Northeast Coast of Brazil. 379 



from an inlet know as Barra do Upanema nearly to the Areia 

 Branca lighthouse, a distance of 1^ miles, by gray, lime- 

 cemented sandstone. This is composed mainly of coarse sand 

 and small pebbles. No shells were seen imbedded in it, 

 though a few seams are filled with lime-cemented shells and 

 pebbles. While it resembles the usual reef-forming material, 

 at many places it extends from the bases of dunes for a num- 

 ber of yards to the surf, and therefore is not considered typical 

 reef rock. A few fragments of the rock, more or less dis- 

 integrated, are also exposed between the dunes. 



Fig. 7. 





Fig. 7. Undercut cliff of lime-cemented sand near Fortinho. 



Morro Thibau is a hill which borders the shore about 6 miles 

 northwest of Areia Branca. Part of its coastal side is bor- 

 dered by a cliff 15 to 30 feet high, behind which sandy slopes 

 rise to a maximum height of 160 feet. A number of small 

 springs of fresh water issue along the upper border of the con- 

 solidated layer that forms the cliff. This layer is composed of 

 gray to red-brown sand in which are occasional chalky masses the 

 size of an egg. A reef of the same material borders the cliff, 

 and though it does not closely resemble the typical lime- 

 cemented reef sandstone, it appears to have a similar mode of 

 origin and to be comparable with the small cliffs .at Pontas 

 Jacare and Caicara and at Caicara light. 



At Fortinho, the port of Aracaty, gray, lime-cemented sand- 

 stone underlies cliffs of red, sandy clays, partly as a shelf at 

 about high-tide level, and partly as a low cliff which is deeply 

 undercut at one j)lace (see fig. 7.) The lighthouse at the 



