Waring: Geology of Northeastern Brazil. 205 



rapid variation in the direction of strike of the foliation planes indi- 

 cates contortion, notably in the mountainous area between Quix- 

 eramobim and Cratheus, where the ranges also have various trends. 

 In general, however, both the strike and the dip seemed to the writer 

 to be fairly constant over considerable distances, and it seemed that 

 it would be easily feasible to work out the major foldings in the base- 

 ment series. Most of the region is covered with a dense growth of 

 small, thorny trees and tall cactus, and in very few places would it be 

 feasible to follow geologic contacts; but pack-trails which have been 

 cut through this growth connect all the numerous small settlements, 

 and by traversing them a sufficiently good network of meander lines 

 would probably be obtained to permit the mapping of the geology with 

 fair accuracy. 



Structure South and West of Recife. Satisfactory notes on the bed- 

 rock structure along the railway from Recife to Maceio were not 

 obtained by the writer, and the line west from Recife was not tra- 

 versed. Observations along these lines have been published by Dr. 

 Branner.2* 



The structure exhibited along the railway line, running westward 

 from Recife shows nearly uniform east-west strike, with steep dips to 

 north or to south, between Recife and Antonio Olyntho. East-west 

 strike is also shown along the railroad southward as far as Gamelleira. 

 From there to Marayal the strike is to the southwest. Westward 

 from Marayal there seems to be an area of much crumpling. 



Structure in the Southern Area. A wide area of sedimentary rocks 

 extends northward inland from the city of Bahia, but along the valley 

 of the Rio Itapicurii granite is exposed. Along the railway it first 

 appears five and a half kilometers northward from Apora. Near the 

 river gneissic phases exhibit steep south dips. In the cut a jshort 

 distance north of the river a vertical band of serpentine is exposed, 

 and a little farther north the gray granite is traversed by nearly 

 vertical stringers of quartz and pegmatite. In one place rounded 

 boulders, produced by concentric weathering, are in evidence. The 

 plateau in the vicinity of Barracao is capped by sedimentary materials, 

 but three or four kilometers beyond the town granitic gneiss appears 

 in the descent to Rio Real. Half-way between the town and the 



^'i Geology of the Northeast Coast of Brazil, Bull. Geol. Soc. Amer., VoL XIII, pp. 

 41-98; Proc. Wash. Acad. .Set., Vol. II, pp. 195-201, and Am. Jour. Sci., Feb., 

 1902. 



