The Voyage of the Beagle
by
Charles Darwin
Part 11 out of 11
has, I believe, caused the death of those coral-groves, which
under the former and more open condition of the outer reef
has attained the utmost possible limit of upward growth.
A few miles north of Keeling there is another small atoll,
the lagoon of which is nearly filled up with coral-mud. Captain
Ross found embedded in the conglomerate on the outer
coast, a well-rounded fragment of greenstone, rather larger
than a man's head: he and the men with him were so much
surprised at this, that they brought it away and preserved it
as a curiosity. The occurrence of this one stone, where
every other particle of matter is calcareous, certainly is very
puzzling. The island has scarcely ever been visited, nor is it
probable that a ship had been wrecked there. From the absence
of any better explanation, I came to the conclusion that
it must have come entangled in the roots of some large tree:
when, however, I considered the great distance from the
nearest land, the combination of chances against a stone thus
being entangled, the tree washed into the sea, floated so far,
then landed safely, and the stone finally so embedded as to
allow of its discovery, I was almost afraid of imagining a
means of transport apparently so improbable. It was therefore
with great interest that I found Chamisso, the justly
distinguished naturalist who accompanied Kotzebue, stating
that the inhabitants of the Radack archipelago, a group of
lagoon-islands in the midst of the Pacific, obtained stones
for sharpening their instruments by searching the roots of
trees which are cast upon the beach. It will be evident that
this must have happened several times, since laws have been
established that such stones belong to the chief, and a
punishment is inflicted on any one who attempts to steal them.
When the isolated position of these small islands in the
midst of a vast ocean -- their great distance from any land
excepting that of coral formation, attested by the value
which the inhabitants, who are such bold navigators, attach
to a stone of any kind, [7] -- and the slowness of the currents
of the open sea, are all considered, the occurrence of pebbles
thus transported does appear wonderful. Stones may often
be thus carried; and if the island on which they are stranded
is constructed of any other substance besides coral, they
would scarcely attract attention, and their origin at least
would never be guessed. Moreover, this agency may long
escape discovery from the probability of trees, especially
those loaded with stones, floating beneath the surface. In
the channels of Tierra del Fuego large quantities of drift
timber are cast upon the beach, yet it is extremely rare to
meet a tree swimming on the water. These facts may possibly
throw light on single stones, whether angular or rounded,
occasionally found embedded in fine sedimentary masses.
During another day I visited West Islet, on which the
vegetation was perhaps more luxuriant than on any other.
The cocoa-nut trees generally grow separate, but here the
young ones flourished beneath their tall parents, and formed
with their long and curved fronds the most shady arbours.
Those alone who have tried it, know how delicious it is to
be seated in such shade, and drink the cool pleasant fluid
of the cocoa-nut. In this island there is a large bay-like
space, composed of the finest white sand: it is quite level
and is only covered by the tide at high water; from this
large bay smaller creeks penetrate the surrounding woods.
To see a field of glittering white sand, representing water,
with the cocoa-nut trees extending their tall and waving
trunks around the margin, formed a singular and very pretty
view.
I have before alluded to a crab which lives on the cocoa-nuts;
it is very common on all parts of the dry land, and
grows to a monstrous size: it is closely allied or identical
with the Birgos latro. The front pair of legs terminate in
very strong and heavy pincers, and the last pair are fitted
with others weaker and much narrower. It would at first
be thought quite impossible for a crab to open a strong
cocoa-nut covered with the husk; but Mr. Liesk assures me
that he has repeatedly seen this effected. The crab begins
by tearing the husk, fibre by fibre, and always from that
end under which the three eye-holes are situated; when this
is completed, the crab commences hammering with its heavy
claws on one of the eye-holes till an opening is made. Then
turning round its body, by the aid of its posterior and narrow
pair of pincers, it extracts the white albuminous substance.
I think this is as curious a case of instinct as ever
I heard of, and likewise of adaptation in structure between
two objects apparently so remote from each other in the
scheme of nature, as a crab and a cocoa-nut tree. The
Birgos is diurnal in its habits; but every night it is said to
pay a visit to the sea, no doubt for the purpose of moistening
its branchiae. The young are likewise hatched, and live for
some time, on the coast. These crabs inhabit deep burrows,
which they hollow out beneath the roots of trees; and where
they accumulate surprising quantities of the picked fibres
of the cocoa-nut husk, on which they rest as on a bed. The
Malays sometimes take advantage of this, and collect the
fibrous mass to use as junk. These crabs are very good to
eat; moreover, under the tail of the larger ones there is a
mass of fat, which, when melted, sometimes yields as much
as a quart bottle full of limpid oil. It has been stated by
some authors that the Birgos crawls up the cocoa-nut trees
for the purpose of stealing the nuts: I very much doubt the
possibility of this; but with the Pandanus [8] the task would be
very much easier. I was told by Mr. Liesk that on these
islands the Birgos lives only on the nuts which have fallen
to the ground.
Captain Moresby informs me that this crab inhabits the
Chagos and Seychelle groups, but not the neighbouring Maldiva
archipelago. It formerly abounded at Mauritius, but
only a few small ones are now found there. In the Pacific,
this species, or one with closely allied habits, is said [9] to
inhabit a single coral island, north of the Society group. To
show the wonderful strength of the front pair of pincers, I
may mention, that Captain Moresby confined one in a strong
tin-box, which had held biscuits, the lid being secured with
wire; but the crab turned down the edges and escaped. In
turning down the edges, it actually punched many small
holes quite through the tin!
I was a good deal surprised by finding two species of
coral of the genus Millepora (M. complanata and alcicornis),
possessed of the power of stinging. The stony branches or
plates, when taken fresh from the water, have a harsh feel
and are not slimy, although possessing a strong and disagreeable
smell. The stinging property seems to vary in
different specimens: when a piece was pressed or rubbed on
the tender skin of the face or arm, a pricking sensation was
usually caused, which came on after the interval of a second,
and lasted only for a few minutes. One day, however, by
merely touching my face with one of the branches, pain was
instantaneously caused; it increased as usual after a few
seconds, and remaining sharp for some minutes, was perceptible
for half an hour afterwards. The sensation was as
bad as that from a nettle, but more like that caused by the
Physalia or Portuguese man-of-war. Little red spots were
produced on the tender skin of the arm, which appeared as if
they would have formed watery pustules, but did not. M.
Quoy mentions this case of the Millepora; and I have heard
of stinging corals in the West Indies. Many marine animals
seem to have this power of stinging: besides the Portuguese
man-of-war, many jelly-fish, and the Aplysia or sea-slug
of the Cape de Verd Islands, it is stated in the voyage
of the Astrolabe, that an Actinia or sea-anemone, as well as
a flexible coralline allied to Sertularia, both possess this
means of offence or defence. In the East Indian sea, a
stinging sea-weed is said to be found.
Two species of fish, of the genus Scarus, which are common
here, exclusively feed on coral: both are coloured of a
splendid bluish-green, one living invariably in the lagoon,
and the other amongst the outer breakers. Mr. Liesk assured
us, that he had repeatedly seen whole shoals grazing with
their strong bony jaws on the tops of the coral branches: I
opened the intestines of several, and found them distended
with yellowish calcareous sandy mud. The slimy disgusting
Holuthuriae (allied to our star-fish), which the Chinese
gourmands are so fond of, also feed largely, as I am informed by
Dr. Allan, on corals; and the bony apparatus within their
bodies seems well adapted for this end. These Holuthuriae,
the fish, the numerous burrowing shells, and nereidous
worms, which perforate every block of dead coral, must be
very efficient agents in producing the fine white mud which
lies at the bottom and on the shores of the lagoon. A portion,
however, of this mud, which when wet resembled
pounded chalk, was found by Professor Ehrenberg to be
partly composed of siliceous-shielded infusoria.
April 12th. -- In the morning we stood out of the lagoon
on our passage to the Isle of France. I am glad we have
visited these islands: such formations surely rank high
amongst the wonderful objects of this world. Captain Fitz
Roy found no bottom with a line 7200 feet in length, at the
distance of only 2200 yards from the shore; hence this island
forms a lofty submarine mountain, with sides steeper even
than those of the most abrupt volcanic cone. The saucer-shaped
summit is nearly ten miles across; and every single
atom, [10] from the least particle to the largest fragment of
rock, in this great pile, which however is small compared
with very many other lagoon-islands, bears the stamp of
having been subjected to organic arrangement. We feel surprise
when travellers tell us of the vast dimensions of the
Pyramids and other great ruins, but how utterly insignificant
are the greatest of these, when compared to these mountains
of stone accumulated by the agency of various minute
and tender animals! This is a wonder which does not at
first strike the eye of the body, but, after reflection,
the eye of reason.
I will now give a very brief account of the three great
classes of coral-reefs; namely, Atolls, Barrier, and Fringing-
reefs, and will explain my views [11] on their formation. Almost
every voyager who has crossed the Pacific has expressed
his unbounded astonishment at the lagoon-islands, or
as I shall for the future call them by their Indian name of
atolls, and has attempted some explanation. Even as long
ago as the year 1605, Pyrard de Laval well exclaimed, "C'est
[picture]
une merveille de voir chacun de ces atollons, environne d'un
grand banc de pierre tout autour, n'y ayant point d'artifice
humain." The accompanying sketch of Whitsunday Island
in the Pacific, copied from, Capt. Beechey's admirable Voyage,
gives but a faint idea of the singular aspect of an atoll:
it is one of the smallest size, and has its narrow islets united
together in a ring. The immensity of the ocean, the fury of
the breakers, contrasted with the lowness of the land and the
smoothness of the bright green water within the lagoon, can
hardly be imagined without having been seen.
