286 J. C. BEANNER — OUTLINES OF THE GEOLOGY OF BRAZIL 



PARAHYBA 



Previous investigations. — The geography of the State of Parahyba is 

 taken from the maps of the Inspectoria de Obras Contra as Seccas, made 

 under the direction of Dr. M. Arrojado K. Lisboa. 



The papers of Branner, Crandall, Soper, and Williamson contain 

 nearly all that is known of the geology of the State of Parahyba. There 

 are a few valuable notes made by Agassiz at Parahyba and by Burlamaqui 

 in the interior. The geologic map of this state is chiefly from the per- 

 sonal observations of the author. 



General geology. — The Brazilian complex covers all of the State of 

 Parahyba except a belt, about forty kilometers wide, along the seacoast, 

 and an infolded area, probably Cretaceous, of about twelve hundred 

 square kilometers at and west of Souza, on its western frontier. The 

 Archean rocks are cut by basic intrusives. There are some isolated 

 patches of Mesozoic or Cenozoic deposits in the mountain tops near and 

 west of Teixeira — remnants of beds that have been removed by denuda- 

 tion. The rocks of the Brazilian complex in Parahyba are mostly highly 

 inclined (50 to 75 degrees) crystalline schists, gneisses, and granites cut 

 by quartz veins in which gold has been mined. Williamson, cited in the 

 bibliography, gives a section, opposite page 116, six miles long, in the 

 Valley of Rio Bruscus. 



Along the coast is a belt of Cretaceous and Tertiary sediments that 

 nowhere exceed a width of 50 kilometers. The Cretaceous rocks are 

 mostly impure marly limestones that are exposed in the quarry at the 

 city of Parahyba and along the railway between Parahyba and Cabedello. 

 These limestones contain fossils, cephalopods, fish remains, and Crustacea 

 that indicate their Cretaceous age. Careful search has not been made at 

 other places, but it is quite probable that these Cretaceous beds extend 

 both north and south of Parahyba, though they do not appear on the 

 open coast. Owing to poor exposures, it is not possible to give the thick- 

 ness of the Cretaceous in Parahyba; the total thickness visible is only 

 about twenty meters, but neither the top nor the bottom of the series was 

 seen. 



Overlying the Cretaceous are the horizontal particolored Tertiary beds 

 that form the vertical bluffs of Cabo Branco and elsewhere along this 

 part of the coast. 



Economic geology. — Gold was formerly mined from the quartz veins 

 in the Archean area near Pianco, but the mines have long been abandoned 

 and no mines are now operated in the state. 



It is claimed that there is much iron in ParaliA'ba. but there is no 



