Reviews. 



Hnssak's Geology of the Interior of Brazil. The Constitution of 

 Brazil provides (Act 3) that: "An area of 14,400 square 

 " kilometers is reserved to the Union on the central plateau 

 " of the Republic, which shall be duly laid out, and in it 

 " the future federal capital shall be established." In 1892 

 a commission was appointed to locate, explore, and report 

 upon the region referred to. Dr. Luiz Cruls, director of the 

 astronomical observatory at Rio de Janeiro, was chief, and 

 Dr. Eugene Hussak, geologist of the commission. A pre- 

 liminary report has been published under the title, Relatorio 

 parcial da commissao exploradora do planalto central do Brazil ; 

 Dr. Hussak's resume of the geology of the region is given 

 on pages 105-130. 

 In view of the little known of the origin of diamonds in Brazil, 

 what he says on this subject is of special interest. Agua Suja is a 

 diamond mine in the southwestern corner of the state of Minas Geraes, 

 four leagues south of Bagagem, the place where the famous diamond, 

 the " Estrella do Sul", was found. 



In the region between Uberaba and Rio Paranahyba the streams 

 have cut down through sandstone to the underlying highly inclined 

 mica schists. These schists contain masses and veins of quartz rich 

 in tourmalines. The horizontally bedded sandstone resting upon the 

 schist is unfossiliferous, easily decomposed, somewhat argillaceous and 

 probably of later age than Carboniferous. In some places eruptive 

 rocks (augite porphyry) overlie the schists, and in others they are con- 

 temporaneous with or later than the sandstone. The country is covered 

 almost everywhere with recent water-worn gravels, sometimes loose, 

 sometimes cemented. In the newly opened diamond washings these 

 gravels form horizontal beds more than thirty-five feet thick, and 

 divisible lithologically into four groups. The lowest of these groups 

 rests upon the sandstone, and contains the heavy materials, big water- 

 worn bowlders four to five decimeters in diameter, enclosed in fine 



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