The earlier voyagers fancied that the coral-building animals
instinctively built up their great circles to afford themselves
protection in the inner parts; but so far is this from
the truth, that those massive kinds, to whose growth on the
exposed outer shores the very existence of the reef depends,
cannot live within the lagoon, where other delicately-branching
kinds flourish. Moreover, on this view, many species
of distinct genera and families are supposed to combine for
one end; and of such a combination, not a single instance
can be found in the whole of nature. The theory that has
been most generally received is, that atolls are based on
submarine craters; but when we consider the form and size of
some, the number, proximity, and relative positions of others,
this idea loses its plausible character: thus Suadiva atoll is
44 geographical miles in diameter in one line, by 34 miles in
another line; Rimsky is 54 by 20 miles across, and it has a
strangely sinuous margin; Bow atoll is 30 miles long, and on
an average only 6 in width; Menchicoff atoll consists of three
atolls united or tied together. This theory, moreover, is
totally inapplicable to the northern Maldiva atolls in the
Indian Ocean (one of which is 88 miles in length, and between 10
and 20 in breadth), for they are not bounded like ordinary
atolls by narrow reefs, but by a vast number of separate
little atolls; other little atolls rising out of the great
central lagoon-like spaces. A third and better theory was
advanced by Chamisso, who thought that from the corals growing
more vigorously where exposed to the open sea, as undoubtedly is
the case, the outer edges would grow up from the general
foundation before any other part, and that this would account
for the ring or cup-shaped structure. But we shall
immediately see, that in this, as well as in the crater-theory,
a most important consideration has been overlooked, namely,
on what have the reef-building corals, which cannot live at
a great depth, based their massive structures?
Numerous soundings were carefully taken by Captain Fitz
Roy on the steep outside of Keeling atoll, and it was found
that within ten fathoms, the prepared tallow at the bottom
of the lead, invariably came up marked with the impression
of living corals, but as perfectly clean as if it had been
dropped on a carpet of turf; as the depth increased, the
impressions became less numerous, but the adhering particles
of sand more and more numerous, until at last it was evident
that the bottom consisted of a smooth sandy layer: to carry
on the analogy of the turf, the blades of grass grew thinner
and thinner, till at last the soil was so sterile, that nothing
sprang from it. From these observations, confirmed by many
others, it may be safely inferred that the utmost depth at
which corals can construct reefs is between 20 and 30 fathoms.
Now there are enormous areas in the Pacific and Indian
Ocean, in which every single island is of coral formation,
and is raised only to that height to which the waves can
throw up fragments, and the winds pile up sand. Thus
Radack group of atolls is an irregular square, 520 miles long
and 240 broad; the Low Archipelago is elliptic-formed, 840
miles in its longer, and 420 in its shorter axis: there are
other small groups and single low islands between these two
archipelagoes, making a linear space of ocean actually more
than 4000 miles in length, in which not one single island
rises above the specified height. Again, in the Indian Ocean
there is a space of ocean 1500 miles in length, including
three archipelagoes, in which every island is low and of
coral formation. From the fact of the reef-building corals
not living at great depths, it is absolutely certain that
throughout these vast areas, wherever there is now an atoll,
a foundation must have originally existed within a depth of
from 20 to 30 fathoms from the surface. It is improbable in
the highest degree that broad, lofty, isolated, steep-sided
banks of sediment, arranged in groups and lines hundreds of
leagues in length, could have been deposited in the central
and profoundest parts of the Pacific and Indian Oceans, at
an immense distance from any continent, and where the
water is perfectly limpid. It is equally improbable that the
elevatory forces should have uplifted throughout the above
vast areas, innumerable great rocky banks within 20 to 30
fathoms, or 120 to 180 feet, of the surface of the sea, and
not one single point above that level; for where on the whole
surface of the globe can we find a single chain of mountains,
even a few hundred miles in length, with their many summits
rising within a few feet of a given level, and not one
pinnacle above it? If then the foundations, whence the atoll-
building corals sprang, were not formed of sediment, and if
they were not lifted up to the required level, they must of
necessity have subsided into it; and this at once solves the
difficulty. For as mountain after mountain, and island after
island, slowly sank beneath the water, fresh bases would be
successively afforded for the growth of the corals. It is
impossible here to enter into all the necessary details, but I
venture to defy [12] any one to explain in any other manner
how it is possible that numerous islands should be distributed
throughout vast areas -- all the islands being low -- all being
built of corals, absolutely requiring a foundation within a
limited depth from the surface.
Before explaining how atoll-formed reefs acquire their
peculiar structure, we must turn to the second great class,
namely, Barrier-reefs. These either extend in straight lines
in front of the shores of a continent or of a large island, or
they encircle smaller islands; in both cases, being separated
from the land by a broad and rather deep channel of water,
analogous to the lagoon within an atoll. It is remarkable
how little attention has been paid to encircling barrier-reefs;
yet they are truly wonderful structures. The following sketch
represents part of the barrier encircling the island of Bolabola
in the Pacific, as seen from one of the central peaks.
In this instance the whole line of reef has been converted
into land; but usually a snow-white line of great breakers,
with only here and there a single low islet crowned with
cocoa-nut trees, divides the dark heaving waters of the ocean
from the light-green expanse of the lagoon-channel. And
the quiet waters of this channel generally bathe a fringe of
low alluvial soil, loaded with the most beautiful productions
of the tropics, and lying at the foot of the wild, abrupt,
central mountains.
Encircling barrier-reefs are of all sizes, from three miles
to no less than forty-four miles in diameter; and that which
fronts one side, and encircles both ends, of New Caledonia,
is 400 miles long. Each reef includes one, two, or several
rocky islands of various heights; and in one instance, even
as many as twelve separate islands. The reef runs at a
greater or less distance from the included land; in the
Society archipelago generally from one to three or four
miles; but at Hogoleu the reef is 20 miles on the southern
side, and 14 miles on the opposite or northern side, from the
included islands. The depth within the lagoon-channel also
varies much; from 10 to 30 fathoms may be taken as an
average; but at Vanikoro there are spaces no less than 56
fathoms or 363 feet deep. Internally the reef either slopes
gently into the lagoon-channel, or ends in a perpendicular
wall sometimes between two and three hundred feet under
water in height: externally the reef rises, like an atoll, with
extreme abruptness out of the profound depths of the ocean.
What can be more singular than these structures? We see
[picture]
an island, which may be compared to a castle situated on the
summit of a lofty submarine mountain, protected by a great
wall of coral-rock, always steep externally and sometimes
internally, with a broad level summit, here and there breached
by a narrow gateway, through which the largest ships can
enter the wide and deep encircling moat.
As far as the actual reef of coral is concerned, there is not
the smallest difference, in general size, outline, grouping,
and even in quite trifling details of structure, between a
barrier and an atoll. The geographer Balbi has well remarked,
that an encircled island is an atoll with high land rising out
of its lagoon; remove the land from within, and a perfect
atoll is left.
But what has caused these reefs to spring up at such
great distances from the shores of the included islands? It
cannot be that the corals will not grow close to the land;
for the shores within the lagoon-channel, when not surrounded
by alluvial soil, are often fringed by living reefs;
and we shall presently see that there is a whole class, which
I have called Fringing Reefs from their close attachment
to the shores both of continents and of islands. Again, on
what have the reef-building corals, which cannot live at
great depths, based their encircling structures? This is a
great apparent difficulty, analogous to that in the case of
atolls, which has generally been overlooked. It will be
perceived more clearly by inspecting the following sections
which are real ones, taken in north and south lines, through
the islands with their barrier-reefs, of Vanikoro, Gambier,
and Maurua; and they are laid down, both vertically and
horizontally, on the same scale of a quarter of an inch to
a mile.
It should be observed that the sections might have been
taken in any direction through these islands, or through
[picture]
many other encircled islands, and the general features would
have been the same. Now, bearing in mind that reef-building
coral cannot live at a greater depth than from 20 to 30
fathoms, and that the scale is so small that the plummets on
the right hand show a depth of 200 fathoms, on what are
these barrier-reefs based? Are we to suppose that each
island is surrounded by a collar-like submarine ledge of rock,
or by a great bank of sediment, ending abruptly where the
reef ends?
If the sea had formerly eaten deeply into the islands,
before they were protected by the reefs, thus having
left a shallow ledge round them under water, the present
shores would have been invariably bounded by great precipices,
but this is most rarely the case. Moreover, on this
notion, it is not possible to explain why the corals should
have sprung up, like a wall, from the extreme outer margin
of the ledge, often leaving a broad space of water within,
too deep for the growth of corals. The accumulation of a
wide bank of sediment all round these islands, and generally
widest where the included islands are smallest, is highly
improbable, considering their exposed positions in the central
and deepest parts of the ocean. In the case of the barrier-reef
of New Caledonia, which extends for 150 miles beyond
the northern point of the islands, in the same straight line
with which it fronts the west coast, it is hardly possible to
believe that a bank of sediment could thus have been
straightly deposited in front of a lofty island, and so far
beyond its termination in the open sea. Finally, if we look
to other oceanic islands of about the same height and of similar
geological constitution, but not encircled by coral-reefs,
we may in vain search for so trifling a circumambient
depth as 30 fathoms, except quite near to their shores; for
usually land that rises abruptly out of water, as do most of
the encircled and non-encircled oceanic islands, plunges
abruptly under it. On what then, I repeat, are these barrier
reefs based? Why, with their wide and deep moat-like channels,
do they stand so far from the included land? We shall
soon see how easily these difficulties disappear.
We come now to our third class of Fringing-reefs, which
will require a very short notice. Where the land slopes abruptly
under water, these reefs are only a few yards in width,
forming a mere ribbon or fringe round the shores: where
the land slopes gently under the water the reef extends
further, sometimes even as much as a mile from the land;
but in such cases the soundings outside the reef always show
that the submarine prolongation of the land is gently inclined.
In fact, the reefs extend only to that distance from the shore,
at which a foundation within the requisite depth from 20 to
30 fathoms is found. As far as the actual reef is concerned,
there is no essential difference between it and that forming
a barrier or an atoll: it is, however, generally of less width,
and consequently few islets have been formed on it. From
the corals growing more vigorously on the outside, and from
the noxious effect of the sediment washed inwards, the outer
edge of the reef is the highest part, and between it and the
land there is generally a shallow sandy channel a few feet in
depth. Where banks or sediments have accumulated near to
the surface, as in parts of the West Indies, they sometimes
become fringed with corals, and hence in some degree resemble
lagoon-islands or atolls, in the same manner as fringing-reefs,
surrounding gently sloping islands, in some degree resemble
barrier-reefs.
