44 bulletin: museum of comparative zoology. 



north and south of the present Hne 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 unfossihferous 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 





Fig. S. — Sandstone escarpment looldng northeast from Lago, Parand. 



of the outcrop of shales is however such as to indicate that they 

 originall}^ 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 anrl 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 



