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WOODWORTH: GEOLOGICAL EXPEDITION TO BRAZIL AND CHILE. 111 
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 Iguassii 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 Parané 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 
Tamanduaé 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 synchronous throughout the area under discussion. 
Numerous cuttings along the railways in Sao Paulo and Parana 
show that the clayey 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 decayed 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 Itararé 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 appéars to be developed particularly 
