28 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
and the top of them, at a few places only, rises perhaps as much as a 
metre above high tide. Sand dunes lie on top of these beds, and behind 
the dunes the water soaks down, passes through the dunes, and following 
along the top of the rocks issues as amber-colored springs on the beach. 
At one place a large spring has cut through the rock and comes out 
two metres or more below its surface. Not a trace of a fossil could be 
Гіс. 6. Theoretic section showing the relations of the Bahia Formosa beds 
to the Cunhahu sandstone. 
found in a kilometre of exposure of this rock. The beds are horizontal, 
but they do not appear in the Bahia Formosa section of the, colored beds 
which are cut clear down to the water’s edge. The snuff-colored beds 
must, therefore, rest unconformably against the valley originally cut by 
the Cunhahú in these sediments. | 
A few kilometres north of the Cunhahá and north of Rio Sibaúma, the 
bluffs have lying against them at one place horizontally bedded sedi- 
ments made of fragments derived 
from these bluffs themselves. 
'These beds contain no fossils, 
and from the appearance of the 
materials it is supposed that the 
newer beds here were deposited 
since the discoloration of the 
bluffs. At this place the top 
of the deposit is barely within 
reach of the highest spring tides. 
Таш not at all sure that these 
newer beds are related to the 
Fra. 7. Section through Ше bluff and snuff-colored ones. 
beach north of Rio Sibatima. At the mouth of Rio Maman- 
guape, S. lat. 6° 46’, on the point 
of land just east of the Barra de Mamanguape are exposed very dark 
sandstones, of about the same texture as the reef rocks and containing 
quartz, but in color from dark brown to perfectly black. Between the 
