Reports & Proceedings — Geological Society of London. 137 



Northern Cordillera undertaken in co-operation with the United 

 States, and found that the formations are dominantly of sedimentary 

 origin, and range from Recent to probably pre-Cambrian age. 



4. The Ore Deposits of North - Eastern Washington. By 

 Howland Bancroft, including a section on The Republic Mining 

 District by Waldemar Lindgren and Howland Bancroft. United 

 States Geological Survey, Bulletin 550. pp. 215, with 26 figures 

 and 19 plates. Washington, 1914. 



The district described by the author comprises mainly the whole of 

 Stevens and Ferry Counties. The geology could not be determined 

 with certainty owing to the absence of fossils, but the rocks may be 

 referred to the Proterozoic, Palseozoic, Mesozoic, and Cenozoic eras. 

 One of the most conspicuous rocks is an intrusive granite. The 

 mineral resources are very varied, and include gold, silver, lead-zinc, 

 copper, iron, tungsten, nickel, antimony, and molybdenite deposits, 

 and also minerals used as fluxes. The various mines are described in 

 detail, and reference to the memoir is facilitated by an ■ excellent 

 index. 



5. Electric Activity in Ore Deposits. By Roger C. Wells. 

 United States Geological Survey, Bulletin 548. pp. 78. 

 Washington, 1914. 



As the result of considerable investigation in the laboratory the 

 author concludes that electric action may have played no small part in 

 the deposition of ores. Many metalliferous minerals can conduct 

 electricity and act as electrodes and as conductors of electric currents 

 in ore deposits. The chemical difference producing the greatest effect 

 appears to be that existing between oxidizing and reducing solutions. 

 Pyrites is so inert to many solutions as to function electrically like 

 unattackable electrodes for long periods, thus making oxidizing or 

 reducing solutions available for producing electric currents in ore 

 deposits. 



REPORTS J±1<fJZ) PROCEEDINGS. 



I. — Geological Society of London. 



February 3, 1915. — Dr. A. Smith Woodward, F.R.S., President, in 



the Chair, 



The following communications were read: — 



1. " On the Gravels of East Anglia." By Professor T. McKennv 

 Hughes, M.A., F.R.S., F.G.S. 



The author discusses the sources from which the subangular gravels 

 that cover such large areas in East Anglia can have been derived. 



He points out that their great variety of fracture, colour, etc., 

 proves that they cannot have come directly from the Chalk, nor from 

 Boulder-clay derived directly from the Chalk, nor from the Lower 

 London Tertiaries, none of which contain subangular gravels, but only 

 beds of pebbles, and those mostly of small size. 



