Waring: Geology of Northeastern Brazil. 217 



and the position and character of the gravels point toward the action 

 of water. 



Between Campina Grande and Soledade much angular to sub- 

 angular quartz-gravel is scattered over the surface and is derived from 

 numerous quartz-veins in the gneiss.^^ 



North of Periquitos the surface is covered with much angular gravel, 

 which is probably derived from pegmatite dikes, which are abundant 

 in the locality. 



For two or three kilometers south and west of Jardim de Serido 

 unassorted, but fairly well-rounded, quartz-gravel covers the surface. 

 In places it is mixed with angular material, which looks as if it were 

 disintegrated in place. The rounded material seems to form a thin 

 layer over lands which are well above present stream-channels. 

 Northeast of Jardim de Serido angular quartz-fragments up to ten 

 centimers in dimensions are scattered over the surface; and in several 

 places, notably at six, ten, eleven and eighteen kilometers from the 

 town, belts of unassorted, but rounded, gravel form thin layers over 

 the gneiss. The northernmost belt, fifty meters wide where crossed 

 by the road to Acary, is on land forming a plateau. Westward from 

 Acary there is a thin layer of angular white quartz fragments over 

 much of the surface. About sixteen kilometers west-southwest of 

 Acary the road passes for nearly half a kilometer over a belt of rounded 

 gravel on low plateau land above the river-channel. About thirty- 

 three kilometers southwest of Acary another similar belt, or possibly 

 the extension of the same belt, half a kilometer wide, is crossed by 

 the road. Much, if not all, of the quartz-gravel of the vicinity may 

 be derived from the numerous quartz and pegmatite ledges; but some 

 cause other than simple disintegration would seem necessary for the 

 production of the wide belts of rounded material. It is possible that 

 what seemed to be wide bands of gravel were places where the road 

 follow^ed nearly along narrow bands through the dense scrub; but it is 

 improbable that the road would have been deliberately cut along 

 such paths of rough going for beasts of burden. 



In the lowland along Rio Apody near Mossoro several bands of 

 quartz-gravel were crossed, the relation of which either to the present 

 stream-channel or to the adjacent bluffs of Cretaceous limestone was 

 not clear. 



■'■' Crandall (Publ. No. 4 of the Inspectoria, p. 29), noted these gravels, but he 

 seems to have associated them with sedimentary deposits in a Cretaceous basin 

 In Serra do Teixeira, to the southwest. 



