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height of 23 vertical feet above the highest spring-tides. Their
force must have been prodigious; for at the Fort a cannon with its
carriage, estimated at four tons in weight, was moved 15 feet
inwards. A schooner was left in the midst of the ruins, 200 yards
from the beach. The first wave was followed by two others, which in
their retreat carried away a vast wreck of floating objects. In one
part of the bay, a ship was pitched high and dry on shore, was
carried off, again driven on shore, and again carried off. In
another part two large vessels anchored near together were whirled
about, and their cables were thrice wound round each other: though
anchored at a depth of 36 feet, they were for some minutes aground.
The great wave must have travelled slowly, for the inhabitants of
Talcahuano had time to run up the hills behind the town; and some
sailors pulled out seaward, trusting successfully to their boat
riding securely over the swell, if they could reach it before it
broke. One old woman with a little boy, four or five years old, ran
into a boat, but there was nobody to row it out: the boat was
consequently dashed against an anchor and cut in twain; the old
woman was drowned, but the child was picked up some hours
afterwards clinging to the wreck. Pools of salt-water were still
standing amidst the ruins of the houses, and children, making boats
with old tables and chairs, appeared as happy as their parents were
miserable. It was, however, exceedingly interesting to observe, how
much more active and cheerful all appeared than could have been
expected. It was remarked with much truth, that from the
destruction being universal, no one individual was humbled more
than another, or could suspect his friends of coldness - that most
grievous result of the loss of wealth. Mr. Rouse, and a large party
whom he kindly took under his protection, lived for the first week
in a garden beneath some apple-trees. At first they were as merry
as if it had been a picnic; but soon afterwards heavy rain caused
much discomfort, for they were absolutely without shelter.

In Captain Fitz Roy's excellent account of the earthquake it is
said that two explosions, one like a column of smoke and another
like the blowing of a great whale, were seen in the bay. The water
also appeared everywhere to be boiling; and it "became black, and
exhaled a most disagreeable sulphureous smell." These latter
circumstances were observed in the Bay of Valparaiso during the
earthquake of 1822; they may, I think, be accounted for by the
disturbance of the mud at the bottom of the sea containing organic
matter in decay. In the Bay of Callao, during a calm day, I
noticed, that as the ship dragged her cable over the bottom, its
course was marked by a line of bubbles. The lower orders in
Talcahuano thought that the earthquake was caused by some old
Indian women, who two years ago, being offended, stopped the
volcano of Antuco. This silly belief is curious, because it shows
that experience has taught them to observe that there exists a
relation between the suppressed action of the volcanos, and the
trembling of the ground. It was necessary to apply the witchcraft
to the point where their perception of cause and effect failed; and
this was the closing of the volcanic vent. This belief is the more
singular in this particular instance because, according to Captain
Fitz Roy, there is reason to believe that Antuco was noways
affected.

The town of Concepcion was built in the usual Spanish fashion, with
all the streets running at right angles to each other; one set
ranging south-west by west, and the other set north-west by north.
The walls in the former direction certainly stood better than those
in the latter; the greater number of the masses of brickwork were
thrown down towards the north-east. Both these circumstances
perfectly agree with the general idea of the undulations having
come from the south-west; in which quarter subterranean noises were
also heard; for it is evident that the walls running south-west and
north-east which presented their ends to the point whence the
undulations came, would be much less likely to fall than those
walls which, running north-west and south-east, must in their whole
lengths have been at the same instant thrown out of the
perpendicular; for the undulations, coming from the south-west,
must have extended in north-west and south-east waves, as they
passed under the foundations. This may be illustrated by placing
books edgeways on a carpet, and then, after the manner suggested by
Michell, imitating the undulations of an earthquake: it will be
found that they fall with more or less readiness, according as
their direction more or less nearly coincides with the line of the
waves. The fissures in the ground generally, though not uniformly,
extended in a south-east and north-west direction, and therefore
corresponded to the lines of undulation or of principal flexure.
Bearing in mind all these circumstances, which so clearly point to
the south-west as the chief focus of disturbance, it is a very
interesting fact that the island of S. Maria, situated in that
quarter, was, during the general uplifting of the land, raised to
nearly three times the height of any other part of the coast.

