusch, and Vogt, 

 however, regard the West Australian gold-telluride ores as belonging to their 

 "young" group, whereas Lindgren places them among the high-temperature lode 

 deposits. It is notable, also, that the authors decide for an infiltration theory as 

 against the marine placer theory advocated by J. W. Gregory and others for the 

 origin of the auriferous conglomerates of the Witwatersrand. The recent work of 

 the Transvaal Geological Survey, however, has produced evidence strongly in 

 favour of the latter mode of origin. The present volume brings this book to a 

 premature ending. The third volume indicated by its title has, so far as is 

 known, not yet appeared ; but it is not perhaps too much to hope, that when the 

 present cataclysm has passed, the worthy conclusion to at least one great work 

 " made in Germany " will appear. 



G. W. T. 



