OF THE SKRGIPE-ALAGOAS BASIX OF BRAZIL. 373 



and du not, of themselves, throw much light upon the changes through which the 

 coast has passed. Xowhere along the Biazilian coast from the frontier of Uruguay 

 to Cape North are any fossiliferous paleozoic beds exposed, and there are but few 

 places in which a section from the ocean to the archa\in rocks would pass llirough 

 anything more than recent deposits and the horizontal tertiary beds referred to above. 

 Til no place along the wliole coast, however, can a wider and deeper section 

 be fouml, or one in which the rocks aftbrd a more complete history of the 

 changes through which this part of the continent has passed from paleozoic times 

 up to the present than the basin cut by the Kios 8ao Francisco and Sergiiie, and 

 which lies within the two provinces of Sergipe and AlagOas. The importance of this 

 region is due to 



1. The representation of a geologic range unusual in Brazil. 



2. The rich fossiliferous nature of many of the beds. 



3. The accessibility of good exposure across the entire section. 



Doubtless one of the chief reasons that these two provinces are not better known 

 geologically, is the fact that they are not on the principal line of travel between Eu- 

 roi)e and South America, and are, therefore, more or less inaccessible, and if the geo- 

 logical importance of the region has not been recognized, it must be attributed to the 

 fact that hitherto nothing, or next to nothing, has been known of it. 



With the exception of a canoe voyage by Gardner along the Rio Sao Francisco 

 to Piranhas in 1837, and a very brief visit to Maroim by Prof. Hartt in the year 

 I860, none of the writers upon the geology of Brazil, prior to the work done by the 

 Imperial Geological Sui'vcy, ever visited the Sergipe- Alagoas region, and even those 

 few earlier writers have but little to say of the geology of this section of the country. 



I am of the opinion tlial the kcv to future successful ofcoloofic work in Brazil 

 lies in the careful study and comprehension of some such typical region as that com- 

 prised in the [)rovinces of Sergipe and Alagoas. The Bahia basin is an interesting 

 one, and, as Dr. White has pointed out in his recentl}' published "Contributions to 

 the Paleontology of Brazil," faunally more interesting perhaps than that of Sergipe- 

 Alagoas, but the Bahia basin being of lacustrine origin is sui f/eneris, as far as the 

 raesozoic geology of Brazil is understood.* The Sergipe- Alagoas beds on the other 

 hand are marine, the rocks above the archrean vary lithologically ami faunally, and 

 arc more or less exposed across the whole width of the region from the ocean to tlu-ir 

 inland margins at the base of the Serra d'ltabaiana, while at this lattci- locality, the 

 lowest of the sedimentary beds are well exposed whcic the seria is cut through 



• PIssis, in his memoir publislied l)y llie Frcncli Academy, p. 402, says llial llio tertiary beds of Uic interior of 

 Bra7.ii, and lying between Uic coast range and llio Serrn de Jfantiqueira, arc lacustrine. 



