Reviews — Hmifs Geology of Brazil. 529 



very brief notice of Prof. Hartt's book ; we will therefore gather a 

 few of the geological results it makes known. 



The oldest (Eozoic) rock observed appears to be fundamental 

 gneiss. Gneiss is found in every province of the Empire. It forms 

 the great coast-belt extending from MaranhSo to the mouth of the 

 Rio de la Plata, but it sends off a band from southern Minas Geraes 

 into Goyaz, and the Montes Pyrenees, and a considerable part of the 

 mountainous region of Central Goyaz are composed of it. The 

 same rock is seen in the cataracts of the Tocantins, the Xingu, the 

 Tapajos, the Arinos, and the Madeira, showing that the Table-land 

 of Brazil is everywhere underlaid by it. 



As these rocks are highly inclined and full of reversed folds, as 

 in Canada, it is quite impossible to approximately estimate their 

 thickness. 



Dr. T. Sterry Hunt, who has examined with care a large suite of 

 Prof. Hartt's specimens of metamorphie rocks, considers that they 

 " present the characteristic types of the Laurentian of North America, 

 including as they do coarse granitoid and porphyritic varieties, 

 with red orthoclase and fine-grained grey and white-banded gneisses, 

 often hornblendic. The white crystalline limestone, with pale green 

 serpentine, which occurs with these Brazilian gneisses, is not dis- 

 tinguishable from that of the North American Laurentian." 



Dr. Hartt believes that the clay and talcose schists, the itacolumite. 

 itabirite, and other associated metamorphie rocks of the gold-region, 

 of Minas Geraes, are of Lower Palaeozoic age (Silurian), and he 

 suggests that they may be equivalent to the Quebec group of North 

 America. 



Clay-slates, with auriferous veins, occur in other parts of Brazil 

 besides Minas, as, for instance, in Goyaz, and in the vicinity of 

 Cuiaba in Matto Grosso. These rocks are everywhere so metamor- 

 phosed, that all trace of fossils has been completely obliterated. 



Some of the metamorphie rocks of Minas Geraes or Bahia, the 

 author thinks, may be Devonian, but he saw no rocks referable to 

 that age upon the coast, unless, indeed, the slate conglomerates, 

 sandstone, and shale, with fossil plants, found on the Eio Prado, may 

 belong to it. 



There can be no uncertainty about the existence of true Carbon- 

 iferous strata in Brazil, for besides the Coal, we have an abundance of 

 fossil plants of Carboniferous genera. The true age of the Brazilian 

 Coal-beds on the Rio Candiota, Rio Grande Do Sul, explored hj Mr. 

 N. Plant, P.G.S., was satisfactorily determined on the evidence of 

 the plant-remains by Mr. W. Carruthers, F.L.S., P.G.S., of the British 

 Museum (See Geol. Mag., 1869, Vol. YI. p. 151, Plates V. and VL), 



The Coal-basins lie just south of the tropics, but within the range 

 of the palm, and they are a coast-formation, corresponding in this 

 respect to the Coal-basins of Acadia, Massachusetts, and Rhode 

 Island. Coal-strata do not seem to occur north of Rio on the 

 coast. The beds of Coal appear to have been but very slightly dis- 

 turbed, and to be bituminous in character. 



A large area in the Province of Sergipe is occupied by a thick 



