358 Prof. HiVtt on the Brazilian Sandstone Reefs. [June, 



in texture, and contains numerous fragments of corals and shells, 

 the latter being frequently found entire. Many of the species of 

 both exist in abundance throughout the bay. The upper part of 

 the cliff is of almost pure sand, and has been so incompletely hard- 

 ened as to crumble readily between the fingers. The amount of 

 calcareous material in the lower portion is very great, and it is 

 said to yield a good quality of lime on burning. 



Whether this cliff belongs to the same class of structures as. 

 the reefs or not, it is, at least, composed of the same materials, 

 and must have been formed in about the same way. Its present 

 elevated position — for high water reaches only slightly above its 

 base — indicates that the shore has been raised at this point to a 

 height nearly equaling that of the cliff What gives an increased 

 interest to this locality is the presence of a low kitchen-midden, 

 only two or three feet thick, which overlies the entire cliff It is 

 composed of a dark-colored, sandy earth, packed full of the 

 shells of the edible mollusks of the bay, with a few scattered 

 bones, and occasionally a human skeleton. 



The stone reefs of the southern part of the province of Bahia, 

 have been very fully described by Prof Hartt, in the " Geology 

 and Physical Geography of Brazil." The principal ones are those 

 of Porto Seguro and Santa Cruz, both being similarly situated 

 and of about the same character. The former is the larger, and, 

 beginning in front of a small bay formed at the mouth of a river, 

 runs southward, skirting: the shore for a long distance. In gen- 

 eral structure it is like the Pernambuco reef; the outer edge has 

 become very jagged, from the undermining and falling down of 

 'blocks. But below the level of low water, the reef-rock extends 

 seaward a hundred feet or more, forming a very shallow tract, 

 over which one may wade when the tide is out. The inner edge 

 is much thinner than the outer, being often overhanging, and it 

 is flanked by a sloping bank of mud. The surface is of very 

 uniform height, but quite rough, and interrupted by cracks and 

 pools, which teem with marine life. From fractures at the end, it 

 is apparent that the hardening has taken place to a depth of sev- 

 eral feet below low tide. 



At Gaurapary and Barra Secca, in Espirito Santo, and in their 

 vicinity, are several imperfect reef formations, similar to many 

 already described; and at the Abrolhos islands, as before stated, 

 the sand and shingle beaches are often firmly consolidated by a 

 lime cement. 



