Revieivs—Tlie Mineral Dej)osits of South. America. 335 



information contained in these pages is astonishing, and though 

 written in somewhat more prosaic style than the stories of the early 

 adventurers, it is equally interesting, perhaps more so to an economic 

 geologist, since the romance is here founded on fact. 



The first chapter contains an admirable description of the general 

 physiographical and geological features of South America, with a 

 discussion of tectonics and their bearing on the problems of 

 mineralization. The country is divided into eight districts — the 

 Guianan Highlands, the Brazilian Highlands, the Cordilleras, the 

 Llanos and the plains of the Orinoco, the jolains of the Amazon, 

 the plains of the Paraguay and Parana, the Patagonian Pampas, 

 and the coastal plains. Nearly all the economic minerals are 

 contained in the first three. 



Each of the succeeding eleven chapters contains a full and com- 

 prehensive account of the economic geology of one of the South 

 American States, a large part of the information being the result of 

 personal observations by the authors, especially in Brazil, Chile, 

 Bolivia, and Peru, and in part in Argentina, Ecuador, and Uruguay. 

 Each chapter closes with an admirable bibliography, which in some 

 cases include over 200 items. This is an invaluable feature of the 

 book. 



Among so many jDoints of interest it is difficult to make a selection 

 for special mention. One of the most fascinating chapters is that on 

 Bolivia, where the rich silver-tin-tungsten mineralization naturally 

 comes in for a large share of attention, both on account of its 

 intrinsic value and for its theoretical significance. It is refreshing 

 to read a clear and coherent account of these important deposits 

 as they really are, freed from the absurd generalizations of the 

 Freiberg school. The Bolivian silver-tin dejDosits seem to form a 

 well-authenticated example of the occurrence of tin and tungsten 

 in quantity in connexion with Tertiary igneous activity. It is 

 noteworthy, however, that as soon as the frontier of Argentina 

 is crossed the minerals are clearly associated with Palseozoic 

 granites. Hence we have here an instance of the occurrence of a 

 similar type of mineralization in two neighbouring areas at two 

 widely separated periods of time. It is as yet too early to say 

 definitely whether there is any overlap of these two mineralizations 

 in space. 



A very full account is given of the iron and manganese resources of 

 Brazil ; the former are undoubtedly enormous, some good 

 authorities having estimated the reserves of haematite in the State 

 of Minas Geraes alone at 12,000,000,000 tons. This is probably 

 excessive, but it is clear that Brazil contains the most important 

 undeveloped deposits of iron-ore of any country in the world. 

 However, development is hindered by difficulties of transport, owing 

 largely to the absence of important coalfields and the remoteness of 

 the iron districts from the coast The magnetite ores of Jacupiranga, 

 described by Derby, are of great petrographic interest, since they are 