No theory on the formation of coral-reefs can be considered
satisfactory which does not include the three great
[picture]
classes. We have seen that we are driven to believe in the
subsidence of those vast areas, interspersed with low islands,
of which not one rises above the height to which the wind and
waves can throw up matter, and yet are constructed by animals
requiring a foundation, and that foundation to lie at
no great depth. Let us then take an island surrounded by
fringing-reefs, which offer no difficulty in their structure;
and let this island with its reefs, represented by the unbroken
lines in the woodcut, slowly subside. Now, as the island
sinks down, either a few feet at a time or quite insensibly,
we may safely infer, from what is known of the conditions
favourable to the growth of coral, that the living masses,
bathed by the surf on the margin of the reef, will soon regain
the surface. The water, however, will encroach little by little
on the shore, the island becoming lower and smaller, and the
space between the inner edge of the reef and the beach
proportionately broader. A section of the reef and island in
this state, after a subsidence of several hundred feet, is given
by the dotted lines. Coral islets are supposed to have been
formed on the reef; and a ship is anchored in the
lagoon-channel. This channel will be more or less deep,
according to the rate of subsidence, to the amount of sediment
accumulated in it, and to the growth of the delicately branched
corals which can live there. The section in this state resembles
in every respect one drawn through an encircled island: in fact,
it is a real section (on the scale of .517 of an inch to a mile)
through Bolabola in the Pacific. We can now at once see
why encircling barrier-reefs stand so far from the shores
which they front. We can also perceive, that a line drawn
perpendicularly down from the outer edge of the new reef,
to the foundation of solid rock beneath the old fringing-reef,
will exceed by as many feet as there have been feet of
subsidence, that small limit of depth at which the effective
corals can live: -- the little architects having built up their
great wall-like mass, as the whole sank down, upon a basis
formed of other corals and their consolidated fragments.
Thus the difficulty on this head, which appeared so great,
disappears.
If, instead of an island, we had taken the shore of a continent
fringed with reefs, and had imagined it to have subsided,
a great straight barrier, like that of Australia or New
Caledonia, separated from the land by a wide and deep channel,
would evidently have been the result.
Let us take our new encircling barrier-reef, of which the
section is now represented by unbroken lines, and which, as
I have said, is a real section through Bolabola, and let it go
on subsiding. As the barrier-reef slowly sinks down, the
corals will go on vigorously growing upwards; but as the
island sinks, the water will gain inch by inch on the shore --
the separate mountains first forming separate islands within
[picture]
one great reef -- and finally, the last and highest pinnacle
disappearing. The instant this takes place, a perfect atoll
is formed: I have said, remove the high land from within an
encircling barrier-reef, and an atoll is left, and the land has
been removed. We can now perceive how it comes that
atolls, having sprung from encircling barrier-reefs, resemble
them in general size, form, in the manner in which they are
grouped together, and in their arrangement in single or
double lines; for they may be called rude outline charts of
the sunken islands over which they stand. We can further
see how it arises that the atolls in the Pacific and Indian
Oceans extend in lines parallel to the generally prevailing
strike of the high islands and great coast-lines of those
oceans. I venture, therefore, to affirm, that on the theory of
the upward growth of the corals during the sinking of the
land, [13] all the leading features in those wonderful
structures, the lagoon-islands or atolls, which have so long
excited the attention of voyagers, as well as in the no less
wonderful barrier-reefs, whether encircling small islands or
stretching for hundreds of miles along the shores of a
continent, are simply explained.
It may be asked, whether I can offer any direct evidence
of the subsidence of barrier-reefs or atolls; but it must be
borne in mind how difficult it must ever be to detect a
movement, the tendency of which is to hide under water the part
affected. Nevertheless, at Keeling atoll I observed on all
sides of the lagoon old cocoa-nut trees undermined and falling;
and in one place the foundation-posts of a shed, which
the inhabitants asserted had stood seven years before just
above high-water mark, but now was daily washed by every
tide: on inquiry I found that three earthquakes, one of them
severe, had been felt here during the last ten years. At
Vanikoro, the lagoon-channel is remarkably deep, scarcely
any alluvial soil has accumulated at the foot of the lofty
included mountains, and remarkably few islets have been
formed by the heaping of fragments and sand on the wall-like
barrier reef; these facts, and some analogous ones, led
me to believe that this island must lately have subsided and
the reef grown upwards: here again earthquakes are frequent
and very severe. In the Society archipelago, on the
other hand, where the lagoon-channels are almost choked up,
where much low alluvial land has accumulated, and where in
some cases long islets have been formed on the barrier-reefs
-- facts all showing that the islands have not very lately
subsided -- only feeble shocks are most rarely felt. In these
coral formations, where the land and water seem struggling
for mastery, it must be ever difficult to decide between the
effects of a change in the set of the tides and of a slight
subsidence: that many of these reefs and atolls are subject to
changes of some kind is certain; on some atolls the islets
appear to have increased greatly within a late period; on
others they have been partially or wholly washed away. The
inhabitants of parts of the Maldiva archipelago know the
date of the first formation of some islets; in other parts, the
corals are now flourishing on water-washed reefs, where
holes made for graves attest the former existence of inhabited
land. It is difficult to believe in frequent changes in the
tidal currents of an open ocean; whereas, we have in the
earthquakes recorded by the natives on some atolls, and in
the great fissures observed on other atolls, plain evidence of
changes and disturbances in progress in the subterranean
regions.
It is evident, on our theory, that coasts merely fringed by
reefs cannot have subsided to any perceptible amount; and
therefore they must, since the growth of their corals, either
have remained stationary or have been upheaved. Now, it
is remarkable how generally it can be shown, by the presence
of upraised organic remains, that the fringed islands have
been elevated: and so far, this is indirect evidence in favour
of our theory. I was particularly struck with this fact, when
I found, to my surprise, that the descriptions given by MM.
Quoy and Gaimard were applicable, not to reefs in general
as implied by them, but only to those of the fringing class;
my surprise, however, ceased when I afterwards found that,
by a strange chance, all the several islands visited by these
eminent naturalists, could be shown by their own statements
to have been elevated within a recent geological era.
Not only the grand features in the structure of barrier-reefs
and of atolls, and to their likeness to each other in form,
size, and other characters, are explained on the theory of
subsidence -- which theory we are independently forced to
admit in the very areas in question, from the necessity of
finding bases for the corals within the requisite depth -- but
many details in structure and exceptional cases can thus also
be simply explained. I will give only a few instances. In
barrier-reefs it has long been remarked with surprise, that
the passages through the reef exactly face valleys in the
included land, even in cases where the reef is separated
from the land by a lagoon-channel so wide and so much
deeper than the actual passage itself, that it seems hardly
possible that the very small quantity of water or sediment
brought down could injure the corals on the reef. Now,
every reef of the fringing class is breached by a narrow
gateway in front of the smallest rivulet, even if dry during
the greater part of the year, for the mud, sand, or gravel,
occasionally washed down kills the corals on which it is
deposited. Consequently, when an island thus fringed subsides,
though most of the narrow gateways will probably
become closed by the outward and upward growth of the
corals, yet any that are not closed (and some must always be
kept open by the sediment and impure water flowing out of
the lagoon-channel) will still continue to front exactly the
upper parts of those valleys, at the mouths of which the
original basal fringing-reef was breached.
We can easily see how an island fronted only on one side, or on
one side with one end or both ends encircled by barrier-reefs,
might after long-continued subsidence be converted
either into a single wall-like reef, or into an atoll with a
great straight spur projecting from it, or into two or three
atolls tied together by straight reefs -- all of which
exceptional cases actually occur. As the reef-building corals
require food, are preyed upon by other animals, are killed by
sediment, cannot adhere to a loose bottom, and may be easily
carried down to a depth whence they cannot spring up again,
we need feel no surprise at the reefs both of atolls and
barriers becoming in parts imperfect. The great barrier of
New Caledonia is thus imperfect and broken in many parts;
hence, after long subsidence, this great reef would not produce
one great atoll 400 miles in length, but a chain or
archipelago of atolls, of very nearly the same dimension with
those in the Maldiva archipelago. Moreover, in an atoll once
breached on opposite sides, from the likelihood of the oceanic
and tidal currents passing straight through the breaches, it
is extremely improbable that the corals, especially during
continued subsidence, would ever be able again to unite the
rim; if they did not, as the whole sank downwards, one atoll
would be divided into two or more. In the Maldiva archipelago
there are distinct atolls so related to each other in
position, and separated by channels either unfathomable or
very deep (the channel between Ross and Ari atolls is 150
fathoms, and that between the north and south Nillandoo
atolls is 200 fathoms in depth), that it is impossible to look
at a map of them without believing that they were once
more intimately related. And in this same archipelago,
Mahlos-Mahdoo atoll is divided by a bifurcating channel
from 100 to 132 fathoms in depth, in such a manner, that
it is scarcely possible to say whether it ought strictly to
be called three separate atolls, or one great atoll not yet
finally divided.
I will not enter on many more details; but I must remark
that the curious structure of the northern Maldiva atolls
receives (taking into consideration the free entrance of the
sea through their broken margins) a simple explanation in
the upward and outward growth of the corals, originally
based both on small detached reefs in their lagoons, such as
occur in common atolls, and on broken portions of the linear
marginal reef, such as bounds every atoll of the ordinary
form. I cannot refrain from once again remarking on the
singularity of these complex structures -- a great sandy and
generally concave disk rises abruptly from the unfathomable
ocean, with its central expanse studded, and its edge
symmetrically bordered with oval basins of coral-rock just
lipping the surface of the sea, sometimes clothed with
vegetation, and each containing a lake of clear water!
