n the Solimoens and
Maranon it is a stiff loam or vegetable mould, in many places twenty
feet deep.

Both in botany and zoology, South America is a natural and
strongly-marked division, quite as distinct from North America as from
the Old World; and as there are no transverse barriers, there is a
remarkable unity in the character of the vegetation. No spot on the
globe contains so much vegetable matter as the Valley of the Amazon.
From the grassy steppes of Venezuela to the treeless Pampas of Buenos
Ayres, expands a sea of verdure, in which we may draw a circle of eleven
hundred miles in diameter, which shall include an ever green, unbroken
forest. There is a most bewildering diversity of grand and beautiful
trees--a wild, unconquered race of vegetable giants, draped, festooned,
corded, matted, and ribboned with climbing and creeping plants, woody
and succulent, in endless variety. The exuberance of nature displayed in
these million square acres of tangled, impenetrable forest offers a bar
to civilization nearly as great as its sterility in the African deserts.
A _macheta_ is a necessary predecessor: the moment you land (and it is
often difficult to get a footing on the bank), you are confronted by a
wall of vegetation. Lithe lianas, starred with flowers, coil up the
stately trees, and then hang down like strung jewels; they can be
counted only by myriads, yet they are mere superfluities. The dense dome
of green overhead is supported by crowded columns, often branchless for
eighty feet. The reckless competition among both small and great adds to
the solemnity and gloom of a tropical forest. Individual struggles with
individual, and species with species, to monopolize the air, light, and
soil. In the effort to spread their roots, some of the weaker sort,
unable to find a footing, climb a powerful neighbor, and let their roots
dangle in the air; while many a full-grown tree has been lifted up, as
it were, in the strife, and now stands on the ends of its stilt-like
roots, so that a man may walk upright between the roots and under the
trunk.[167]

[Footnote 167: Buttress roots are not peculiar to any one species, but
common to most of the large trees in the crowded forest, where the
lateral growth of the roots is made difficult by the multitude of
rivals. The Paxiuba, or big-bellied palm, is a fine example.]

The mass of the forest on the banks of the great river is composed of
palms (about thirty species[168]), legumino