Reviews — Short Notices, chiefly Mineralogical. 81 



been ably handled by Mr. S, S. Buckman, and a summary of bis 

 views is given in one of the chapters, illustrated by a good physical 

 map and by an effective view of meanders of the Eiver Coin. 



The volume is illustrated also by six photographic plates of 

 fossils, mostly from the writer's collection, and among these only 

 two ammonites are pictured : Paltopleuroceras pseudocostatum 

 belonging to the " spinati hemera," and Liparoceras capricornu to 

 the " capricornus hemera." 



We may repeat, in conclusion, that to the seriously minded 

 worker on the Cotteswold Hills this handbook will be a real help 

 in indicating the present knowledge of the zonal palaeontology of the 

 district. Details of a great many pit-sections are given, accompanied 

 by some capital photographic illustrations and sundry diagrams ; 

 there are illustrations also of the Girvanella and its connection with 

 the little concretionary nodules of the Pea-Grit. The Appendices 

 comprise a short list of minerals, copious lists of fossils, and an 

 explanation of the geological map, reproduced from that of the 

 Geological Survey, to which the author has made some additions. 



H. B. W. 



IV. — Ore Deposits : a Discussion. pp. 90. (New York : 

 Engineering and Mining Journal, 1903. Price 5s. net.) 



EAELY in 1903 two meetings of the Geological Society of 

 Washington were devoted to a discussion on the genetic 

 classification of ore deposits, in which several well-known geologists 

 (S. F. Emmons, W. H. Weed, J. E. Spurr, W. Lindgren, J. F. Kemp, 

 F. L. Eansome, T. A. Eickard, and C. E. Van Hise), who have done 

 special work on ore deposits in connection with the United States 

 Geological Survey, took part. The discussion was fully reported in 

 the pages of the Engineering and Mining Journal, and, together 

 with an introductory review, it is now reprinted in book form. An 

 article by C. W. Purington entitled " Observations on Gold Deposits " 

 is also reprinted as an appendix from the same journal. 



A tentative classification, on which the discussion was based, was 

 proposed by W. H. Weed, an outline of which is given below. 

 Other classifications are proposed by Spurr and Van Hise. Although 

 there are still considerable diversities of opinion, it is interesting to 

 note that the theory of ' lateral secretion ' finds little or no favour. 

 For nearly all deposits of any importance an igneous origin, either 

 directly or indirectly, is ascribed. 



Genetic Classification of Ore Deposits. 



I. Igneous (magmatic segregations). 



A. Siliceous (aplite and quartz- veins). 



B. Basic. 



II. Igneous emanations. Deposits formed by gases above or near 



their critical point. 



A. Contact-metamorphic deposits. 



B. Veins (closely allied to magmatic veins and to division IV). 



DECADE V. — VOL. II. — NG. II. 6 



