Northeast Coast of Brazil. Z^ll 



part of the coast, however, are in several places situated in 

 suggestive relation to existing areas or lagoons or marsh land, 

 shut off from the sea by dunes of sand. This seems to be 

 shown near Rio do Fogo (fig. 3c), and also near Ponta Reducto. 

 At the latter place the present position of lagoons, as shown 

 by figure 6, is evidently determined by the shifting sands ; 

 and conditions might easily have been such as to cause the 

 water to find outlet in the vicinity of the present reef. 



All of the well-developed reefs noted by Dr. Branner south 

 of and including Rio Grande do Norte are opposite the 



Fig. 5. 











Caifara \Jj* 



Santa c *~ 

 Maria. ^ 



L L 

 i 



c c c 



Z Miles 



c ^ 



c l 

 c " v 



Pta.Caicara— T ^z-=r^' 



A- 



9 



c 



h. 



'(. 













Fig. 5. Belation of lithified beach to present beach, near Ponta Caigara. 



mouths of rivers of considerable flow. In the light of the 

 origin of the reefs, the absence of such well-developed off- 

 shore reefs farther north may, therefore, be safely ascribed 

 chiefly to the absence of suitable streams for their formation ; 

 for the weak flow of fresh water seaward has apparently been 

 able to harden masses of sand only along the beach. In some 

 places, however, these consolidated beaches have been encroached 

 upon by the sea, so that they now form off-shore reefs. 



The apparent greater frequency of reef remnants along the 

 shore northwest of Touros than southward from that place is 

 perhaps due directly to the curving of the coast line in this 

 vicinity to a more northwesterly course. This brings the 

 beach line more nearly parallel with the direction of the pre- 

 vailing wind and hence induces slight alteration of the beach 

 line by the drifting sand. The best example of this phenomenon 

 that was noted is in the vicinity of Ponta Caicara, and has 

 been already described. 



