nce of the coast
are apt to mistake their way, when they encounter these sand-hills.

The medanos with immovable bases are formed on the blocks of rock which
are scattered about the plain. The sand is driven against them by the
wind, and as soon as it reaches the top point it descends on the other
side until that is likewise covered; thus gradually arises a
conical-formed hill. Entire hillock-chain with acute crests are formed
in a similar manner. The small hillock-chain, by which the coast is
intersected obliquely from east to west, is a boundary which arrests the
progress of the wandering medanos; otherwise fruitful oases would soon
be converted into barren sand-flats. A correct observation of these
hillock-chains affords a most certain scale for ascertaining the
direction of the prevailing wind. On their southern declivities are
found vast masses of sand drifted thither by the mid-day gales. The
northern declivity, though not steeper than the southern, is only
sparingly covered with sand. If a hillock-chain somewhat distant from
the sea extends in a line parallel with the Andes, namely from S.S.E. to
N.N.W., the western declivity is almost entirely free of sand, as it is
driven to the plain below by the southeast wind, which constantly
alternates with the wind from the south.

The movements and new formations in the deserts (like restorations
from death to life) are only in full activity during the hot season;
for then the parched sand yields to the slightest pressure of the
atmosphere. In the cold season its weight increases by the absorption
of humidity. The particles unite in masses, and more easily resist
the wind. In the meantime the hillocks also acquire more firmness or
compression by the increased weight which presses on them from above.

In November, summer commences. The rays of the sun are refracted on the
light grey sandy carpet, and are reflected back with scorching power.
Every living thing which does not quickly escape from their influence is
devoted to certain destruction. No plant takes root in the burning soil,
and no animal finds food on the arid lifeless surface. No bird, no
insect moves in the burning atmosphere. Only in the very loftiest
regions, the king of the air, the majestic condor, may be seen floating,
with daring wing, on his way to the sea coast. Only where the ocean and
the desert blend with each other is there life and movement. Flocks of
carrion crows swarm over the dead remains of