BRANNER-AGASSIZ EXPEDITION TO BRAZIL 187 



above high tide level. It is possible that there is a little higher 

 ground at the city of Caravellas. At Ponta d'Areia the highest 

 ground is onl}^ one meter above high tide. Changes of level 

 over the surface of the plain are usually either very gentle or 

 very abrupt, the slopes being long, even, and imperceptible on 

 one side and dropping off abruptly on the other. The soil of 

 this coastal belt is all sandy. At the surface it is blackened by 

 the decay of vegetation, but from two to six decimeters beneath 

 the surface this sand is of various shades of yellow — sometimes 

 almost orange colored. It is worthy of note in this connection 

 that the great sand bars off the mouth of the Caravellas River 

 have about the same yellow color. At many places where pits 

 have been dug for wells in these sands of the coast belt, large 

 quantities of marine shells have been thrown out, while at other 

 places ants and other burrowing animals bring these shells or 

 their fragments to the surface. At two places I found pieces 

 of coral in the sand from such pits. One of these was a frag- 

 ment of HeliastrcBa a-perta as big as one's fist, a coral growing 

 abundantly on the great coral reefs off the coast. The other 

 form was a small specimen of the little Astrangia solitaria. 

 Oysters and other bivalves, worm tubes, and gasteropods are 

 abundant in this sand. The molluscan remains found in the 

 sands of this coast plain look very like the forms now living 

 along the coast, but in the absence of collections of both the 

 fossils and of the existing coast fauna no opinion can be ex- 

 pressed in regard to the precise geologic age of the coast plain. 

 It may be either Pliocene, Pleistocene, or recent. 



Beyond kilometer ten the railway passes gradually from the 

 low sandy coast plain into open sandy campos. The loose 

 sands along this portion of the line are white and have the ap- 

 pearance of having been leached by acidulated waters. The 

 country is nearly flat and only a little higher than the coast 

 plain. The only rocks visible are soft black sandstones exposed 

 in the trenches beside the railway track. Similar sandstones 

 are found at many places along the northeast coast of Brazil, 

 always at a low level, usually black to snuff-colored, and 

 wherever their relation to the adjacent rocks is apparent, they 

 rest unconformably against and upon the eroded Eocene (?) 