The different resistance offered by the walls, according to their
direction, was well exemplified in the case of the Cathedral. The
side which fronted the north-east presented a grand pile of ruins,
in the midst of which door-cases and masses of timber stood up, as
if floating in a stream. Some of the angular blocks of brickwork
were of great dimensions; and they were rolled to a distance on the
level plaza, like fragments of rock at the base of some high
mountain. The side walls (running south-west and north-east),
though exceedingly fractured, yet remained standing; but the vast
buttresses (at right angles to them, and therefore parallel to the
walls that fell) were in many cases cut clean off, as if by a
chisel, and hurled to the ground. Some square ornaments on the
coping of these same walls were moved by the earthquake into a
diagonal position. A similar circumstance was observed after an
earthquake at Valparaiso, Calabria, and other places, including
some of the ancient Greek temples. (14/1. M. Arago in "L'Institut"
1839 page 337. See also Miers's "Chile" volume 1 page 392; also
Lyell's "Principles of Geology" chapter 15 book 2.) This twisting
displacement at first appears to indicate a vorticose movement
beneath each point thus affected; but this is highly improbable.
May it not be caused by a tendency in each stone to arrange itself
in some particular position with respect to the lines of
vibration, - in a manner somewhat similar to pins on a sheet of
paper when shaken? Generally speaking, arched doorways or windows
stood much better than any other part of the buildings.
Nevertheless, a poor lame old man, who had been in the habit,
during trifling shocks, of crawling to a certain doorway, was this
time crushed to pieces.

I have not attempted to give any detailed description of the
appearance of Concepcion, for I feel that it is quite impossible to
convey the mingled feelings which I experienced. Several of the
officers visited it before me, but their strongest language failed
to give a just idea of the scene of desolation. It is a bitter and
humiliating thing to see works, which have cost man so much time
and labour, overthrown in one minute; yet compassion for the
inhabitants was almost instantly banished, by the surprise in
seeing a state of things produced in a moment of time, which one
was accustomed to attribute to a succession of ages. In my opinion,
we have scarcely beheld, since leaving England, any sight so deeply
interesting.

In almost every severe earthquake, the neighbouring waters of the
sea are said to have been greatly agitated. The disturbance seems
generally, as in the case of Concepcion, to have been of two kinds:
first, at the instant of the shock, the water swells high up on the
beach with a gentle motion, and then as quietly retreats; secondly,
some time afterwards, the whole body of the sea retires from the
coast, and then returns in waves of overwhelming force. The first
movement seems to be an immediate consequence of the earthquake
affecting differently a fluid and a solid, so that their respective
levels are slightly deranged: but the second case is a far more
important phenomenon. During most earthquakes, and especially
during those on the west coast of America, it is certain that the
first great movement of the waters has been a retirement. Some
authors have attempted to explain this, by supposing that the water
retains its level, whilst the land oscillates upwards; but surely
the water close to the land, even on a rather steep coast, would
partake of the motion of the bottom: moreover, as urged by Mr.
Lyell, similar movements of the sea have occurred at islands far
distant from the chief line of disturbance, as was the case with
Juan Fernandez during this earthquake, and with Madeira during the
famous Lisbon shock. I suspect (but the subject is a very obscure
one) that a wave, however produced, first draws the water from the
shore, on which it is advancing to break: I have observed that this
happens with the little waves from the paddles of a steam-boat. It
is remarkable that whilst Talcahuano and Callao (near Lima), both
situated at the head of large shallow bays, have suffered during
every severe earthquake from great waves, Valparaiso, seated close
to the edge of profoundly deep water, has never been overwhelmed,
though so often shaken by the severest shocks. From the great wave
not immediately following the earthquake, but sometimes after the
interval of even half an hour, and from distant islands being
affected similarly with the coasts near the focus of the
disturbance, it appears that the wave first rises in the offing;
and as this is of general occurrence, the cause must be general: I
suspect we must look to the line where the less disturbed waters of
the deep ocean join the water nearer the coast, which has partaken
of the movements of the land, as the place where the great wave is
first generated; it would also appear that the wave is larger or
smaller, according to the extent of shoal water which has been
agitated together with the bottom on which it rested.

