If At The Present Time Two Or
Three Showers Of Rain Were To Fall Annually, Instead Of One,
As Now
Is the case during as many years, a small rill of water
would probably be formed in this great valley;
And then, by
irrigation (which was formerly so well understood by the
Indians), the soil would easily be rendered sufficiently
productive to support a few families.
I have convincing proofs that this part of the continent of
South America has been elevated near the coast at least from
400 to 500, and in some parts from 1000 to 1300 feet, since
the epoch of existing shells; and further inland the rise
possibly may have been greater. As the peculiarly arid character
of the climate is evidently a consequence of the height of the
Cordillera, we may feel almost sure that before the later
elevations, the atmosphere could not have been so completely
drained of its moisture as it now is; and as the rise has been
gradual, so would have been the change in climate. On this
notion of a change of climate since the buildings were
inhabited, the ruins must be of extreme antiquity, but I do
not think their preservation under the Chilian climate any
great difficulty. We must also admit on this notion (and
this perhaps is a greater difficulty) that man has inhabited
South America for an immensely long period, inasmuch as
any change of climate effected by the elevation of the land
must have been extremely gradual. At Valparaiso, within
the last 220 years, the rise has been somewhat less than 19
feet: at Lima a sea-beach has certainly been upheaved from
80 to 90 feet, within the Indo-human period: but such small
elevations could have had little power in deflecting the
moisture-bringing atmospheric currents. Dr. Lund, however,
found human skeletons in the caves of Brazil, the appearance
of which induced him to believe that the Indian race has
existed during a vast lapse of time in South America.
When at Lima, I conversed on these subjects [3] with Mr.
Gill, a civil engineer, who had seen much of the interior
country. He told me that a conjecture of a change of climate
had sometimes crossed his mind; but that he thought
that the greater portion of land, now incapable of cultivation,
but covered with Indian ruins, had been reduced to this state
by the water-conduits, which the Indians formerly constructed
on so wonderful a scale, having been injured by
neglect and by subterranean movements. I may here mention,
that the Peruvians actually carried their irrigating
streams in tunnels through hills of solid rock. Mr. Gill told
me, he had been employed professionally to examine one:
he found the passage low, narrow, crooked, and not of uniform
breadth, but of very considerable length. Is it not
most wonderful that men should have attempted such operations,
without the use of iron or gunpowder? Mr. Gill also
mentioned to me a most interesting, and, as far as I am
aware, quite unparalleled case, of a subterranean disturbance
having changed the drainage of a country. Travelling from
Casma to Huaraz (not very far distant from Lima), he
found a plain covered with ruins and marks of ancient
cultivation but now quite barren. Near it was the dry course of
a considerable river, whence the water for irrigation had
formerly been conducted. There was nothing in the appearance
of the water-course to indicate that the river had not flowed
there a few years previously; in some parts, beds of sand and
gravel were spread out; in others, the solid rock had been
worn into a broad channel, which in one spot was about 40
yards in breadth and 8 feet deep. It is self-evident that a
person following up the course of a stream, will always
ascend at a greater or less inclination: Mr. Gill, therefore,
was much astonished, when walking up the bed of this
ancient river, to find himself suddenly going down hill. He
imagined that the downward slope had a fall of about 40 or
50 feet perpendicular. We here have unequivocal evidence
that a ridge had been uplifted right across the old bed of a
stream. From the moment the river-course was thus arched,
the water must necessarily have been thrown back, and a new
channel formed. From that moment, also, the neighbouring
plain must have lost its fertilizing stream, and become a
desert.
June 27th. - We set out early in the morning, and by midday
reached the ravine of Paypote, where there is a tiny rill
of water, with a little vegetation, and even a few algarroba
trees, a kind of mimosa. From having firewood, a smelting-
furnace had formerly been built here: we found a solitary
man in charge of it, whose sole employment was hunting
guanacos. At night it froze sharply; but having plenty of
wood for our fire, we kept ourselves warm.
28th. - We continued gradually ascending, and the valley
now changed into a ravine. During the day we saw several
guanacos, and the track of the closely-allied species, the
Vicuna: this latter animal is pre-eminently alpine in its
habits; it seldom descends much below the limit of perpetual
snow, and therefore haunts even a more lofty and sterile
situation than the guanaco. The only other animal which we
saw in any number was a small fox: I suppose this animal
preys on the mice and other small rodents, which, as long as
there is the least vegetation, subsist in considerable numbers
in very desert places. In Patagonia, even on the borders of
the salinas, where a drop of fresh water can never be found,
excepting dew, these little animals swarm. Next to lizards,
mice appear to be able to support existence on the smallest
and driest portions of the earth - even on islets in the midst
of great oceans.
The scene on all sides showed desolation, brightened and
made palpable by a clear, unclouded sky.
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