WOODWORTH: GEOLOGICAL EXPEDITION TO BRAZIL AND CHILE. 49 
border of the Triassic formation thus constituted is deeply notched by 
the greater rivers, such as the Iguassi. The escarpments lying like 
great loops on the eastern limits of the formation between these river 
valleys receive various names such as the Serra Geral, the Serra da 
Esperanga, etc. Siemiradzki in a section reproduced by Suess gives 
a somewhat different interpretation to the trap mass of the Serra da 
Esperan¢a, but the section of the same field credited to Derby is in 
harmony with the structure here described as is also the section 
traversed by the writer between Rio Negro and Lages in Santa 
Catharina. Further consideration of the Triassic rocks and their 
bearing on the climatic conditions succeeding the Permian glacial 
epoch are reserved for a following chapter. 
The Tertiary Deposits Whether or no the Cretaceous deposits 
covering the border of the continent south of the Amazon have 
representatives now in some of the sands and clays of the coastal 
border south of Rio de Janeiro, there are rather recondite reasons for 
believing that such deposits may once have flanked the coastal slope 
of the Serra do Mar province; if so they were not long after their 
deposition worn away. On the upland or planalto, to use the Brazilian 
name of the plateau region, no known deposits occur between the 
Trias and certain sediments in Sao Paulo which from their fossil 
fishes are shown to be of fresh-water origin and Tertiary in age. These 
deposits are most extensively developed in the valley of the Parahyba 
between the Serra da Mantiqueira and the Serra do Mar and in a 
smaller tract underlying the city of Sao Paulo. In these cases, the 
beds occupy not well understood depressions in the Pre-Devonian 
terrane. In what follows on the topography of the plateau, the 
occurrence of these non-marine deposits will be advanced as evidence 
of a change of attitude of the region in late Tertiary times. 
General Structure of the South Brazilian Permian Area. It remains to 
describe the general structure of the region embracing the states from 
Sao Paulo southward to Rio Grande do Sul. A glance at the geologi- 
cal sketch map, Plate 15, shows that this region has been warped 
in Post-Triassic times. A broad synclinal structure with its axis in an 
east and west direction occupies southern Santa Catharina and 
northern Rio Grande do Sul, causing the Permian and Triassic in turn 
to approach the Atlantic coast; and, because of the depression of the 
beds towards the synclinal axis, they attain sea-level and in the 
case of the Permian descend below that level. On the north of this 
structure a complementary anticlinal axis is less well defined in central 
eastern Parana. Its position is marked out by the arcuate trend of 
