382 



G. A. Waring — Reef Formations of the 



local differences induce weathering into more or less tinted 

 columns and into caverns.* 



The highest cliff along the northeast coast of Brazil is that 

 of Ponta Mel, between Macau and Areia Branca, the light- 

 house which stands on the point being nearly 300 feet above 

 the sea. The cliff itself forms only the upper half of the 

 point, rising above great dunes and winrows of sand, as is 



Fig. 8. 



lift. 



3,t - mi**-* ^ Sandstone 



Reef 



Reef " 



! 



8 ft. 



Brick-red sand 



Rusty -yellow .'sand 



Rust -colored ss 



DarK-red iron-cemented' ss; 



Fig. 8. Cliff sections : a, 1% miles northwest of Cabo Sao Roque ; b, 2% 

 miles northwest of Cabo Sao Roqne ; c, 2 l / 2 miles northwest of Peroaba. 



shown in figure 9. The section exposed is approximately as 

 in figure 10. Ponta Pedonda, a few miles farther west, is only 

 25 or 30 feet high. It is of mottled sandstone, mainly purple 

 in color, but with markings of lemon-yellow and of yellow 

 bordered by white. Caverns have been formed in the material, 



* The cliffs at these places are similar to those near Natal, which have 

 been described by Olaf Pitt Jenkins (Geologv of the region about Natal. Rio 

 Grande do Norte", Brazil ; Proc. Am. Phil. Soc, vol. lii, No. 211, pp. 23-25, 

 Sept.-Oct., 1913). 



