CHAPTER, IIL 
The Carboniferous and Triassic Rocks. 
Resting unconformably upon the Devonian shales, or older beds 
when the Devonian is absent, and sometimes upon the granite itself, 
we generally find a very coarse conglomerate, or often simply a 
great bed of large boulders some of which may be 2 to3 meters in 
diameter, and this boulder bed appears to mark the beginning of 
Carboniferous time in South Brazil. From these oldest and lowest 
beds of the Carboniferous there appears to bea regular succession of 
rocks, unbroken by any great unconformity, up through the coal 
bearing series to the top of the red and gray Triassic sandstones 
and conglomerates which form massive cliffs and lofty escarpments 
high up the eastern face of the Serra Geral. 
Resting upon these highest sandstones, and often thrust between 
the massive strata, there comes a series of old eruptives of basaltic, 
or diabasic character which form the general surface of the [Campos 
and the higher peaks of the Serra Geral. These volcanic rocks are 
well exposed in Santa Catharina along the Estrada do Rio do Rasto 
(Estrada Nova), a mountain highway constructed at great cost up 
the almost perpendicular face of these old eruptives where they over- 
lie the highest sandstones of the Trias, in great sheets of diabase and 
basalt, much of it amygdaloidal, and extend upward with a thickness 
of 600 meters to the summit peaks of the mountain at an elevation 
of more than 1400 meters above the sea. 
The following section of the rocks exposed along the Estrada Nova 
in Santa Catharina is based upon measurements made under the 
supervision of Dr. Esdras do Prado Seixas, Engineer for the Coal 
Commission, during the year 1904, and a portion of 1905, who rana 
line of levels along the Estrada Nova from. Minas to the contact of 
the diabase with the topmost sandstone of the Trias exposed, near 
Morro Pellado 19 1/2 kilometers westward from Minas, and under 
whose supervision also was made the map of the Minas region pub- 
lished with this report. 
