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BRANNER: THE STONE REEFS OF BRAZIL. 139 
South of Cabo Santo Agostinho the great sandstone reef stretching 
from the Barra do Suäpe at the old fort on the cape to Cape, a distance 
of twelve kilometres, shuts in another old embayment. into which still 
drain the Suäpe, the Tatudca, the Ipojüca, and the Merepe rivers. The 
hills that bound this ancient embayment start with the cape, swing 
inland many miles, and reach the coast again only near Ponta do 
Serramby. Within this embayment are a few isolated hills that 
formerly made islands in the shallow but now silted up bay. 
The Rio Parahyba, in its lower course, now flows through a silted up 
bay that once extended south and west of the city of Parahyba do Norte, 
Seen from the upper city, this old bay is now represented by the cane- 
fields, marshes, mangues, and sluggish streams of the Parahyba valley. 
The filling up has progressed so far that the sands have filled far beyond 
the old mouth of the bay, and the newly made. sand-flats of Cabedello 
extend to the base of the hills on which Parahyba stands, and almost to 
Cabo Branco itself. 
The Cunhahú River in Rio Grande do Norte is the last remnant of a 
bay that formerly opened between the hills of Cabo Bacapory and Bahia 
Formosa on the south and the hills at the base of which the Cunhahú 
now enters the sea. This was a long narrow bay that extended many 
miles inland. Many similar streams along that part of the coast are now 
characterized by lakes of considerable size in the process of transforma- 
tion into marshes or dry land. 
Depressed valleys. — A. characteristic feature of the coast of Brazil 
from Rio Grande do Norte to Prado, in the southern part of the State 
of Bahia, is the topography about the streams where they debouch upon 
the coast. Seen from the ocean, they generally present some such out- 
line as that shown in the accompanying cub. 
Fro. 76. Туре of submerged and silted coast valley. 
Such forms are quite in keeping with the theory herein maintained. 
The present river valleys were cut out when the land stood at a higher 
level; when the depression took place these valleys were partly sub- 
merged, and in the course of time their shallow mouths have been. 
