but is richly provided with
mineral deposits. It breaks down less abruptly toward the Atlantic,
the slopes in Bahia being long and gradual. The Parnahyba _chapadao_
covers the state of Piauhy, the southern part of Maranhao, and the
western part of Ceara. Its general elevation is less than that of the
Sao Francisco region, owing to the slope of the plateau surface toward
the Amazon depression and to denudation. It resembles the Sao
Francisco region in its uncertain rainfall and exposure to droughts,
and in having large areas of _campos_ suitable for grazing purposes.
It is thinly wooded, except in the north, where the climatic
conditions approach those of the Amazon valley. Its climate is more
tropical and its development has gone forward less rapidly than in the
more temperate regions of the south. The Amazonian _chapadao_, which
includes the remainder of the great Brazilian plateau west of the Sao
Francisco and Parnahyba regions and which appears to be the
continuation of these tablelands westward, is much the largest of
these plateau divisions. It covers the greater part of the states of
Matto Grosso and Goyaz, a large part of southern Para, the southern
margin of Amazonas, and a considerable part of western Maranhao. It
includes the river basins of the Tocantins-Araguaya, Xingu, Tapajos,
and the eastern tributaries of the Guapore-Madeira. A considerable
part of it has been excavated by these rivers to a level which gives
their valleys the elevation and character of lowlands, though isolated
hills and ranges with the characteristic overlying horizontal
sandstone strata of the ancient plateau show that it was once a
highland region. The southern margin of this plateau breaks down
abruptly toward the south and overlooks the Parana and Paraguay basins
from elevations of 2600 to 3000 ft. There is great diversity in the
character and appearance of this extensive region. It lies wholly
within the tropics, though its more elevated districts enjoy a
temperate climate. Its _chapadas_ are covered with extensive _campos_,
its shallow valleys with open woodlands, and its deeper valleys with
heavy forests. The rainfall is good, but not heavy. The general slope
is toward the Amazon, and its rivers debouch upon the Amazonian plain
through a succession of falls and rapids.

There remains only the elevated valley of the Parahyba do Sul, lying
between the so-calle