WORKS ON GENERAL GEOLOGY . 199 



features of Brazil that will bring the subject up to date. I am unable to 

 give the title of the work, however. 



WORKS ON THE GENERAL GEOLOGY 



There are but few books on the general geology of Brazil. Hartt's 

 Geology and Physical Geography of Brazil, published at Boston in 1870, 

 was the first considerable work treating of the geology of Brazil as a 

 whole. The book is now long out of print, but copies are occasionally 

 offered by dealers, and it can be found in most of our large libraries. 



The article by H. Gorceix, in '^'Le Grande Encyclopedic,^^ chapter IV 

 of the second edition, Paris, 1889, is a short but good one on the general 

 geology of Brazil. 



In 1906 Branner's Geologia Elementar was published in Portuguese at 

 Eio. This work was meant for a text-book for the use of Brazilian stu- 

 dents, but the third part contained a resume of the geology of Brazil. 

 The second edition of this book was published in 1915, and the third 

 part, on historical geology, gives brief statements of the distribution of 

 rocks of different ages wherever they are known, and the footnotes refer 

 to the authorities. 



Eodolpho von Ihering, in his little book entitled "Landeskunde der 

 Eepublik Brasilien,'^ Leipzig, 1908, gives at pages 17-27 a sketch of the 

 broad features of the geology of Brazil. It is a brief but good compila- 

 tion from some of the best sources. 



GEOLOGIC MAPS OF BRAZIL 



Several attempts have been made to produce geologic maps of Brazil, 

 but in most cases the maps have been on very small scales, and the geology 

 has been represented by broad generalizations and necessarily based on 

 very limited knowledge. 



One of the difficulties any one encounters who undertakes such a map 

 is the impossibility of correlating the geology of one area with that of 

 another. This is difficult or quite impossible, even for those who do the 

 field-work itself; but when one tries, from data gathered by two or more 

 different geologists, to reconcile their differences of interpretation, and 

 to correlate when the data for correlation are not available, it is clearly 

 impossible to obtain results satisfactory to one's self or to others, espe- 

 cially if nice discriminations are attempted. 



A. D'Orligmj, 181^2. — The first geologic map of Brazil seems to have 

 been one forming part of the ^^Carte de I'Amerique Meridionale indiquant 

 ses differentes epoques geologiques, par A. D'Orbio-ny." dated 181:2 and 

 published as plate X of "Voyage dans PAmerique Meridionale, . . . par 



