8 



Annals of the Carnegie Museum. 



and south, might naturally be expected to contain rocks of both Cre- 

 taceous and Tertiary ages. Unfortunately but little geologic work has 

 been done in the state of Alag6as, and this little has not hitherto yielded 

 unquestionable evidence of the age or ages of the sedimentary beds in 

 that particular state, while the somewhat conflicting nature of the evidence 

 which might be adduced from neighboring regions makes it impossible to 

 use that evidence to settle the question. In order to determine the age 

 or ages of the Alagoas coastal sediments we have therefore to depend 

 entirely upon the few fossils that have been found in the state and upon 

 such inferences as may reasonably be drawn from the geology of Sergipe, 

 just across the Rio Sao Francisco. 



Fig. 4. Cliaracterisitic view looking southward along the coast, nineteen 

 kilometers north of Jequia da Praia. (Crandall phot.) 



In the state of Alagoas the coastal sedimentary belt varies in width 

 from about ten kilometers in the north to sixty kilometers in the vicinity 

 of Penedo on the south. These sediments formerly extended further 

 inland and also further toward the east, but they have been removed by 

 denudation on the north and west, and have been encroached upon by the 

 ocean on the east until only this narrow belt now remains. The encroach- 

 ment of the sea has left a great deal of the coast in the form of bare and 

 abrupt escarpments some fifty to ninety meters high. The illustrations 

 incorporated in the text (Figs. 1-6) are made from photographs taken in 