The most remarkable effect of this earthquake was the permanent
elevation of the land; it would probably be far more correct to
speak of it as the cause. There can be no doubt that the land round
the Bay of Concepcion was upraised two or three feet; but it
deserves notice, that owing to the wave having obliterated the old
lines of tidal action on the sloping sandy shores, I could discover
no evidence of this fact, except in the united testimony of the
inhabitants, that one little rocky shoal, now exposed, was formerly
covered with water. At the island of S. Maria (about thirty miles
distant) the elevation was greater; on one part, Captain Fitz Roy
found beds of putrid mussel-shells STILL ADHERING TO THE ROCKS, ten
feet above high-water mark: the inhabitants had formerly dived at
lower-water spring-tides for these shells. The elevation of this
province is particularly interesting, from its having been the
theatre of several other violent earthquakes, and from the vast
numbers of sea-shells scattered over the land, up to a height of
certainly 600, and I believe, of 1000 feet. At Valparaiso, as I
have remarked, similar shells are found at the height of 1300 feet:
it is hardly possible to doubt that this great elevation has been
effected by successive small uprisings, such as that which
accompanied or caused the earthquake of this year, and likewise by
an insensibly slow rise, which is certainly in progress on some
parts of this coast.

The island of Juan Fernandez, 360 miles to the north-east, was, at
the time of the great shock of the 20th, violently shaken, so that
the trees beat against each other, and a volcano burst forth under
water close to the shore: these facts are remarkable because this
island, during the earthquake of 1751, was then also affected more
violently than other places at an equal distance from Concepcion,
and this seems to show some subterranean connexion between these
two points. Chiloe, about 340 miles southward of Concepcion,
appears to have been shaken more strongly than the intermediate
district of Valdivia, where the volcano of Villarica was noways
affected, whilst in the Cordillera in front of Chiloe two of the
volcanos burst forth at the same instant in violent action. These
two volcanos, and some neighbouring ones, continued for a long time
in eruption, and ten months afterwards were again influenced by an
earthquake at Concepcion. Some men cutting wood near the base of
one of these volcanos, did not perceive the shock of the 20th,
although the whole surrounding Province was then trembling; here we
have an eruption relieving and taking the place of an earthquake,
as would have happened at Concepcion, according to the belief of
the lower orders, if the volcano at Antuco had not been closed by
witchcraft. Two years and three-quarters afterwards Valdivia and
Chiloe were again shaken, more violently than on the 20th, and an
island in the Chonos Archipelago was permanently elevated more than
eight feet. It will give a better idea of the scale of these
phenomena, if (as in the case of the glaciers) we suppose them to
have taken place at corresponding distances in Europe: - then would
the land from the North Sea to the Mediterranean have been
violently shaken, and at the same instant of time a large tract of
the eastern coast of England would have been permanently elevated,
together with some outlying islands, - a train of volcanos on the
coast of Holland would have burst forth in action, and an eruption
taken place at the bottom of the sea, near the northern extremity
of Ireland - and lastly, the ancient vents of Auvergne, Cantal, and
Mont d'Or would each have sent up to the sky a dark column of
smoke, and have long remained in fierce action. Two years and
three-quarters afterwards, France, from its centre to the English
Channel, would have been again desolated by an earthquake, and an
island permanently upraised in the Mediterranean.

