e Brazilian Guiana plateau, lying immediately north of
the equator, is in great part a hot, stony desert. Geographically it
belongs to the Amazon basin, as its western and southern slopes are
drained by tributaries of that great river. Climatically, however, it
is a region apart. It lies in the north-east trade winds belt, but the
mountain chain on its northern frontier robs these winds of their
moisture and leaves the greater part of the Brazilian plateau
rainless. Its eastern and western extremities, however, receive more
rain, the former being well forested, while the latter is covered with
grassy _campos_. South of the Amazon valley and filling a great part
of the eastern projection of the continent, is another arid,
semi-barren plateau, lying within the south-east trade winds belt, and
extending from Piauhy southward to southern Bahia. It covers the state
of Piauhy and the western or inland parts of the states of Ceara, Rio
Grande do Norte, Parahyba, Pernambuco and Bahia. The year is divided
into a dry and wet season, the first from June to December, when rain
rarely falls, the streams dry up and the _campos_ are burned bare, and
the second from January to May when the rains are sometimes heavy and
the _campos_ are covered with luxuriant verdure. The rains are neither
regular nor certain, however, and sometimes fail for a succession of
years, causing destructive _seccas_ (droughts). The interior districts
of Ceara, Pernambuco and Bahia have suffered severely from these
_seccas_. The sun temperature is high on these barren tablelands, but
the nights are cool and refreshing. The prevailing winds are the
south-east trades, which have lost some of their moisture in rising
from the coastal plain. In summer, becoming warmed by the heated
surface of the plateau, they sweep across it without a cloud or drop
of rain. In winter the plateau is less heated, and cold currents of
air from the west and south-west cause precipitation over a part if
not all of this region. South and south-west of this arid plateau lie
the inhabited tablelands of Rio de Janeiro, Sao Paulo and Minas
Geraes, where the climate is greatly modified by a luxuriant
vegetation and southerly winds, as well as by the elevation. Minas
Geraes is forested along its water courses and along its southern
border only; its sun temperature, therefore, is high and the rainfall
in its northern districts