2 SOPER— GEOLOGY OF PARAHYBA 



government to investigate the practicability of drilling wells and 

 procuring water throughout the two states mentioned above. The 

 notes on the geology were made in connection with and as a part of 

 that work. 



The topography of Parahyba and Rio Grande do Norte is not 

 one of strong contrasts. There are no great mountain ranges and 

 no large rivers. In fact there is not a single stream in either state 

 that can be depended upon to flow during the entire year. The 

 climate, for the most part, is hot and dry — a somewhat unexpected 

 phenomenon for a region in 5 degrees south latitude. The rain- 

 fall is irregular, being copious one year while the next it may fail 

 entirely. Moreover, it is seldom distributed over a considerable 

 time or area, but is more likely to fall locally in a torrent, and then 

 after a dry period of weeks, there is another torrent. 



The states of Parahyba and Rio Grande do Norte have com- 

 paratively few inhabitants and their struggle for life during the 

 last 200 years forms one of the epics of South America. Driven 

 from their homes time after time by thirst and hunger, they have 

 always returned and are still in the sertao,^ enduring untold priva- 

 tions and waiting with infinite patience the arrival of happier times. 



The topography of the accompanying map is based on the 

 " Mappa dos Estados do Ceara, Rio Grande do Norte e Parahyba," 

 by H. E. Williams and R. Crandall. With the exception of the 

 coastal sediments south of Natal, which are shown according to 

 J. C. Branner, the geology is the writer's own work. The region 

 covered is an extensive one and the work was done by means of 

 horseback meanders, a pedometer, pocket compass, aneroid, and 

 hand level. In general, however, the geological areas shown are 

 accurate within the map scale used. 



The writer wishes to acknowledge his indebtedness to Professors 

 J. C. Branner, Orville A. Derby, and to Dr. M. Arrojado Lisboa, 

 for valuable help and suggestions. Among the papers consulted, 

 two were found to be of especial value, namely, " The Geology of 

 the Northeast Coast of Brazil," by J. C. Branner and ".Geographia, 

 Geologia, Supprimento d'Agua, Transportes, e Agudagem," by 

 Roderic Crandall. 



1 " Sertao " is the word used in northeastern Brazil to denote the back 

 country or the interior. 