The space, from under which volcanic matter on the 20th was
actually erupted, is 720 miles in one line, and 400 miles in
another line at right angles to the first: hence, in all
probability, a subterranean lake of lava is here stretched out, of
nearly double the area of the Black Sea. From the intimate and
complicated manner in which the elevatory and eruptive forces were
shown to be connected during this train of phenomena, we may
confidently come to the conclusion that the forces which slowly and
by little starts uplift continents, and those which at successive
periods pour forth volcanic matter from open orifices, are
identical. From many reasons, I believe that the frequent quakings
of the earth on this line of coast are caused by the rending of the
strata, necessarily consequent on the tension of the land when
upraised, and their injection by fluidified rock. This rending and
injection would, if repeated often enough (and we know that
earthquakes repeatedly affect the same areas in the same manner),
form a chain of hills; - and the linear island of St. Mary, which
was upraised thrice the height of the neighbouring country, seems
to be undergoing this process. I believe that the solid axis of a
mountain differs in its manner of formation from a volcanic hill,
only in the molten stone having been repeatedly injected, instead
of having been repeatedly ejected. Moreover, I believe that it is
impossible to explain the structure of great mountain-chains, such
as that of the Cordillera, where the strata, capping the injected
axis of plutonic rock, have been thrown on their edges along
several parallel and neighbouring lines of elevation, except on
this view of the rock of the axis having been repeatedly injected,
after intervals sufficiently long to allow the upper parts or
wedges to cool and become solid; - for if the strata had been thrown
into their present highly-inclined, vertical, and even inverted
positions, by a single blow, the very bowels of the earth would
have gushed out; and instead of beholding abrupt mountain-axes of
rock solidified under great pressure, deluges of lava would have
flowed out at innumerable points on every line of elevation. (14/2.
For a full account of the volcanic phenomena which accompanied the
earthquake of the 20th, and for the conclusions deducible from
them, I must refer to Volume 5 of the "Geological Transactions.")





CHAPTER XV.

(PLATE 72. HIDE BRIDGE, SANTIAGO DE CHILE.)

Valparaiso.
Portillo Pass.
Sagacity of mules.
Mountain-torrents.
Mines, how discovered.
Proofs of the gradual elevation of the Cordillera.
Effect of snow on rocks.
Geological structure of the two main ranges, their distinct
origin and upheaval.
Great subsidence.
Red snow.
Winds.
Pinnacles of snow.
Dry and clear atmosphere.
Electricity.
Pampas.
Zoology of the opposite sides of the Andes.
Locusts.
Great Bugs.
Mendoza.
Uspallata Pass.
Silicified trees buried as they grew.
Incas Bridge.
Badness of the passes exaggerated.
Cumbre.
Casuchas.
Valparaiso.

PASSAGE OF THE CORDILLERA.

MARCH 7, 1835.



We stayed three days at Concepcion, and then sailed for Valparaiso.
The wind being northerly, we only reached the mouth of the harbour
of Concepcion before it was dark. Being very near the land, and a
fog coming on, the anchor was dropped. Presently a large American
whaler appeared close alongside of us; and we heard the Yankee
swearing at his men to keep quiet, whilst he listened for the
breakers. Captain Fitz Roy hailed him, in a loud clear voice, to
anchor where he then was. The poor man must have thought the voice
came from the shore: such a Babel of cries issued at once from the
ship - every one hallooing out, "Let go the anchor! veer cable!
shorten sail!" It was the most laughable thing I ever heard. If the
ship's crew had been all captains, and no men, there could not have
been a greater uproar of orders. We afterwards found that the mate
stuttered: I suppose all hands were assisting him in giving his
orders.

On the 11th we anchored at Valparaiso, and two days afterwards I
set out to cross the Cordillera. I proceeded to Santiago, where Mr.
Caldcleugh most kindly assisted me in every possible way in making
the little preparations which were necessary. In this part of Chile
there are two passes across the Andes to Mendoza: the one most
commonly used, namely, that of Aconcagua or Uspallata - is situated
some way to the north; the other, called the Portillo, is to the
south, and nearer, but more lofty and dangerous.

MARCH 18, 1835.

(PLATE 73. CHILENOS.)

We set out for the Portillo pass. Leaving Santiago we crossed the
wide burnt-up plain on which that city stands, and in the afternoon
arrived at the Maypu, one of the principal rivers in Chile. The
valley, at the point where it enters the first Cordillera, is
bounded on each side by lofty barren mountains; and although not
broad, it is very fertile. Numerous cottages were surrounded by
vines, and by orchards of apple, nectarine, and peach-trees - their
boughs breaking with the weight of the beautiful ripe fruit. In the
evening we passed the custom-house, where our luggage was examined.
The frontier of Chile is better guarded by the Cordillera than by
the waters of the sea. There are very few valleys which lead to the
central ranges, and the mountains are quite impassable in other
parts by beasts of burden. The custom-house officers were very
civil, which was perhaps partly owing to the passport which the
President of the Republic had given me; but I must express my
admiration at the natural politeness of almost every Chileno. In
this instance, the contrast with the same class of men in most
other countries was strongly marked. I may mention an anecdote with
which I was at the time much pleased: we met near Mendoza a little
and very fat negress, riding astride on a mule. She had a goitre so
enormous that it was scarcely possible to avoid gazing at her for a
moment; but my two companions almost instantly, by way of apology,
made the common salute of the country by taking off their hats.
Where would one of the lower or higher classes in Europe have shown
such feeling politeness to a poor and miserable object of a
degraded race?