One more point in detail: as in the two neighbouring
archipelagoes corals flourish in one and not in the other, and
as so many conditions before enumerated must affect their
existence, it would be an inexplicable fact if, during the
changes to which earth, air, and water are subjected, the
reef-building corals were to keep alive for perpetuity on any
one spot or area. And as by our theory the areas including
atolls and barrier-reefs are subsiding, we ought occasionally to
find reefs both dead and submerged. In all reefs, owing to the
sediment being washed out of the lagoon-channel to leeward,
that side is least favourable to the long-continued vigorous
growth of the corals; hence dead portions of reef not
unfrequently occur on the leeward side; and these, though still
retaining their proper wall-like form, are now in several
instances sunk several fathoms beneath the surface. The
Chagos group appears from some cause, possibly from the
subsidence having been too rapid, at present to be much less
favourably circumstanced for the growth of reefs than formerly:
one atoll has a portion of its marginal reef, nine miles
in length, dead and submerged; a second has only a few
quite small living points which rise to the surface, a third
and fourth are entirely dead and submerged; a fifth is a
mere wreck, with its structure almost obliterated. It is
remarkable that in all these cases, the dead reefs and portions
of reef lie at nearly the same depth, namely, from six to
eight fathoms beneath the surface, as if they had been carried
down by one uniform movement. One of these "half-drowned
atolls," so called by Capt. Moresby (to whom I
am indebted for much invaluable information), is of vast
size, namely, ninety nautical miles across in one direction,
and seventy miles in another line; and is in many respects
eminently curious. As by our theory it follows that new
atolls will generally be formed in each new area of subsidence,
two weighty objections might have been raised,
namely, that atolls must be increasing indefinitely in number;
and secondly, that in old areas of subsidence each separate
atoll must be increasing indefinitely in thickness, if proofs
of their occasional destruction could not have been adduced.
Thus have we traced the history of these great rings of
coral-rock, from their first origin through their normal
changes, and through the occasional accidents of their
existence, to their death and final obliteration.
In my volume on "Coral Formations" I have published a
map, in which I have coloured all the atolls dark-blue, the
barrier-reefs pale-blue, and the fringing reefs red. These
latter reefs have been formed whilst the land has been
stationary, or, as appears from the frequent presence of
upraised organic remains, whilst it has been slowly rising:
atolls and barrier-reefs, on the other hand, have grown up
during the directly opposite movement of subsidence, which
movement must have been very gradual, and in the case of atolls
so vast in amount as to have buried every mountain-summit over
wide ocean-spaces. Now in this map we see that the reefs
tinted pale and dark-blue, which have been produced by the
same order of movement, as a general rule manifestly stand
near each other. Again we see, that the areas with the two
blue tints are of wide extent; and that they lie separate from
extensive lines of coast coloured red, both of which
circumstances might naturally have been inferred, on the theory
of the nature of the reefs having been governed by the nature
of the earth's movement. It deserves notice that in more
than one instance where single red and blue circles approach
near each other, I can show that there have been oscillations
of level; for in such cases the red or fringed circles consist
of atolls, originally by our theory formed during subsidence,
but subsequently upheaved; and on the other hand, some of
the pale-blue or encircled islands are composed of coral-rock,
which must have been uplifted to its present height before that
subsidence took place, during which the existing barrier-reefs
grew upwards.
Authors have noticed with surprise, that although atolls
are the commonest coral-structures throughout some enormous
oceanic tracts, they are entirely absent in other seas,
as in the West Indies: we can now at once perceive the
cause, for where there has not been subsidence, atolls cannot
have been formed; and in the case of the West Indies and
parts of the East Indies, these tracts are known to have been
rising within the recent period. The larger areas, coloured
red and blue, are all elongated; and between the two colours
there is a degree of rude alternation, as if the rising of one
had balanced the sinking of the other. Taking into consideration
the proofs of recent elevation both on the fringed
coasts and on some others (for instance, in South America)
where there are no reefs, we are led to conclude that the
great continents are for the most part rising areas: and from
the nature of the coral-reefs, that the central parts of the
great oceans are sinking areas. The East Indian archipelago,
the most broken land in the world, is in most parts an area
of elevation, but surrounded and penetrated, probably in
more lines than one, by narrow areas of subsidence.
I have marked with vermilion spots all the many known
active volcanos within the limits of this same map. Their
entire absence from every one of the great subsiding areas,
coloured either pale or dark blue, is most striking and not
less so is the coincidence of the chief volcanic chains with
the parts coloured red, which we are led to conclude have
either long remained stationary, or more generally have been
recently upraised. Although a few of the vermilion spots
occur within no great distance of single circles tinted blue,
yet not one single active volcano is situated within several
hundred miles of an archipelago, or even small group of
atolls. It is, therefore, a striking fact that in the Friendly
archipelago, which consists of a group of atolls upheaved
and since partially worn down, two volcanos, and perhaps
more, are historically known to have been in action. On the
other hand, although most of the islands in the Pacific which
are encircled by barrier-reefs, are of volcanic origin, often
with the remnants of craters still distinguishable, not one of
them is known to have ever been in eruption. Hence in these
cases it would appear, that volcanos burst forth into action
and become extinguished on the same spots, accordingly as
elevatory or subsiding movements prevail there. Numberless
facts could be adduced to prove that upraised organic remains
are common wherever there are active volcanos; but until it
could be shown that in areas of subsidence, volcanos were
either absent or inactive, the inference, however probable in
itself, that their distribution depended on the rising or
falling of the earth's surface, would have been hazardous. But
now, I think, we may freely admit this important deduction.
Taking a final view of the map, and bearing in mind the
statements made with respect to the upraised organic remains,
we must feel astonished at the vastness of the areas, which
have suffered changes in level either downwards or upwards,
within a period not geologically remote. It would appear
also, that the elevatory and subsiding movements follow
nearly the same laws. Throughout the spaces interspersed
with atolls, where not a single peak of high land has been
left above the level of the sea, the sinking must have been
immense in amount. The sinking, moreover, whether continuous,
or recurrent with intervals sufficiently long for the
corals again to bring up their living edifices to the surface,
must necessarily have been extremely slow. This conclusion is
probably the most important one which can be deduced from the
study of coral formations; -- and it is one which it is
difficult to imagine how otherwise could ever have been
arrived at. Nor can I quite pass over the probability of the
former existence of large archipelagoes of lofty islands,
where now only rings of coral-rock scarcely break the open
expanse of the sea, throwing some light on the distribution of
the inhabitants of the other high islands, now left standing
so immensely remote from each other in the midst of the
great oceans. The reef-constructing corals have indeed
reared and preserved wonderful memorials of the subterranean
oscillations of level; we see in each barrier-reef a
proof that the land has there subsided, and in each atoll a
monument over an island now lost. We may thus, like unto
a geologist who had lived his ten thousand years and kept a
record of the passing changes, gain some insight into the
great system by which the surface of this globe has been
broken up, and land and water interchanged.
[1] These Plants are described in the Annals of Nat. Hist.,
vol. i., 1838, p. 337.
[2] Holman's Travels, vol. iv. p. 378.
[3] Kotzebue's First Voyage, vol. iii. p. 155.
[4] The thirteen species belong to the following orders: -- In
the Coleoptera, a minute Elater; Orthoptera, a Gryllus and a
Blatta; Hemiptera, one species; Homoptera, two; Neuroptera a
Chrysopa; Hymenoptera, two ants; Lepidoptera nocturna, a
Diopaea, and a Pterophorus (?); Diptera, two species.
[5] Kotzebue's First Voyage, vol. iii. p. 222.
[6] The large claws or pincers of some of these crabs are most
beautifully adapted, when drawn back, to form an operculum to
the shell, nearly as perfect as the proper one originally
belonging to the molluscous animal. I was assured, and as far as
my observations went I found it so, that certain species of the
hermit-crab always use certain species of shells.
[7] Some natives carried by Kotzebue to Kamtschatka collected
stones to take back to their country.
[8] See Proceedings of Zoological Society, 1832, p. 17.
[9] Tyerman and Bennett. Voyage, etc. vol. ii. p. 33.
[10] I exclude, of course, some soil which has been imported
here in vessels from Malacca and Java, and likewise, some small
fragments of pumice, drifted here by the waves. The one block of
greenstone, moreover, on the northern island must be excepted.
[11] These were first read before the Geological Society in May,
1837, and have since been developed in a separate volume on the
"Structure and Distribution of Coral Reefs."
[12] It is remarkable that Mr. Lyell, even in the first edition
of his "Principles of Geology," inferred that the amount of
subsidence in the Pacific must have exceeded that of elevation,
from the area of land being very small relatively to the agents
there tending to form it, namely, the growth of coral and
volcanic action.
[13] It has been highly satisfactory to me to find the following
passage in a pamphlet by Mr. Couthouy, one of the naturalists in
the great Antarctic Expedition of the United States: -- "Having
personally examined a large number of coral-islands and resided
eight months among the volcanic class having shore and partially
encircling reefs. I may be permitted to state that my own
observations have impressed a conviction of the correctness of
the theory of Mr. Darwin." -- The naturalists, however, of this
expedition differ with me on some points respecting coral
formations.
CHAPTER XXI
MAURITIUS TO ENGLAND
Mauritius, beautiful appearance of -- Great crateriform ring of
Mountains -- Hindoos -- St. Helena -- History of the changes in
the Vegetation -- Cause of the extinction of Land-shells --
Ascension -- Variation in the imported Rats -- Volcanic Bombs --
Beds of Infusoria -- Bahia -- Brazil -- Splendour of Tropical
Scenery -- Pernambuco -- Singular Reef -- Slavery -- Return to
England -- Retrospect on our Voyage.
APRIL 29th. -- In the morning we passed round the
northern end of Mauritius, or the Isle of France.
From this point of view the aspect of the island
equalled the expectations raised by the many well-known
descriptions of its beautiful scenery. The sloping plain of
the Pamplemousses, interspersed with houses, and coloured
by the large fields of sugar-cane of a bright green, composed
the foreground. The brilliancy of the green was the more
remarkable because it is a colour which generally is conspicuous
only from a very short distance. Towards the centre
of the island groups of wooded mountains rose out of
this highly cultivated plain; their summits, as so commonly
happens with ancient volcanic rocks, being jagged into the
sharpest points. Masses of white clouds were collected
around these pinnacles, as if for the sake of pleasing the
stranger's eye. The whole island, with its sloping border
and central mountains, was adorned with an air of perfect
elegance: the scenery, if I may use such an expression, appeared
to the sight harmonious.
