Sergipe, and Alagoas, Brazil. 627 



Crossing the mountains (Serra do Bautista) southwest of 

 Gruna one comes out upon a great flat plateau that is deeply 

 cut by the main stream, that is by the Bio Jacare, and by its 

 tributaries, and above which rise here and there isolated peaks 

 and small mountain clusters. Following the trail from Riacho 

 Feio past the villages of Jacare, Chapada, and Carahyba to 

 America Dourada, limestone is the principal rock to be seen 

 everywhere. The beds are generally closely folded, and even 

 stand on end over large areas. Fossils were diligently looked 

 for but the only ones found were oolites apparently deposited 

 by marine alg?e.* 



On the road from America Dourada to Morro do Chapeo 

 one gets a good idea of the relations of the limestones to the 

 diamond-bearing Lavras beds that form such a large part of 

 the geology about and south of Morro do Chapeo. The sec- 

 tion where the serra merges into the plateau to the west is here 

 generalized. 



Fig. 12. 



AmeridjCL3)ou.ra_dLa. ,. 



Fig. 12. General east -west section from the plains near America Dourada 

 to near Morro do Chapeo. 



The Estancia red beds are not known in the immediate 

 vicinity of Morro do Chapeo, but south of there about forty 

 kilometers they are exposed on the upper part of Rio Salitre 

 at a camping place on fazenda Caspar and along the east side 

 of that stream to the village of Tabua, a distance of twenty 

 kilometers. At and south of Caspar the lowest rocks exposed 

 are quartzites that appear well exposed in the stream bed of 

 Rio Salitre. About 300 meters north of the camp, and appar- 

 ently resting on the quartzite is a red shaly sandstone overlain 

 by a basal conglomerate made up partly of arkose and partly 

 of waterworn blocks of a reddish crystalline rock from one 

 decimeter to half a meter or more in diameter and of blocks 

 of quartzite. The quartzites contain small granite bowlders. 



Farther clown stream (Rio Salitre) hills of pink marble fol- 

 low the direction of the road leading to Tabua. Beneath the 

 marble or other limestone beds red sandstone or conglomerate 

 occasionally crops out. The conglomerate contains both angu- 

 lar and waterworn fragments of crystalline rocks, some of 

 which are reddish granites. No fossils could be found in any 

 of these rocks. 



* Bull. Geol. Soc. America, xxii, 189-191. 



