/'^PR 21 1916 



PROCEEDINGS 



OF THE 



AMERICAN PHILOSOPHICAL SOCIETY 



HELD AT PHILADELPHIA 

 FOR PROMOTING USEFUL KNOWLEDGE 



THE GEOLOGY OF PARAHYBA AND RIO GRANDE DO 

 NORTE, BRAZIL. 



Plates I-IV. 

 By RALPH H. SOPER. 



(Read December 3, 191 5.) 



Table of Contents. 



Page 



Introductory i 



Topography 3 



Coastal sediments 3 



A great plateau of crystalline rocks 4 



A series of high tables-lands and serras 4 



Drainage 5 



Geology 6 



The Brazilian complex 6 



The sedimentary series 8 



Sandstones 8 



Limestones 9 



Sands and clays 1 1 



Isolated sandstone areas i4 



Summary of observations on the geology of Parahyba and Rio Grande 



do Norte 16 



Introductory. 



The data for the following paper was gathered in a series of 

 three expeditions made into the states of Parahyba and Rio Grande 

 do Norte. The actual time consumed in collecting the material 

 dated from the latter part of March, 1912, until the middle of 

 February, 1913. The writer was sent into the field by the Brazilian 



PROC. AMER. PHIL. SOC. , VOL. LV. A, PRINTED MARCH 28, I916. 