I spent the greater part of the next day in walking about
the town and visiting different people. The town is of
considerable size, and is said to contain 20,000 inhabitants;
the streets are very clean and regular. Although the island has
been so many years under the English Government, the general
character of the place is quite French: Englishmen
speak to their servants in French, and the shops are all
French; indeed, I should think that Calais or Boulogne was
much more Anglified. There is a very pretty little theatre,
in which operas are excellently performed. We were also
surprised at seeing large booksellers' shops, with well-stored
shelves; -- music and reading bespeak our approach to the
old world of civilization; for in truth both Australia and
America are new worlds.
The various races of men walking in the streets afford the
most interesting spectacle in Port Louis. Convicts from
India are banished here for life; at present there are about
800, and they are employed in various public works. Before
seeing these people, I had no idea that the inhabitants of
India were such noble-looking figures. Their skin is extremely
dark, and many of the older men had large mustaches
and beards of a snow-white colour; this, together with
the fire of their expression, gave them quite an imposing
aspect. The greater number had been banished for murder
and the worst crimes; others for causes which can scarcely
be considered as moral faults, such as for not obeying, from
superstitious motives, the English laws. These men are
generally quiet and well-conducted; from their outward
conduct, their cleanliness, and faithful observance of their
strange religious rites, it was impossible to look at them
with the same eyes as on our wretched convicts in New
South Wales.
May 1st. -- Sunday. I took a quiet walk along the sea-coast
to the north of the town. The plain in this part is quite
uncultivated; it consists of a field of black lava, smoothed
over with coarse grass and bushes, the latter being chiefly
Mimosas. The scenery may be described as intermediate in
character between that of the Galapagos and of Tahiti; but
this will convey a definite idea to very few persons. It is a
very pleasant country, but it has not the charms of Tahiti, or
the grandeur of Brazil. The next day I ascended La Pouce,
a mountain so called from a thumb-like projection, which
rises close behind the town to a height of 2,600 feet. The
centre of the island consists of a great platform, surrounded
by old broken basaltic mountains, with their strata dipping
seawards. The central platform, formed of comparatively
recent streams of lava, is of an oval shape, thirteen
geographical miles across, in the line of its shorter axis. The
exterior bounding mountains come into that class of structures
called Craters of Elevation, which are supposed to have
been formed not like ordinary craters, but by a great and
sudden upheaval. There appears to me to be insuperable
objections to this view: on the other hand, I can hardly
believe, in this and in some other cases, that these marginal
crateriform mountains are merely the basal remnants of
immense volcanos, of which the summits either have been
blown off, or swallowed up in subterranean abysses.
From our elevated position we enjoyed an excellent view over the
island. The country on this side appears pretty well cultivated,
being divided into fields and studded with farm-houses.
I was, however, assured that of the whole land, not
more than half is yet in a productive state; if such be the
case, considering the present large export of sugar, this
island, at some future period when thickly peopled, will be
of great value. Since England has taken possession of it, a
period of only twenty-five years, the export of sugar is said
to have increased seventy-five fold. One great cause of its
prosperity is the excellent state of the roads. In the
neighbouring Isle of Bourbon, which remains under the French
government, the roads are still in the same miserable state
as they were here only a few years ago. Although the
French residents must have largely profited by the increased
prosperity of their island, yet the English government is far
from popular.
3rd. -- In the evening Captain Lloyd, the Surveyor-general,
so well known from his examination of the Isthmus of Panama,
invited Mr. Stokes and myself to his country-house,
which is situated on the edge of Wilheim Plains, and about
six miles from the Port. We stayed at this delightful place
two days; standing nearly 800 feet above the sea, the air was
cool and fresh, and on every side there were delightful walks.
Close by, a grand ravine has been worn to a depth of about
500 feet through the slightly inclined streams of lava, which
have flowed from the central platform.
5th. -- Captain Lloyd took us to the Riviere Noire, which is
several miles to the southward, that I might examine some
rocks of elevated coral. We passed through pleasant gardens,
and fine fields of sugar-cane growing amidst huge
blocks of lava. The roads were bordered by hedges of
Mimosa, and near many of the houses there were avenues
of the mango. Some of the views, where the peaked hills
and the cultivated farms were seen together, were exceedingly
picturesque; and we were constantly tempted to
exclaim, "How pleasant it would be to pass one's life in
such quiet abodes!" Captain Lloyd possessed an elephant,
and he sent it half way with us, that we might enjoy a ride
in true Indian fashion. The circumstance which surprised
me most was its quite noiseless step. This elephant
is the only one at present on the island; but it is said others
will be sent for.
May 9th. -- We sailed from Port Louis, and, calling at the
Cape of Good Hope, on the 8th of July, we arrived off St.
Helena. This island, the forbidding aspect of which has
been so often described, rises abruptly like a huge black
castle from the ocean. Near the town, as if to complete
nature's defence, small forts and guns fill up every gap in
the rugged rocks. The town runs up a flat and narrow
valley; the houses look respectable, and are interspersed
with a very few green trees. When approaching the anchorage
there was one striking view: an irregular castle perched
on the summit of a lofty hill, and surrounded by a few scattered
fir-trees, boldly projected against the sky.
The next day I obtained lodgings within a stone's throw
of Napoleon's tomb; [1] it was a capital central situation,
whence I could make excursions in every direction. During
the four days I stayed here, I wandered over the island from
morning to night, and examined its geological history. My
lodgings were situated at a height of about 2000 feet; here
the weather was cold and boisterous, with constant showers
of rain; and every now and then the whole scene was veiled
in thick clouds.
Near the coast the rough lava is quite bare: in the central
and higher parts, feldspathic rocks by their decomposition
have produced a clayey soil, which, where not covered by
vegetation, is stained in broad bands of many bright colours.
At this season, the land moistened by constant showers,
produces a singularly bright green pasture, which lower and
lower down, gradually fades away and at last disappears. In
latitude 16 degs., and at the trifling elevation of 1500 feet,
it is surprising to behold a vegetation possessing a character
decidedly British. The hills are crowned with irregular
plantations of Scotch firs; and the sloping banks are thickly
scattered over with thickets of gorse, covered with its bright
yellow flowers. Weeping-willows are common on the banks
of the rivulets, and the hedges are made of the blackberry,
producing its well-known fruit. When we consider that the
number of plants now found on the island is 746, and that
out of these fifty-two alone are indigenous species, the rest
having been imported, and most of them from England,
we see the reason of the British character of the vegetation.
Many of these English plants appear to flourish better than
in their native country; some also from the opposite quarter
of Australia succeed remarkably well. The many imported
species must have destroyed some of the native kinds; and
it is only on the highest and steepest ridges that the
indigenous Flora is now predominant.
The English, or rather Welsh character of the scenery, is
kept up by the numerous cottages and small white houses;
some buried at the bottom of the deepest valleys, and others
mounted on the crests of the lofty hills. Some of the views
are striking, for instance that from near Sir W. Doveton's
house, where the bold peak called Lot is seen over a dark
wood of firs, the whole being backed by the red water-worn
mountains of the southern coast. On viewing the island
from an eminence, the first circumstance which strikes one,
is the number of the roads and forts: the labour bestowed
on the public works, if one forgets its character as a prison,
seems out of all proportion to its extent or value. There
is so little level or useful land, that it seems surprising how
so many people, about 5000, can subsist here. The lower
orders, or the emancipated slaves, are I believe extremely
poor: they complain of the want of work. From the reduction
in the number of public servants owing to the island
having been given up by the East Indian Company, and the
consequent emigration of many of the richer people, the
poverty probably will increase. The chief food of the working
class is rice with a little salt meat; as neither of these
articles are the products of the island, but must be purchased
with money, the low wages tell heavily on the poor people.
Now that the people are blessed with freedom, a right which
I believe they value fully, it seems probable that their numbers
will quickly increase: if so, what is to become of the
little state of St. Helena?
My guide was an elderly man, who had been a goatherd
when a boy, and knew every step amongst the rocks. He
was of a race many times crossed, and although with a
dusky skin, he had not the disagreeable expression of a
mulatto. He was a very civil, quiet old man, and such
appears the character of the greater number of the lower
classes. It was strange to my ears to hear a man, nearly
white and respectably dressed, talking with indifference of
the times when he was a slave. With my companion, who
carried our dinners and a horn of water, which is quite
necessary, as all the water in the lower valleys is saline, I
every day took long walks.
Beneath the upper and central green circle, the wild valleys
are quite desolate and untenanted. Here, to the geologist,
there were scenes of high interest, showing successive
changes and complicated disturbances. According to my
views, St. Helena has existed as an island from a very
remote epoch: some obscure proofs, however, of the elevation
of the land are still extant. I believe that the central
and highest peaks form parts of the rim of a great crater,
the southern half of which has been entirely removed by the
waves of the sea: there is, moreover, an external wall of
black basaltic rocks, like the coast-mountains of Mauritius,
which are older than the central volcanic streams. On the
higher parts of the island, considerable numbers of a shell,
long thought to be a marine species occur imbedded in the soil.
It proved to be a Cochlogena, or land-shell of a very
peculiar form; [2] with it I found six other kinds; and in
another spot an eighth species. It is remarkable that none
of them are now found living. Their extinction has probably
been caused by the entire destruction of the woods, and
the consequent loss of food and shelter, which occurred
during the early part of the last century.
The history of the changes, which the elevated plains of
Longwood and Deadwood have undergone, as given in General
Beatson's account of the island, is extremely curious.
Both plains, it is said in former times were covered with
wood, and were therefore called the Great Wood. So late
as the year 1716 there were many trees, but in 1724 the old
trees had mostly fallen; and as goats and hogs had been
suffered to range about, all the young trees had been killed.
