the Rio Colorado; and it appears that the same kind of country extends
inland from this river, in a sweeping line as far as San Luis and
perhaps even further north. To the eastward of this curved line lies
the basin of the comparatively damp and green plains of Buenos Ayres.
The sterile plains of Mendoza and Patagonia consist of a bed of
shingle, worn smooth and accumulated by the waves of the sea while the
Pampas, covered by thistles, clover, and grass, have been formed by the
ancient estuary mud of the Plata.
After our two days' tedious journey, it was refreshing to see in the
distance the rows of poplars and willows growing round the village and
river of Luxan. Shortly before we arrived at this place, we observed
to the south a ragged cloud of dark reddish-brown colour. At first we
thought that it was smoke from some great fire on the plains; but we
soon found that it was a swarm of locusts. They were flying northward;
and with the aid of a light breeze, they overtook us at a rate of ten
or fifteen miles an hour. The main body filled the air from a height
of twenty feet, to that, as it appeared, of two or three thousand above
the ground; "and the sound of their wings was as the sound of chariots
of many horses running to battle:" or rather, I should say, like a
strong breeze passing through the rigging of a ship. The sky, seen
through the advanced guard, appeared like a mezzotinto engraving, but
the main body was impervious to sight; they were not, however, so thick
together, but that they could escape a stick waved backwards and
forwards. When they alighted, they were more numerous than the leaves
in the field, and the surface became reddish instead of being green:
the swarm having once alighted, the individuals flew from side to side
in all directions. Locusts are not an uncommon pest in this country:
already during the season, several smaller swarms had come up from the
south, where, as apparently in all other parts of the world, they are
bred in the deserts. The poor cottagers in vain attempted by lighting
fires, by shouts, and by waving branches to avert the attack. This
species of locust closely resembles, and perhaps is identical with, the
famous Gryllus migratorius of the East.
We crossed the Luxan, which is a river of considerable size, though its
course towards the sea-coast is very imperfectly known: it is even
doubtful whether, in passing over the plains, it is not evaporated and
lost. We slept in the village of Luxan, which is a small place
surrounded by gardens, and forms the most southern cultivated district
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