moodworth: geological expedition to brazil and chile. Ill 



fragments seems to point to some shifting of the residual clays. The 

 definite termination of the band of quartz fragments at a distance of a 

 few yards from the outcrop of the vein means that this old surface 

 was at the beginning of the period of weathering swept clean of quartz 

 fragments, either because of a steeper slope than that now found at 

 the locality or by reason of a more powerful run off. This latter 

 possibility is consonant with the hypothesis of a heavier rainfall 

 during the Pleistocene, however much the above attempt to calculate 

 the time employed may vary from the true duration of Post-Tertiary 

 epoch. 



River Terraces. — Along several of the larger rivers of south Brazil 

 there are terraces of sand and gravel evidently remnants of a former 

 aggraded floor of their valleys. These deposits date back presumably 

 to the Pleistocene with its greater rainfall. 



For examples, a terrace occurs in the Rio Iguassu between kilometer 

 posts 47 and 48 along the railway between Araucaria and Balsa nova 

 Stations in Parana; a terrace also occurs north of Balsa nova at km. 

 post 59. Other fragments of this terrace occur along the river 

 further up the valley. 



The Rio Capivary in Parana between Lago and Palmeira exhibits 

 a terraced plain. 



In southern Sao Paulo a gravel terrace of old river cherts is crossed 

 by the railway between Herval Station and Engenheiro Hermilho 

 Station. 



These gravelly terraces, apparently of the same epoch as the 

 Tamandua gravels on the hillsides, are probably in their later stages 

 derived from the washing down and gullying of these deposits. 

 Owing to the nature of river changes it is improbable that the forma- 

 tion of the terraces by reexcavation of the old valley floors should 

 have been s^'nchronous throughout the area under discussion. 



Numerous cuttings along the railway's in Sao Paulo and Parana 

 show that the claye}' deposits there, varying but little from the terra 

 roxa and the terra vermehlo, are not strictly residual but are rather 

 transported or shifted, however much they have deca^'ed in their 

 present sites. Dr. Derby expressed the opinion that the red earth, 

 of which an excellent exposure was examined at the railway station in 

 Sao Pedro de Itarare on the confines of Sao Paulo and Parana, was 

 an equivalent of the loess of other regions. 



The thickness of these deposits varies greatly. Many sections 

 were seen varying from six to ten feet, but in many the bottom was 

 not exposed. The material appears to be developed particularly 