It appears also from the official records, that the trees were
unexpectedly, some years afterwards, succeeded by a wire
grass which spread over the whole surface. [3] General Beatson
adds that now this plain "is covered with fine sward, and
is become the finest piece of pasture on the island." The
extent of surface, probably covered by wood at a former
period, is estimated at no less than two thousand acres; at
the present day scarcely a single tree can be found there. It
is also said that in 1709 there were quantities of dead trees
in Sandy Bay; this place is now so utterly desert, that nothing
but so well attested an account could have made me believe
that they could ever have grown there. The fact, that the
goats and hogs destroyed all the young trees as they sprang
up, and that in the course of time the old ones, which were
safe from their attacks, perished from age, seems clearly
made out. Goats were introduced in the year 1502; eighty-six
years afterwards, in the time of Cavendish, it is known
that they were exceedingly numerous. More than a century
afterwards, in 1731, when the evil was complete and
irretrievable, an order was issued that all stray animals should
be destroyed. It is very interesting thus to find, that the
arrival of animals at St. Helena in 1501, did not change the
whole aspect of the island, until a period of two hundred
and twenty years had elapsed: for the goats were introduced
in 1502, and in 1724 it is said "the old trees had mostly
fallen." There can be little doubt that this great change in
the vegetation affected not only the land-shells, causing eight
species to become extinct, but likewise a multitude of insects.
St. Helena, situated so remote from any continent, in the
midst of a great ocean, and possessing a unique Flora, excites
our curiosity. The eight land-shells, though now extinct,
and one living Succinea, are peculiar species found nowhere
else. Mr. Cuming, however, informs me that an English
Helix is common here, its eggs no doubt having been imported
in some of the many introduced plants. Mr. Cuming
collected on the coast sixteen species of sea-shells, of which
seven, as far as he knows, are confined to this island. Birds
and insects, [4] as might have been expected, are very few in
number; indeed I believe all the birds have been introduced
within late years. Partridges and pheasants are tolerably
abundant; the island is much too English not to be subject
to strict game-laws. I was told of a more unjust sacrifice to
such ordinances than I ever heard of even in England. The
poor people formerly used to burn a plant, which grows on the
coast-rocks, and export the soda from its ashes; but a
peremptory order came out prohibiting this practice, and giving
as a reason that the partridges would have nowhere to build.
In my walks I passed more than once over the grassy plain
bounded by deep valleys, on which Longwood stands.
Viewed from a short distance, it appears like a respectable
gentleman's country-seat. In front there are a few cultivated
fields, and beyond them the smooth hill of coloured
rocks called the Flagstaff, and the rugged square black mass
of the Barn. On the whole the view was rather bleak and
uninteresting. The only inconvenience I suffered during my
walks was from the impetuous winds. One day I noticed
a curious circumstance; standing on the edge of a plain,
terminated by a great cliff of about a thousand feet in depth,
I saw at the distance of a few yards right to windward, some
tern, struggling against a very strong breeze, whilst, where
I stood, the air was quite calm. Approaching close to the
brink, where the current seemed to be deflected upwards
from the face of the cliff, I stretched out my arm, and
immediately felt the full force of the wind: an invisible
barrier, two yards in width, separated perfectly calm air
from a strong blast.
I so much enjoyed my rambles among the rocks and mountains
of St. Helena, that I felt almost sorry on the morning
of the 14th to descend to the town. Before noon I was on
board, and the Beagle made sail.
On the 19th of July we reached Ascension. Those who
have beheld a volcanic island, situated under an arid climate,
will at once be able to picture to themselves the appearance
of Ascension. They will imagine smooth conical hills of a
bright red colour, with their summits generally truncated,
rising separately out of a level surface of black rugged lava.
A principal mound in the centre of the island, seems the
father of the lesser cones. It is called Green Hill: its
name being taken from the faintest tinge of that colour,
which at this time of the year is barely perceptible from the
anchorage. To complete the desolate scene, the black rocks
on the coast are lashed by a wild and turbulent sea.
The settlement is near the beach; it consists of several
houses and barracks placed irregularly, but well built of
white freestone. The only inhabitants are marines, and some
negroes liberated from slave-ships, who are paid and victualled
by government. There is not a private person on the
island. Many of the marines appeared well contented with their
situation; they think it better to serve their one-and-twenty
years on shore, let it be what it may, than in a ship; in this
choice, if I were a marine, I should most heartily agree.
The next morning I ascended Green Hill, 2840 feet high,
and thence walked across the island to the windward point.
A good cart-road leads from the coast-settlement to the
houses, gardens, and fields, placed near the summit of the
central mountain. On the roadside there are milestones, and
likewise cisterns, where each thirsty passer-by can drink
some good water. Similar care is displayed in each part of the
establishment, and especially in the management of the
springs, so that a single drop of water may not be lost: indeed
the whole island may be compared to a huge ship kept
in first-rate order. I could not help, when admiring the
active industry, which had created such effects out of such
means, at the same time regretting that it had been wasted on
so poor and trifling an end. M. Lesson has remarked with
justice, that the English nation would have thought of making
the island of Ascension a productive spot, any other
people would have held it as a mere fortress in the ocean.
Near this coast nothing grows; further inland, an occasional
green castor-oil plant, and a few grasshoppers, true
friends of the desert, may be met with. Some grass is scattered
over the surface of the central elevated region, and the
whole much resembles the worse parts of the Welsh mountains.
But scanty as the pasture appears, about six hundred
sheep, many goats, a few cows and horses, all thrive well on
it. Of native animals, land-crabs and rats swarm in numbers.
Whether the rat is really indigenous, may well be doubted;
there are two varieties as described by Mr. Waterhouse;
one is of a black colour, with fine glossy fur, and
lives on the grassy summit, the other is brown-coloured and
less glossy, with longer hairs, and lives near the settlement
on the coast. Both these varieties are one-third smaller than
the common black rat (M. rattus); and they differ from it
both in the colour and character of their fur, but in no
other essential respect. I can hardly doubt that these rats
(like the common mouse, which has also run wild) have
been imported, and, as at the Galapagos, have varied from
the effect of the new conditions to which they have been
exposed: hence the variety on the summit of the island
differs from that on the coast. Of native birds there are
none; but the guinea-fowl, imported from the Cape de
Verd Islands, is abundant, and the common fowl has likewise
run wild. Some cats, which were originally turned out
to destroy the rats and mice, have increased, so as to become
a great plague. The island is entirely without trees,
in which, and in every other respect, it is very far inferior
to St. Helena.
One of my excursions took me towards the S. W. extremity
of the island. The day was clear and hot, and I saw the
island, not smiling with beauty, but staring with naked
hideousness. The lava streams are covered with hummocks, and
are rugged to a degree which, geologically speaking, is not
of easy explanation. The intervening spaces are concealed
with layers of pumice, ashes and volcanic tuff. Whilst passing
this end of the island at sea, I could not imagine what
the white patches were with which the whole plain was
mottled; I now found that they were seafowl, sleeping in such
full confidence, that even in midday a man could walk up
and seize hold of them. These birds were the only living
creatures I saw during the whole day. On the beach a great
surf, although the breeze was light, came tumbling over
the broken lava rocks.
The geology of this island is in many respects interesting.
In several places I noticed volcanic bombs, that is, masses of
lava which have been shot through the air whilst fluid, and
have consequently assumed a spherical or pear-shape. Not
only their external form, but, in several cases, their internal
structure shows in a very curious manner that they have revolved
in their aerial course. The internal structure of one
of these bombs, when broken, is represented very accurately
in the woodcut. The central part is coarsely cellular, the
cells decreasing in size towards the exterior; where there
is a shell-like case about the third of an inch in thickness,
of compact stone, which again is overlaid by the outside
crust of finely cellular lava. I think there can be little
doubt, first that the external crust cooled rapidly in the state
in which we now see it; secondly, that the still fluid lava
within, was packed by the centrifugal force, generated by
[picture]
the revolving of the bomb, against the external cooled
crust, and so produced the solid shell of stone; and lastly,
that the centrifugal force, by relieving the pressure in the
more central parts of the bomb, allowed the heated vapours
to expand their cells, thus forming the coarse cellular mass
of the centre.
A hill, formed of the older series of volcanic rocks, and
which has been incorrectly considered as the crater of a
volcano, is remarkable from its broad, slightly hollowed, and
circular summit having been filled up with many successive
layers of ashes and fine scoriae. These saucer-shaped layers
crop out on the margin, forming perfect rings of many different
colours, giving to the summit a most fantastic appearance;
one of these rings is white and broad, and resembles
a course round which horses have been exercised; hence the
hill has been called the Devil's Riding School. I brought away
specimens of one of the tufaceous layers of a pinkish colour and
it is a most extraordinary fact, that Professor Ehrenberg [5]
finds it almost wholly composed of matter which has been
organized: he detects in it some siliceous-shielded fresh-water
infusoria, and no less than twenty-five different kinds
of the siliceous tissue of plants, chiefly of grasses. From
the absence of all carbonaceous matter, Professor Ehrenberg
believes that these organic bodies have passed through the
volcanic fire, and have been erupted in the state in which
we now see them. The appearance of the layers induced me
to believe that they had been deposited under water, though
from the extreme dryness of the climate I was forced to imagine,
that torrents of rain had probably fallen during some
great eruption, and that thus a temporary lake had been
formed into which the ashes fell. But it may now be suspected
that the lake was not a temporary one. Anyhow, we
may feel sure, that at some former epoch the climate and
productions of Ascension were very different from what
they now are. Where on the face of the earth can we find
a spot, on which close investigation will not discover signs
of that endless cycle of change, to which this earth has been,
is, and will be subjected?
On leaving Ascension, we sailed for Bahia, on the coast
of Brazil, in order to complete the chronometrical measurement
of the world. We arrived there on August 1st, and
stayed four days, during which I took several long walks.
I was glad to find my enjoyment in tropical scenery had not
decreased from the want of novelty, even in the slightest
degree. The elements of the scenery are so simple, that they
are worth mentioning, as a proof on what trifling circumstances
exquisite natural beauty depends.
The country may be described as a level plain of about
three hundred feet in elevation, which in all parts has been
worn into flat-bottomed valleys. This structure is remarkable
in a granitic land, but is nearly universal in all those
softer formations of which plains are usually composed.
