WOODWORTH: GEOLOGICAL EXPEDITION TO BRAZIL AND CHILE. 97 
higher sheet. From these observations it is to be inferred that 
fracturing of the underlying sandstones and the migration of the basic 
magmas towards the surface went on during the period of great 
trappean outbreaks presumably with a foundering of a vast area 
which became flooded with successive sheets of lava from many 
fissures. Between one and two kilometers south of the dike above 
described another but much narrower basic dike about a foot wide 
crosses the mule path near a small stream. An extended search would 
probably reveal many other dikes once serving as feeders to the over- 
lying trap sheets. 
The Lages Area.— For several leagues around Lages the trap sheets 
have been denuded leaving the Triassic sandstones and shales of the 
Sao Bento beds of Dr. I. C. White’s report at the surface apparently 
in an anticlinal dome. On the northern margin of this tract the trap 
overlooks it with a well-defined, but much notched, escarpment rising 
a few hundred feet above the general level. At the eastern limit of 
vision from the Lages road, a conical outlier of the trap forms a 
prominent hill, showing that along this line, as on the face of the escarp- 
ment overlooking the Permian territory, erosion and not faulting has 
produced the trap escarpment. 
The Lake Basins of Santa Catharina— “La province de Santa 
Catharina est couverte de petits lacs.” (Malte-Brun. Geographie 
1857, 6, p. 687.) In the interstream areas of the trap surface large 
tracts frequently depart widely in their slopes from the sculptured 
forms produced by running water. The surface becomes undulating 
with saucer-shaped pits always opening out on one side towards the 
drainage way of the district. As the small basins become deeper and 
more numerous, inosculating rounded ridges rise between them, giv- 
ing such tracts the appearance of New England kame-kettles and their 
winding kame-ridges. In the pits there are shallow lakes or pools. 
These depressions and ridges are evidently the work of long continued 
secular weathering of the basalt combined with the removal of the 
products of disintegration and decomposition. 
Most of these basins were at the time of my visit more or less 
occupied by standing water, some of them forming shallow lakelets 
in which grew a brilliant green grass. Other basins presented the 
appearance of level meadows from the filling of presumably residual 
clay and vegetable matter which they contained. At Sao Joao on the 
trap plateau south of Porto da Unido, a pit some three or four feet 
in depth had been dug in one of these floored depressions, showing 
beneath a few inches of vegetable matter a light colored clay evi- 
dently the product of decomposition of the trap rock. 
