any: gee 
No fossils appear to have been preserved from the boring, but 
the amount of grvenish sand found would indicate that the lower 
half of the beds probably belong to Cretaceous sediments, especially 
the portion below 71 meters in depth, hence the beginning of the 
subsidence which has depressed the southern coast of Brazil, and 
carried the elevated gneiss and granite areas which rise so sharply 
along the coast between Rio de Janeiro and Florianopolis, to a lower 
level, problably dates from pre-Cretaceous times and may he connected 
with those great orogenic movements that piled up the immense 
flows of eruptives, dikes, and laccolites over the region of the Serra 
Geral which took place subsequent to the close of the Triassic period. 
This depression is probably the one which sunk the « Gondwana 
Land» of the British geologists, thus destroying the former land 
connection of Africa with South America which permitted the passage 
of the plants and animals freely from one region to the other, as 
shown by the identity of the fossil remains in the rocks of South 
Brazil, South Africa and India. 
The great’ outflows of basaltic rocks which heralded the close 
of Triassic time have, of cowr'se, profoundly modified the physical 
geography of Brazil, probably changing the course of many of 
its pre-Triassic rivers, and causing that wonderful system of rapids, 
cascades, and vertical falls which interrupt all the rivers of South 
Brazil, rendering interior navigation difficult, and frequently im- 
possible for any considerable distance away from the sea coast. 
Hence, practically all of the rivers and smaller streams rising 
within the area mentioned, simply tumble down in cascades and 
rapids to within a few miles of the sea where no dikes of eruptive 
rocks are present to interrupt their courses, as between Blumenau 
and Itajahy, or perchance where the same may nave been carried 
down and oblitered by the apparent subsidence or drowning of the 
coast line referred to above. 
The great catavacts, like the «Seven alls» (Sete Quedas ) of 
the Paranda, and the numerous falls and rapids of the Uruguay and 
other rivers within the zone of the Carboniferous and Triassic 
formations, are practically all caused }y) these dikes and sills of 
eruptive rocks. Thus, while these and other igneous agencies have 
given rise to conditions which forbid a large inland commerce on 
the rivers of South Brazil, they haveat the same time provided such 
great resources for thecheap generation of electric power, as to com- 