The whole surface is covered by various kinds of stately
trees, interspersed with patches of cultivated ground, out
of which houses, convents, and chapels arise. It must be
remembered that within the tropics, the wild luxuriance of
nature is not lost even in the vicinity of large cities: for
the natural vegetation of the hedges and hill-sides overpowers
in picturesque effect the artificial labour of man.
Hence, there are only a few spots where the bright red
soil affords a strong contrast with the universal clothing
of green. From the edges of the plain there are distant
views either of the ocean, or of the great Bay with its
low-wooded shores, and on which numerous boats and canoes
show their white sails. Excepting from these points, the
scene is extremely limited; following the level pathways,
on each hand, only glimpses into the wooded valleys below
can be obtained. The houses I may add, and especially the
sacred edifices, are built in a peculiar and rather fantastic
style of architecture. They are all whitewashed; so that
when illumined by the brilliant sun of midday, and as seen
against the pale blue sky of the horizon, they stand out more
like shadows than real buildings.
Such are the elements of the scenery, but it is a hopeless
attempt to paint the general effect. Learned naturalists
describe these scenes of the tropics by naming a multitude of
objects, and mentioning some characteristic feature of each.
To a learned traveller this possibly may communicate some
definite ideas: but who else from seeing a plant in an herbarium
can imagine its appearance when growing in its native
soil? Who from seeing choice plants in a hothouse, can
magnify some into the dimensions of forest trees, and crowd
others into an entangled jungle? Who when examining in
the cabinet of the entomologist the gay exotic butterflies,
and singular cicadas, will associate with these lifeless
objects, the ceaseless harsh music of the latter, and the
lazy flight of the former, -- the sure accompaniments of the
still, glowing noon-day of the tropics? It is when the sun has
attained its greatest height, that such scenes should be
viewed: then the dense splendid foliage of the mango hides
the ground with its darkest shade, whilst the upper branches
are rendered from the profusion of light of the most brilliant
green. In the temperate zones the case is different -- the
vegetation there is not so dark or so rich, and hence the
rays of the declining sun, tinged of a red, purple, or bright
yellow color, add most to the beauties of those climes.
When quietly walking along the shady pathways, and admiring
each successive view, I wished to find language to
express my ideas. Epithet after epithet was found too weak
to convey to those who have not visited the intertropical
regions, the sensation of delight which the mind experiences.
I have said that the plants in a hothouse fail to communicate
a just idea of the vegetation, yet I must recur to it. The land
is one great wild, untidy, luxuriant hothouse, made by
Nature for herself, but taken possession of by man, who has
studded it with gay houses and formal gardens. How great
would be the desire in every admirer of nature to behold,
if such were possible, the scenery of another planet! yet
to every person in Europe, it may be truly said, that at
the distance of only a few degrees from his native soil, the
glories of another world are opened to him. In my last
walk I stopped again and again to gaze on these beauties, and
endeavoured to fix in my mind for ever, an impression which
at the time I knew sooner or later must fail. The form of the
orange-tree, the cocoa-nut, the palm, the mango, the tree-fern,
the banana, will remain clear and separate; but the
thousand beauties which unite these into one perfect scene
must fade away: yet they will leave, like a tale heard in
childhood, a picture full of indistinct, but most beautiful
figures.
August 6th. -- In the afternoon we stood out to sea, with
the intention of making a direct course to the Cape de Verd
Islands. Unfavourable winds, however, delayed us, and on
the 12th we ran into Pernambuco, -- a large city on the
coast of Brazil, in latitude 8 degs. south. We anchored outside
the reef; but in a short time a pilot came on board and
took us into the inner harbour, where we lay close to the
town.
Pernambuco is built on some narrow and low sand-banks,
which are separated from each other by shoal channels of
salt water. The three parts of the town are connected together
by two long bridges built on wooden piles. The town is in
all parts disgusting, the streets being narrow, ill-paved,
and filthy; the houses, tall and gloomy. The season
of heavy rains had hardly come to an end, and hence the
surrounding country, which is scarcely raised above the
level of the sea, was flooded with water; and I failed in
all my attempts to take walks.
The flat swampy land on which Pernambuco stands is surrounded,
at the distance of a few miles, by a semicircle of
low hills, or rather by the edge of a country elevated perhaps
two hundred feet above the sea. The old city of
Olinda stands on one extremity of this range. One day I
took a canoe, and proceeded up one of the channels to visit
it; I found the old town from its situation both sweeter and
cleaner than that of Pernambuco. I must here commemorate
what happened for the first time during our nearly five
years' wandering, namely, having met with a want of politeness.
I was refused in a sullen manner at two different
houses, and obtained with difficulty from a third, permission
to pass through their gardens to an uncultivated hill,
for the purpose of viewing the country. I feel glad that
this happened in the land of the Brazilians, for I bear
them no good will -- a land also of slavery, and therefore
of moral debasement. A Spaniard would have felt ashamed
at the very thought of refusing such a request, or of
behaving to a stranger with rudeness. The channel by which
we went to and returned from Olinda, was bordered on each
side by mangroves, which sprang like a miniature forest out
of the greasy mud-banks. The bright green colour of these
bushes always reminded me of the rank grass in a church-yard:
both are nourished by putrid exhalations; the one speaks of
death past, and the other too often of death to come.
The most curious object which I saw in this neighbourhood,
was the reef that forms the harbour. I doubt whether
in the whole world any other natural structure has so artificial
an appearance. [6] It runs for a length of several miles in
an absolutely straight line, parallel to, and not far distant
from, the shore. It varies in width from thirty to sixty
yards, and its surface is level and smooth; it is composed of
obscurely stratified hard sandstone. At high water the waves
break over it; at low water its summit is left dry, and it
might then be mistaken for a breakwater erected by Cyclopean
workmen. On this coast the currents of the sea tend
to throw up in front of the land, long spits and bars of
loose sand, and on one of these, part of the town of Pernambuco
stands. In former times a long spit of this nature
seems to have become consolidated by the percolation of
calcareous matter, and afterwards to have been gradually
upheaved; the outer and loose parts during this process having
been worn away by the action of the sea, and the solid
nucleus left as we now see it. Although night and day the
waves of the open Atlantic, turbid with sediment, are
driven against the steep outside edges of this wall of stone,
yet the oldest pilots know of no tradition of any change in its
appearance. This durability is much the most curious fact
in its history: it is due to a tough layer, a few inches thick,
of calcareous matter, wholly formed by the successive
growth and death of the small shells of Serpulae, together
with some few barnacles and nulliporae. These nulliporae,
which are hard, very simply-organized sea-plants, play an
analogous and important part in protecting the upper surfaces
of coral-reefs, behind and within the breakers, where
the true corals, during the outward growth of the mass,
become killed by exposure to the sun and air. These
insignificant organic beings, especially the Serpulae, have done
good service to the people of Pernambuco; for without their
protective aid the bar of sandstone would inevitably have
been long ago worn away and without the bar, there would
have been no harbour.
On the 19th of August we finally left the shores of Brazil.
I thank God, I shall never again visit a slave-country. To
this day, if I hear a distant scream, it recalls with painful
vividness my feelings, when passing a house near Pernambuco,
I heard the most pitiable moans, and could not but
suspect that some poor slave was being tortured, yet knew
that I was as powerless as a child even to remonstrate. I
suspected that these moans were from a tortured slave, for I
was told that this was the case in another instance. Near
Rio de Janeiro I lived opposite to an old lady, who kept
screws to crush the fingers of her female slaves. I have
stayed in a house where a young household mulatto, daily
and hourly, was reviled, beaten, and persecuted enough to
break the spirit of the lowest animal. I have seen a little
boy, six or seven years old, struck thrice with a horse-whip
(before I could interfere) on his naked head, for having
handed me a glass of water not quite clean; I saw his
father tremble at a mere glance from his master's eye.
These latter cruelties were witnessed by me in a Spanish
colony, in which it has always been said, that slaves are
better treated than by the Portuguese, English, or other
European nations. I have seen at Rio de Janeiro a powerful
negro afraid to ward off a blow directed, as he thought, at his
face. I was present when a kind-hearted man was on the
point of separating forever the men, women, and little
children of a large number of families who had long lived
together. I will not even allude to the many heart-sickening
atrocities which I authentically heard of; -- nor would I have
mentioned the above revolting details, had I not met with
several people, so blinded by the constitutional gaiety of the
negro as to speak of slavery as a tolerable evil. Such people
have generally visited at the houses of the upper classes, where
the domestic slaves are usually well treated, and they have
not, like myself, lived amongst the lower classes. Such
inquirers will ask slaves about their condition; they forget
that the slave must indeed be dull, who does not calculate
on the chance of his answer reaching his master's ears.
It is argued that self-interest will prevent excessive cruelty;
as if self-interest protected our domestic animals, which
are far less likely than degraded slaves, to stir up the rage
of their savage masters. It is an argument long since protested
against with noble feeling, and strikingly exemplified,
by the ever-illustrious Humboldt. It is often attempted to
palliate slavery by comparing the state of slaves with our
poorer countrymen: if the misery of our poor be caused
not by the laws of nature, but by our institutions, great is
our sin; but how this bears on slavery, I cannot see; as well
might the use of the thumb-screw be defended in one
land, by showing that men in another land suffered from
some dreadful disease. Those who look tenderly at the slave
owner, and with a cold heart at the slave, never seem to put
themselves into the position of the latter; what a cheerless
prospect, with not even a hope of change! picture to yourself
the chance, ever hanging over you, of your wife and
your little children -- those objects which nature urges even
the slave to call his own -- being torn from you and sold
like beasts to the first bidder! And these deeds are done
and palliated by men, who profess to love their neighbours
as themselves, who believe in God, and pray that his Will be
done on earth! It makes one's blood boil, yet heart tremble,
to think that we Englishmen and our American descendants,
with their boastful cry of liberty, have been and are so
guilty: but it is a consolation to reflect, that we at least
have made a greater sacrifice, than ever made by any nation,
to expiate our sin.
On the last day of August we anchored for the second time
at Porto Praya in the Cape de Verd archipelago; thence we
proceeded to the Azores, where we stayed six days. On the
2nd of October we made the shore, of England; and at Falmouth
I left the Beagle, having lived on board the good little
vessel nearly five years.
