GENERAL AND ECONOMIC GEOLOGY 225 



J. W. Evans : The rocks of the cataracts of the River Madeira, etc. Quarterly 



Journal of the Geological Society, volume LXIl, pages 88-124. London, 



1906. 

 G. GtJEicH : Gryposuchus Jessei, ein neues schmalschnau ziges Krokodil aus 



den, etc. Jahrbuch der Hamburg! schen Wissenschaften Anstalten, volume 



XXIX, 1911, pages 59-71. Hamburg, 1912. 

 Franz Keller: The Amazon and Madeira rivers. Sketches and descriptions 



from the note-book of an explorer. By Franz Keller, engineer. 4°, xvi + 



177 pages. New York, 1874. Notes on the geology. 

 EuzEBio Paulo de Oli^teira : Expedigao Scifmtifica Roosevelt-Rondon. Annexo 



I, Geologia. Rio de Janeiro, 1915. (Estrada de Ferro Madeira-Mamore, 



paginas 61-65.) 



ALAGOAS 



Previous investigations. — Very little has been published on the geology 

 of the State of Alagoas. Of the three papers by Branner the most com- 

 prehensive is the one on the geology of the coast of the State, publishe'^ 

 in the Annals of the Carnegie Mnseum. The paper by D. S. Jordan on 

 the fossil fishes froniEiacho Doce definitely determined the Eocene age 

 of the coastal sediments of that state for the first time. Branner's paper 

 on the oil-bearing shales of the coast includes about all that is known of 

 the Tertiary of the state. A few notes in Hartt's Physical Geography 

 and Geology of Brazil, and a few by Burlamaqui on the shales at Cama- 

 ragibe, together with the papers above mentioned, contain all that has 

 been published on the geology of Alagoas. 



The geology as given on the author's map of Brazil is taken almost ex- 

 clusively from his own personal observations, supplemented by the notes 

 of his assistant, Eoderic Crandall, who crossed the state from Penedo to 

 Maceio in 1908. 



General geology. — Archean rocks are exposed over the greater part of 

 the interior of the State of Alagoas. Tertiary sediments form the sea- 

 coast, while between is a triangular area of old Paleozoic and Permian 

 beds. Starting at Traipu, on the Rio Sao Francisco, the eastern margin 

 of the Archean area runs in a northeasterly direction past the northern 

 end of Lagoa Manguaba, Albuquerque, Passo, and Porto Calvo, and so 

 on into the State of Pernambuco near Barreiros. To the north and west 

 of this line everything is Archean except some isolated hills of sedimen- 

 tary rocks near the falls of Paulo Affonso. 



Lapping back against this Archean area is a series of Paleozoic rocks 

 of unknown age. This series is exposed where it is cut across by the Eio 

 Sao Francisco from near Traipu to southeast of the town of Collegio. 

 The contact of the sedimentary beds with the granite seems to be at Tal- 

 hado near Traipu.*^ This Paleozoic area forms an acute triangle whose 



*5 R. F. Burton : Explorations, etc., vol. 11, p. 423. London, 1869. 