At night we slept at a cottage. Our manner of travelling was
delightfully independent. In the inhabited parts we bought a little
firewood, hired pasture for the animals, and bivouacked in the
corner of the same field with them. Carrying an iron pot, we cooked
and ate our supper under a cloudless sky, and knew no trouble. My
companions were Mariano Gonzales, who had formerly accompanied me
in Chile, and an "arriero," with his ten mules and a "madrina." The
madrina (or godmother) is a most important personage: she is an old
steady mare, with a little bell round her neck; and wherever she
goes, the mules, like good children, follow her. The affection of
these animals for their madrinas saves infinite trouble. If several
large troops are turned into one field to graze, in the morning the
muleteers have only to lead the madrinas a little apart, and tinkle
their bells; and although there may be two or three hundred
together, each mule immediately knows the bell of its own madrina,
and comes to her. It is nearly impossible to lose an old mule; for
if detained for several hours by force, she will, by the power of
smell, like a dog, track out her companions, or rather the madrina,
for, according to the muleteer, she is the chief object of
affection. The feeling, however, is not of an individual nature;
for I believe I am right in saying that any animal with a bell will
serve as a madrina. In a troop each animal carries on a level road,
a cargo weighing 416 pounds (more than 29 stone), but in a
mountainous country 100 pounds less; yet with what delicate slim
limbs, without any proportional bulk of muscle, these animals
support so great a burden! The mule always appears to me a most
surprising animal. That a hybrid should possess more reason,
memory, obstinacy, social affection, powers of muscular endurance,
and length of life, than either of its parents, seems to indicate
that art has here outdone nature. Of our ten animals, six were
intended for riding, and four for carrying cargoes, each taking
turn about. We carried a good deal of food in case we should be
snowed up, as the season was rather late for passing the Portillo.

MARCH 19, 1835.

We rode during this day to the last, and therefore most elevated,
house in the valley. The number of inhabitants became scanty; but
wherever water could be brought on the land, it was very fertile.
All the main valleys in the Cordillera are characterised by having,
on both sides, a fringe or terrace of shingle and sand, rudely
stratified, and generally of considerable thickness. These fringes
evidently once extended across the valleys and were united; and the
bottoms of the valleys in northern Chile, where there are no
streams, are thus smoothly filled up. On these fringes the roads
are generally carried, for their surfaces are even, and they rise
with a very gentle slope up the valleys: hence, also, they are
easily cultivated by irrigation. They may be traced up to a height
of between 7000 and 9000 feet, where they become hidden by the
irregular piles of debris. At the lower end or mouths of the
valleys they are continuously united to those land-locked plains
(also formed of shingle) at the foot of the main Cordillera, which
I have described in a former chapter as characteristic of the
scenery of Chile, and which were undoubtedly deposited when the sea
penetrated Chile, as it now does the more southern coasts. No one
fact in the geology of South America interested me more than these
terraces of rudely-stratified shingle. They precisely resemble in
composition the matter which the torrents in each valley would
deposit if they were checked in their course by any cause, such as
entering a lake or arm of the sea; but the torrents, instead of
depositing matter, are now steadily at work wearing away both the
solid rock and these alluvial deposits, along the whole line of
every main valley and side valley. It is impossible here to give
the reasons, but I am convinced that the shingle terraces were
accumulated, during the gradual elevation of the Cordillera, by the
torrents delivering, at successive levels, their detritus on the



Online LibraryCharles DarwinThe Voyage of the Beagle → online text (page 31 of 51)