SEDIMENTARY BELT OF THE COAST OF BRAZIL = 235 
a thickness of at least 200 meters (and probably considerable more) 
of strata that, thus far, have not afforded fossils, except unrecogniz- 
able fragments of carbonized wood in their lower part, so that there 
is no paleontological evidence as to where the division line should 
be drawn. At about 50 meters below the leaf-bed there is a change 
in the character of the rock, marked by a water horizon, which appar- 
ently indicates a break in the succession; but what its significance 
may be has not been determined. ‘The beds below this horizon are 
somewhat more argillaceous than those above, and are more wide- 
spread, so that there is here an indication of unconformability by 
overlap. They are also more widespread than the beds below them 
that can be definitely assigned to the Cretaceous, but they are so like 
the upper arenaceous members of the latter series as to be inseparable 
from them without more study than has yet been given to the subject. 
These intermediate beds of the Bahia section may be presumed to 
represent the greater part of the so-called Tertiary of the costal 
region, and while there is a reasonable presumption that they will 
prove to belong to the early or middle parts of that age, it cannot 
be definitely proven that they are not upper Cretaceous. 
6. The outlines, so far as they have been determined, of the various 
fossiliferous deposits of the costal region, and the character of their 
rocks and fossils, indicate that they were formed in estuaries, or 
partially closed litoral basins, in which marine, brackish, and fresh- 
water sediments might be laid down simultaneously in different parts; 
or alternately. in the same parts. In view of this circumstance, 
much detailed study will be required to make out the details of the 
true succession of the different beds and their respective faunas.. In 
the light of our present knowledge, the apparent succession is as 
follows, in ascending order: 
a) A marine group, represented in Sergipe and at Marahu, well 
characterized by a Cretaceous molluscan fauna which in part shows 
Jurassic affinities. 
b) An estuarine group, represented about Bahia (including Mar- 
ahti), Ilheos, and the oil-shale localities of Alagoas, with a well- 
characterized Cretaceous vertebrate fauna, which also in part shows 
Jurassic affinities, land plants and reptiles, cyprids, and rarely fresh- 
water mollusks. 
