206 Annals of the Carnegie Museum. 



river the strike seems to be westward, with nearly vertical north dip, 

 but at the river the rock dips steeply to the northwest. 



Northwestward from Alagoinhas gneiss is first seen near Agua Fria, 

 whi(?h marks the western limit of the coastal sediments, where crossed 

 by the railway, but the first good exposure, showing structure which 

 was noted, is near Lamarao, where the dip seems to be gently west- 

 ward, and continues thus nearly to Serrinha, where the dip is south- 

 ward. Between this place and Salgada there seems to be considerable 

 variation in the direction of strike. This may be in part due to error 

 in the observation of low dips and to the wavy character of the 

 foliation planes; for, as the dip becomes steeper, the strike seems to 

 become more uniform northwestward. North of the railway along 

 this stretch there is a considerable area of porphyritic granite. Where 

 it is crossed by the main road between Serrinha and Aracy the granite 

 is ten kilometers wide, extending from one kilometer south of Pedra 

 to within nine kilometers of Aracy. On the north and south it is 

 bordered by zones of crushed gneiss, which contains much quartz. 

 Similar crushed material, which carries much quartz and feldspar, and 

 is traversed by dark bands rich in hornblende and black mica, out- 

 crops one kilometer southwest and south of Aracy and exhibits steep 

 west dip. About five kilometers west of Aracy less crushed phases of 

 this material are traversed in all directions by narrow pegmatite dikes 

 which consist of feldspar and quartz, with very little mica, horn- 

 blende, or tourmaline. 



At Santa Luzia the gneiss dips steeply to the southwest. Near this 

 town there are several prominent hills of gray granite, and thence for 

 several kilometers along the railroad the rock is all granitic. Half- 

 way to Queimadas it becomes gneissic again, but with dip to the north- 

 east, instead of to the southwest, as at Santa Luzia. Unless there is 

 other folding these dips indicate that the granite is in a synclinal fold. 

 At Queimadas the gneiss dips west at an angle of twenty degrees, but 

 thence northwestward the dip steepens as Serra da Itiuba is ap- 

 proached. The south end of this serra is crossed by the railroad, 

 along which the strike of the gneiss flanking the range on each side 

 is north-south, conformable with the trend of the latter. This struc- 

 ture continues northwestward along the railroad with little inter- 

 ruption, to the vicinity of Jaguarary, where granite is exposed for a 

 few kilometers. Near Ituniirim a small exposure of gneiss shows the 

 usual north-south strike, with vertical dip. The region between 



