192 Annals of the Carnegie Museum. 



The serras to the northwest and southeast of Angicos have nearly 

 horizontal cappings of Cretaceous sandstone, but from near Angicos 

 the underlying gneiss or schist seems to dip westward at twenty to 

 thirty degrees. Halfway between Angicos and Pau dos Ferros the 

 strike of the gneiss seems to swing from westerly to southerly. In the 

 vicinity of Pau dos Ferros the rock seems to be mainly granitic gneiss, 

 but no good exposures showing the strike were observed. For some 

 distance to the southwest the rock seems also to be granitic gneiss; 

 but six or eight kilometers from the city there is a belt of hornblende 

 rock, succeeded by mica-schist. The gneiss also extends for some 

 distance southeast of the city, but at the crossing of Rio Apody, seven 

 kilometers away, the rock is extensively decomposed into a white 

 kaolin-like clay. The strike here is nearly south, with steep west dip. 

 A few kilometers to the east, however, the dip seems to swing to 

 nearly north. Near reservoir Corredor, thirty-five kilometers south- 

 east of Pau dos Ferros, the main rock is decomposed granitic gneiss, 

 with a prominent granitic hill three kilometers to the southwest. 

 Near the reservoir green (chloritic?) garnet gneiss was noted, and both 

 there and at the base of the granite hill there is much hornblende. 

 Thence southward the rock is granitic to and beyond Barriguda. 

 Serra da Barriguda contains prominent, nearly barren granitic peaks, 

 which give the range a markedly saw-tooth profile. Near the south 

 base of the range the rock is very porphyritic, with feldspars up to 

 two centimeters in length. Near Jerico the rock is more gneissic, 

 with pegmatite dikes and a small amount of chlorite (?) schist. In 

 the river channel a short distance north of the village a dark biotitic 

 rock is exposed for two hundred meters. Thence to Pombal the rock 

 is gneissic or schistose, with dikes of pegmatite and dark areas, which 

 seem to be due to the segregation of hornblende and biotite. From 

 Pombal to Curema the rock seems to be all schistose, the dip being to 

 the north and increasing from about thirty degrees near Pombal to 

 nearly vertical near Curema. The rock also become? more thinly 

 laminated as one approaches Curema. The range, composed of the 

 serras of Vital, Santa Catharina, and Melado, forms a remarkably 

 straight, east-west ridge, composed in part of white, granular quartzite, 

 carrying muscovite. Near Curema the Rio Pianco cuts northward 

 across the range and exposes the rock dipping nearly vertically south- 

 ward. At Rio Aguiar, five kilometers west of Curema, there are 

 apparently four ledges of quartzite, and it seems as if the range here_ 



