1885.] Physical Geography of the Amazons Valley. 31 
only to those portions which are above water during more than 
half the year; lower and perennially wet tracts are known as 
ygapos In contradistinction, all dry land which is out of reach 
of the annual floods is called zerre-firme. Islands of high land 
(ilhas de terra-firme) are frequently seen in the midst of the var- 
zeas and along the irregular borders of the flood-plain it often 
happens that the varzea and terre-firme are mingled in the most 
complicated manner; such places would be puzzling enough to 
the student were it not that the alluvial land can be at once dis- 
tinguished by its vegetation. Frequently the varzea or ygapo 
forest is continuous with that of the /erre-firme, but the trees are 
always of distinct species, and no experienced woodsman would 
think of confounding them. 
On the southern side of the mouth of the Amazons, separating 
it from the Tocantins and Para, is a great lozenge-shaped island 
cailed Marajó. At its south-western end it is separated from the 
mainland by a network of narrow channels connecting the Ama- 
zons with the Tocantins. The tides ebb and flow in these chan- 
nels but the south-westerly current predominates, so that a por- 
tion of Amazonian water reaches the Tocantins. The channels 
are cut through a wide stretch of alluvial land which is directly 
continuous with the flood-plain of the Amazons. Marajo itself is 
almost entirely composed of or covered with alluvial deposits. 
The eastern and northern parts of the island are occupied by 
varzea meadows, while the southern and western portions are 
almost continuous swamps, noted for their rubber trees and for 
their deadly fevers. The whole island abounds in shallow lakes, 
and it is cut up by hundreds of small creeks and channels, the 
haunts of alligators and serpents. Only along the eastern and 
southern edges there are some narrow strips of ¢erre-firme, true 
rocky land raised well above the highest floods. The first settlers 
took advantage of these little dry spots, building their houses on 
- them and sheltering their cattle there when the meadows were 
overflowed. Breves and other villages owe their situations to 
these zorroes. 7 
From the highlands of Guiana a number of rivers flow down, 
with many rapids and falls, to the Amazons. None of these 
streams have been explored to their sources, and most of them 
are known only near their mouths, where they flow across the 
1In Tupy, a wet land or swamp. 
