44 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
north and south of the present line of outcrop where the Permian 
rests upon the Pre-Devonian terrane is evidently due to erosion 
of the beds in Upper Devonian or Carboniferous times. 
That the unfossiliferous sandstones referred to the Lower Devonian 
represent the shoreward facies of marine sediments is clear and it is 
possible that the upper part of the beds may represent shore deposits 
laid down simultaneously with the lower off-shore portion of the 
fossiliferous shales known to be of Mid-Devonian age. The thickness 
a ae / 
— ~ 6% | ee SS ree Se Go ETT 
oN tee SEP / Tot toe Saxe 
SS ETL ( Lote PES 
Ct 
Fic. 8.— Sandstone escarpment looking northeast from Lago, Parana. 
of the outcrop of shales is however such as to indicate that they 
originally extended much to the eastward of the present underlying 
eastern limit of the sandstone just as the peneplaned surface on which 
the terrane rests evidently extended to the eastward of its existing 
traces. 
The inference above stated that the Devonian shore in this region 
lay to the eastward is not only suggested by the westward existing 
dip of the beds, which attitude might be explained by a rotational tilt 
from an original eastward dip, but the assumption is in consonance 
with the basin-like form of the entire geological province of south 
Brazil. In Triassic times over a vast area non-marine sediments were 
poured on to this tract from outlying areas of land. In the preceding 
Permian both marine and non-marine sediments accumulated in the 
same or nearly the same area; and on the eastern border of the outcrop 
of these sediments, as will be shown later, there is evidence of the 
derivation of materials from an area of erosion on the east. The 
Carboniferous period was here one evidently of uplift or withdrawal 
of the sea and erosion under the atmosphere, a fact of little import 
on the attitude of the Devonian stratigraphic plane other than to 
indicate the probable proximity of land in this region in the later 
Devonian. 
The Permian Terrane.— It now seems most likely that the strata. 
referred to the Carboniferous in the earlier reports on this district are 
of Permian age. The fossil plants and few reptilian remains found 
