REVIEWS 753 



Trias. Above these lie Jurassic, Cretaceous, some small patches of Ter- 

 tiary strata, and, on the higher elevations, glacial deposits. 



The pre-Cambrian rocks and the intruded gabbro are the most impor- 

 tant from the standpoint of the economic geologist, for it is with these that 

 the ore deposits are connected. 



As indicated by the title of the paper, copper ores are the chief ores of 

 this district, though some lead and silver, and a trifling amount of gold, in 

 quartz veins, have been found. The copper minerals comprise chalco- 

 pyrite, bornite, chalcocite, and covellite, with their usual alteration products. 

 The principal gangue minerals are quartz, calcite, siderite, feldspar, horn- 

 blende, epidote, and garnet. 



Some of the metallic sulphides crystallized contemporaneously with the 

 silicate minerals of the rocks; others are supposed to be of later origin, and 

 to have been formed by impregnation of the schists by the intrusive norite. 

 A common origin by aqueous deposition is assigned to the remaining ores, 

 and they are found in all channels of easy circulation. Their ultimate 

 source is attributed to the basic igneous rocks of the region, which contain 

 appreciable amounts of copper, and in many cases cobalt and nickel as well. 



The most important ores commercially are those (chalcocite) found 

 along the bedding planes and brecciated zones in the pre-Cambrian 

 quartzite. Here secondary enrichment has taken place. 



W. D. S. 



Recent Seismological Investigations in Japan. By Baron Dairoku 

 KiKUCHi. Private Publication. 



This important paper was prepared as an address to be delivered at 

 the Congress of Arts and Science at St. Louis, but, as the author was 

 unexpectedly prevented from attending the Congress, it was printed pri- 

 vately and distributed by him. It is, however, a much more elaborate 

 paper, and much more amply illustrated, than would be inferred from the 

 statement that it is an address. It covers 145 pages, and is accompanied 

 by 54 illustrations relating to earthquake effects, earthquake-proof struc- 

 tures, instruments of observation and their records, geographic distribu- 

 tion, and related subjects. The paper sets forth with much fulness the 

 work of the Earthquake Investigation Committee of Japan in connection 

 with the Seismological Institute of the Tokyo University — work which 

 must be regarded as among the most important now in progress. A chapter 

 is given to the geographical and chronological distribution of eai thquakes — 



