— a7 — 
than the overlying eruptives. Whether or not the Carboniferous beds 
underlie the seaal Torreson below the Rio do Rasto red beds, or 
Whether the latter have here trangressed eastward and rest upon 
the granite, nothing but the drill can decid. 
The thickness of the Sé0 Bento sandstone series is not less than 
200 meters on the Estrada Nova in Santa Catharina, and it possibly 
attains to 300 meters on rio Sao Bento where these beds are finely 
exposed along the highway which follows that iver and leads lo the 
high plateau of the Serra Geral. 
The top of the sandstone series is reached on rio Sao Bento at 
about 650-700 meters, and above this for 600 meters more succeed 
the great sheels of diabase up lo the summils of the mountain at 
1350 melers above the sea. 
The Serra Geral Eruptives 
Following the deposition of the S. Bento sandstones just described 
and at probably no distant subsequent date, there succeeded an epoch. 
of great volcanic activity over alarge portion of the area covered )y 
these highest of the Triassic sedimentary deposits. Great flows of 
diabasic and Jusallic lavas welled up through fissures and spread 
out in vast sheets one above the other along the region of the Serra 
Geral often submerging Lhe Siio Bento sandstones with GOO meters or 
more of eruptives. Sometimes these dikes lake a nearly vertical dire- 
ction, and pass tlvough all of the overlying strata, while again they 
cut diagonally across the beds at all angles, and frequently pass hori- 
zontally between the strata often branching and completely enclosing 
large masses of Lhe sendimentaries. 
dossibly many of these flows were laccolitic in their nature, and 
have been exposed by later erosion. 
The famous coffee lands of Sao Paulo with their deep red or 
“terra roxa’’ soils are formed from the decomposition of these eru- 
ptives which furnish the proper proportion of alkalies for the vigorous 
growth of the coffee tree, and the perfection of the coffee bean. 
These eruptives are finaly exposed along the Estrada Nova in 
Santa Catharina which has been built al great expense from Minas 
up thealmost vertical face of the Serra Geral to afford access lo and 
from the pasture lands of the great plateau known as the Campos. 
55u0 28 
