BRANNER: THE STONE REEFS OF BRAZIL. 243 
At Marceneiro Point coral reefs are exposed on the beach at low tide 
with the calcareous beach sands lapping over them. Inthe bank above 
the beach are exposed the partly consolidated calcareous sandstones 
shown in Fig. 58, р. 90. Porites and corallines are the commonest forms 
in the reef here. 
At the bottom of the embayment south of Marceneiro there are coral 
reefs along almost all of the beach, and soft calcareous sandstone is 
exposed in the 1 to 2.2 metres bank above it. These coral reefs rest 
directly upon Tertiary shales. 
Exa. 98. Section showing the relations of the coral reef to the Tertiary at 
Barra do Passo. 
There is a devided break in the coral reefs off the mouth of Rio Cama- 
ragibe, and they appear to begin again only five kilometres south of that 
stream. Thence southward to Ponta Verde north of Maceio the coral 
reefs are more broken and fragmentary than they are to the north. 
These fragmentary reefs were not examined except where they lie along 
the beach. Some of the beach exposures are of more than usual inter- 
est on account of their showing the relations of the coral reefs to the 
stone reefs and to the eroded Tertiary strata of the land. 
South of Rio Santo Antonio Grande the coral reefs for two or three 
kilometres are almost connected with the beach, — perhaps quite so at 
the lowest tides. 
At the point 1.4 kilometres south of Rio Sapucahy there is a sandstone 
reef overlying the coral reef. In view of the importance of this locality 
in showing the geologic relations of the stone and coral reef, I repeat 
here what has been given in the description of the Sapucahy stone reef: 
“Following the beach southward from the mouth of the Sapucahy 
[a small river of the State of Alagóas about thirty kilometres northeast 
of Maceio] it curves gradually seaward and then back landward again, 
forming a sandy point, part of which is shown on the accompanying 
map. Ata distance of 1.4 kilometres from the mouth of the Sapucahy, 
this sandy point laps over one of the coral reefs that here run parallel 
with the coast. And just at this point on the beach begins another 
