SERRA DO ESPINHAQO, BRAZIL 385 



The serra front between Chique-Chique and Lenfoes is consti- 

 tuted by a heavy series of sandstone beds dipping eastward at an 

 angle of about 30", and rising from a minimum elevation of 330™, 

 in the bottom of the valley at Passagem, to a crest line of 1,100-1,200"^. 

 Passing over the crest on the road from Chique-Chique to Santa 

 Isabel, flat-lying portions and westerly dips were observed. Westerly 

 dips also occur on the road leading northward from Lenfoes to Pal- 

 meiras, and about the latter place. The details of the structure 

 could not be worked out, but it is evident that a great sandstone 

 sheet is here bent into broad antichnal folds. Apparently the main 

 fold of the district begins with a narrow end to the northward of 

 Lenfoes, broadens out southward, and narrows down again near 

 Santa Isabel, where it becomes confused with other folds. The 

 combined valleys of the Sao Jose and Chique-Chique are excavated 



Fig. 6. — Profile of the route from the Sao Francisco to Bahia, by Mr. J. A. Allen. 



along the strike of the softer upper beds of the eastern wing of this 

 fold, laying bare a group of harder quartzitic and conglomeratic beds 

 that occur near the middle of the series. The most prominent mem- 

 ber of this group is a thick bed of coarse conglomerate that is dia- 

 mond-bearings and in consequence of the topographic disposition of 

 the strata, the entire serra front from Lenfoes to Chique-Chique is 

 marked by an almost continuous hne of active or abandoned diamond- 

 washings. 



Over the top of the plateau, which, as already stated, has a mean 

 elevation of 1,000"^ or more, .the sandstone sheet is much broken 

 up into detached blocks, as shown in the annexed outlines traced 

 from photographs, and in the view of the town of Santa Isabel w^hich 

 I owe to Dr. Henry Furniss, United States consul at Bahia. The 

 escarped margins of these blocks, and other phenomena in the dis- 

 trict, are at times suggestive of faulting, but, however important 

 this may have been in determining minor features, it is evident that 



