BRANNER: THE STONE REEFS OF BRAZIL. 139 



South of Cabo Santo Agostinho the great sandstone reef stretching 

 from the Barra do Suape at the old fort on the cape to Cupe, a distance 

 of twelve kilometres, shuts in another old embayment into which still 

 drain the Suape, the Tatudca, the Ipojuca, 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 Xorte. 

 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 Brauco itself. 



The Cunhahu River in Rio Grande do Xorte 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 Cunhahu 

 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 Eio 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 pi-esent some such out- 

 line as that shown in the accompanying cut. 



Fig. 76. Type 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 



