1897.] Fossils and Fossilization. 17 
clay and detritus from the eroded mountain chains of Brazil. 
- And this is due to the fact, as pointed out by J. Ball (Notes of a 
Naturalist) that a continuous and heavy rainfall in Brazil not 
only aids in the process of disintegration of the rock, but sup- 
plies the necessary vehicle for transporting itaway. Theannual 
rainfall in Brazil varies from 100 to 130 inches, and as its east- 
ern seaboard is its oldest surface, this region has been “subjected 
throughout vast periods of geological time to the utmost force 
of disintegrating agencies, applied to a rock very liable to yield 
to them, and where, without reckoning the large proportion 
which must have been carried by rivers to the sea, we see such 
vast deposits of the disintegrated materials formed out of the 
same matrix.” The lofty maritime ranges of Brazil have been 
reduced by this constant withdrawal of their materials, and 
the predecessor of the present river system which had its in- 
ception in those early ages afforded the conduits by which the 
vast quantity of detrital matter was borne down over the broad 
pampas and plains of Argentina and Uruguay. We may 
conceive that this weathering and deposition were carried on 
with greater energy at a time when meteorological disturban- 
ces were more violent, and when these same streams, repre- 
sented in that distant time by much shorter rivers, had a 
steeper slope, ran more swiftly, and possessed greater erosive 
or tearing and sweeping power. This discharge of abraded 
matter has built up the wide level country which now consti- 
tutes the flat lands of Argentina and Uruguay, whose exten- 
sive pampas arose through this sedimentation continued 
through ages of this current of abrasion. In turn the rivers 
ploughing new channels through the vast accumulations over 
which they were now compelled to make their way, contin- 
ually added to the outskirts of the new formation, and with 
every increment extended their own banks, and gradually 
assumed their present proportions and their present course. 
For, to use the language of Prof. Ball, “it cannot be doubted 
that the finer constituents carried down by the Parana and its 
tributary, the Paraguay, from the same original home, have 
largely contributed to the formation of the Argentine pampas, 
and Paraguay, including the northern portion of the Gran- 
2 
