314 NOTES OF A NATURALIST. 



range. The outlines were in most places rouncjled and 

 covered with vegetation, but at intervals occurred 

 steep conical masses, of the same general type as the 

 sugar-loaf peaks surrounding the Bay of Rio Janeiro. 

 However steep, the rocks nowhere showed angular 

 peaks or edges, these being always more or less 

 rounded. 



It would be rash to generalize from the partial 

 observations of a passing traveller; but the broad 

 outlines of the geology of Brazil, or, at least, of the 

 eastern provinces, have now been well traced,* and 

 some general conclusions may safely be drawn. It is 

 true that large districts of the interior have been but 

 partially explored, and remain blanks on the geological 

 map ; but the eastern half of Brazil is undoubtedly 

 ancient land, presenting no trace of secondary strata 

 except in small detached areas near the coast, and 

 where more recent tertiary deposits are to be found 

 only in a portion of the great valley of the Amazons. 

 A mountain range, having various local designations, 

 but which may best be called the Serra da Manti- 

 queira, extends from the neighbourhood of San Paulo 

 to the lower course of the Rio San Francisco, for a 

 distance of twelve hundred miles, and this is mainly 

 composed of gneiss, sometimes passing into true 

 granite, syenite, or mica schist ; and the same may 

 be said of the Serra do Mar, a less considerable range 

 ' lying between the main chain and the coast. The 



* The best general account of the geology of Brazil that I have seen 

 is contained in a short paper by Orville A. Derby, entitled, " Physical 

 Geography and Geology of Brazil. " It was published in the Rio News, 

 in December, 1884, and, through the kindness of Mr. Geikie, I have 

 seen a reprint in the library of the School of Mines. 



