woodworth: geological exp"editiox to brazil and chile. 103 



corresponding there geologically to the Serra do Mar, and which has 

 its watershed in the lofty crest of the Triassic escarpment on the 

 west of the Permian belt of coal-bearing shales.^ The Ypiranga, an 

 affluent of the Bay of Paranagua, is apparently in the act of tapping 

 the westward sloping surface of the planalto back of the Serra 

 do INIar. 



According to Drs. Derby and Euzebio P. de Oliveira the Permian 

 sandstone overlaps the Devonian shales at places in Parana and rises 

 towards the crest of the Serra as at Vilha Vehla, a point of deeply 

 disintegrated rocks southeast of Ponta Grossa, the name Vilha Vehla 

 being applied in the same sense that "Rock City" is employed in 

 North America. This ridge dies out northward in Sao Paulo and 

 southwards in Parana so that in Santa Catharina the geologically 

 higher escarpment of the trap plateau on the south comes in as the 

 first range inside the coastal mountain belt. 



The relatively even sky-line of the Devonian cuesta forms a strik- 

 ing feature in the treeless landscapes for many miles in Parana. 

 The summit attains elevations exceeding 3,000 feet and approaches 

 the level of the hypothetical Cretaceous peneplain out of the nearly 

 level surface of which the lowlands between the ridges and plateaus 

 of the planalto have been sculptured by Tertiary and more recent 

 erosion. In northern Parana and southern Sao Paulo the topographic 

 relief becomes complicated by the erosion of longitudinal valleys and 

 by the association of ridges developed on the lower Permian sandstones 

 which succeed on the west of the Devonian outcrop. The streams in 

 this district also have cut deep gorges across these ridges apparently 

 along lines of drainage inherited from the time Avhen they flowed on 

 the Cretaceous peneplain. Such appears to be the origin of the 

 defile in the massive sandstones through which the Yapo flows in 

 the country northwest from Castro to Tibagy. At Joachim Murinho 

 Station the railway follows a broad gap in the sandstones which 

 appears to have been once occupied by a river much larger than the 

 present stream. The escarpment of the Devonian here becomes 

 very irregular by reason of dissection. The steep sandstone cliffs 

 form precipices overlooldng lowlands excavated to the level of the 

 crystalline rock-floor as at Pirahy. A characteristic view is to be had 

 from Fabio Rego Station looking towards the clift's of the Serra 

 Morumgaba surmounted by the Morro do Chapeo. 



' For some account of the Ribeira de Iguape with maps and plans see a report 

 entitled Exploracao do Rio Ribeira de Iguape. Comm. Geog. e Geol. de S. Paulo, 

 1908. 