Our Voyage having come to an end, I will take a short
retrospect of the advantages and disadvantages, the pains
and pleasures, of our circumnavigation of the world. If a
person asked my advice, before undertaking a long voyage,
my answer would depend upon his possessing a decided taste
for some branch of knowledge, which could by this means be
advanced. No doubt it is a high satisfaction to behold various
countries and the many races of mankind, but the pleasures
gained at the time do not counterbalance the evils. It is
necessary to look forward to a harvest, however distant
that may be, when some fruit will be reaped, some good
effected.
Many of the losses which must be experienced are obvious;
such as that of the society of every old friend, and of the
sight of those places with which every dearest remembrance
is so intimately connected. These losses, however, are at
the time partly relieved by the exhaustless delight of
anticipating the long wished-for day of return. If, as poets
say, life is a dream, I am sure in a voyage these are the
visions which best serve to pass away the long night. Other
losses, although not at first felt, tell heavily after a period:
these are the want of room, of seclusion, of rest; the jading
feeling of constant hurry; the privation of small luxuries, the
loss of domestic society and even of music and the other
pleasures of imagination. When such trifles are mentioned, it is
evident that the real grievances, excepting from accidents, of
a sea-life are at an end. The short space of sixty years has
made an astonishing difference in the facility of distant
navigation. Even in the time of Cook, a man who left
his fireside for such expeditions underwent severe privations.
A yacht now, with every luxury of life, can circumnavigate
the globe. Besides the vast improvements in ships and
naval resources, the whole western shores of America are
thrown open, and Australia has become the capital of a
rising continent. How different are the circumstances to a
man shipwrecked at the present day in the Pacific, to what
they were in the time of Cook! Since his voyage a hemisphere
has been added to the civilized world.
If a person suffer much from sea-sickness, let him weigh
it heavily in the balance. I speak from experience: it is no
trifling evil, cured in a week. If, on the other hand, he take
pleasure in naval tactics, he will assuredly have full scope
for his taste. But it must be borne in mind, how large a
proportion of the time, during a long voyage, is spent on
the water, as compared with the days in harbour. And what
are the boasted glories of the illimitable ocean. A tedious
waste, a desert of water, as the Arabian calls it. No doubt
there are some delightful scenes. A moonlight night, with
the clear heavens and the dark glittering sea, and the white
sails filled by the soft air of a gently blowing trade-wind, a
dead calm, with the heaving surface polished like a mirror,
and all still except the occasional flapping of the canvas.
It is well once to behold a squall with its rising arch and
coming fury, or the heavy gale of wind and mountainous
waves. I confess, however, my imagination had painted
something more grand, more terrific in the full-grown storm.
It is an incomparably finer spectacle when beheld on shore,
where the waving trees, the wild flight of the birds, the
dark shadows and bright lights, the rushing of the torrents
all proclaim the strife of the unloosed elements. At sea
the albatross and little petrel fly as if the storm were their
proper sphere, the water rises and sinks as if fulfilling its
usual task, the ship alone and its inhabitants seem the objects
of wrath. On a forlorn and weather-beaten coast, the scene
is indeed different, but the feelings partake more of horror
than of wild delight.
Let us now look at the brighter side of the past time. The
pleasure derived from beholding the scenery and the general
aspect of the various countries we have visited, has decidedly
been the most constant and highest source of enjoyment. It
is probable that the picturesque beauty of many parts of
Europe exceeds anything which we beheld. But there is a
growing pleasure in comparing the character of the scenery
in different countries, which to a certain degree is distinct
from merely admiring its beauty. It depends chiefly on an
acquaintance with the individual parts of each view. I am
strongly induced to believe that as in music, the person who
understands every note will, if he also possesses a proper
taste, more thoroughly enjoy the whole, so he who examines
each part of a fine view, may also thoroughly comprehend
the full and combined effect. Hence, a traveller should be
a botanist, for in all views plants form the chief
embellishment. Group masses of naked rock, even in the wildest
forms, and they may for a time afford a sublime spectacle,
but they will soon grow monotonous. Paint them with bright
and varied colours, as in Northern Chile, they will become
fantastic; clothe them with vegetation, they must form a
decent, if not a beautiful picture.
When I say that the scenery of parts of Europe is probably
superior to anything which we beheld, I except, as a class by
itself, that of the intertropical zones. The two classes cannot
be compared together; but I have already often enlarged on
the grandeur of those regions. As the force of impressions
generally depends on preconceived ideas, I may add, that
mine were taken from the vivid descriptions in the Personal
Narrative of Humboldt, which far exceed in merit anything
else which I have read. Yet with these high-wrought ideas,
my feelings were far from partaking of a tinge of disappointment
on my first and final landing on the shores of Brazil.
Among the scenes which are deeply impressed on my mind,
none exceed in sublimity the primeval forests undefaced by
the hand of man; whether those of Brazil, where the powers
of Life are predominant, or those of Tierra del Fuego,
where Death and decay prevail. Both are temples filled with
the varied productions of the God of Nature: -- no one can
stand in these solitudes unmoved, and not feel that there is
more in man than the mere breath of his body. In calling
up images of the past, I find that the plains of Patagonia
frequently cross before my eyes; yet these plains are pronounced
by all wretched and useless. They can be described
only by negative characters; without habitations, without
water, without trees, without mountains, they support merely
a few dwarf plants. Why, then, and the case is not peculiar
to myself, have these arid wastes taken so firm a hold on
my memory? Why have not the still more level, the greener
and more fertile Pampas, which are serviceable to mankind,
produced an equal impression? I can scarcely analyze these
feelings: but it must be partly owing to the free scope given
to the imagination. The plains of Patagonia are boundless,
for they are scarcely passable, and hence unknown: they
bear the stamp of having lasted, as they are now, for ages,
and there appears no limit to their duration through future
time. If, as the ancients supposed, the flat earth was
surrounded by an impassable breadth of water, or by deserts
heated to an intolerable excess, who would not look at these
last boundaries to man's knowledge with deep but ill-defined
sensations?
Lastly, of natural scenery, the views from lofty mountains,
through certainly in one sense not beautiful, are very
memorable. When looking down from the highest crest of the
Cordillera, the mind, undisturbed by minute details, was
filled with the stupendous dimensions of the surrounding masses.
Of individual objects, perhaps nothing is more certain to
create astonishment than the first sight in his native haunt of
a barbarian -- of man in his lowest and most savage state.
One's mind hurries back over past centuries, and then asks,
could our progenitors have been men like these? -- men,
whose very signs and expressions are less intelligible to us
than those of the domesticated animals; men, who do not
possess the instinct of those animals, nor yet appear to boast
of human reason, or at least of arts consequent on that
reason. I do not believe it is possible to describe or paint
the difference between savage and civilized man. It is
the difference between a wild and tame animal: and part
of the interest in beholding a savage, is the same which
would lead every one to desire to see the lion in his desert,
the tiger tearing his prey in the jungle, or the rhinoceros
wandering over the wild plains of Africa.
Among the other most remarkable spectacles which we
have beheld, may be ranked, the Southern Cross, the cloud
of Magellan, and the other constellations of the southern
hemisphere -- the water-spout -- the glacier leading its blue
stream of ice, overhanging the sea in a bold precipice -- a
lagoon-island raised by the reef-building corals -- an active
volcano -- and the overwhelming effects of a violent earthquake.
These latter phenomena, perhaps, possess for me a
peculiar interest, from their intimate connection with the
geological structure of the world. The earthquake, however,
must be to every one a most impressive event: the earth,
considered from our earliest childhood as the type of solidity,
has oscillated like a thin crust beneath our feet; and
in seeing the laboured works of man in a moment overthrown,
we feel the insignificance of his boasted power.
It has been said, that the love of the chase is an inherent
delight in man -- a relic of an instinctive passion. If so, I
am sure the pleasure of living in the open air, with the sky
for a roof and the ground for a table, is part of the same
feeling, it is the savage returning to his wild and native
habits. I always look back to our boat cruises, and my land
journeys, when through unfrequented countries, with an extreme
delight, which no scenes of civilization could have
created. I do not doubt that every traveller must remember
the glowing sense of happiness which he experienced, when
he first breathed in a foreign clime, where the civilized man
had seldom or never trod.
There are several other sources of enjoyment in a long
voyage, which are of a more reasonable nature. The map
of the world ceases to be a blank; it becomes a picture full
of the most varied and animated figures. Each part assumes
its proper dimensions: continents are not looked at in the
light of islands, or islands considered as mere specks, which
are, in truth, larger than many kingdoms of Europe. Africa,
or North and South America, are well-sounding names, and
easily pronounced; but it is not until having sailed for
weeks along small portions of their shores, that one is
thoroughly convinced what vast spaces on our immense world
these names imply.
From seeing the present state, it is impossible not to look
forward with high expectations to the future progress of
nearly an entire hemisphere. The march of improvement,
consequent on the introduction of Christianity throughout
the South Sea, probably stands by itself in the records of
history. It is the more striking when we remember that only
sixty years since, Cook, whose excellent judgment none will
dispute, could foresee no prospect of a change. Yet these
changes have now been effected by the philanthropic spirit
of the British nation.
In the same quarter of the globe Australia is rising, or
indeed may be said to have risen, into a grand centre of
civilization, which, at some not very remote period, will rule
as empress over the southern hemisphere. It is impossible
for an Englishman to behold these distant colonies, without
a high pride and satisfaction. To hoist the British flag,
seems to draw with it as a certain consequence, wealth,
prosperity, and civilization.
In conclusion, it appears to me that nothing can be more
improving to a young naturalist, than a journey in distant
countries. It both sharpens, and partly allays that want and
craving, which, as Sir J. Herschel remarks, a man experiences
although every corporeal sense be fully satisfied. The
excitement from the novelty of objects, and the chance of
success, stimulate him to increased activity. Moreover, as a
number of isolated facts soon become uninteresting, the
habit of comparison leads to generalization. On the other
hand, as the traveller stays but a short time in each place,
his descriptions must generally consist of mere sketches,
instead of detailed observations. Hence arises, as I have found
to my cost, a constant tendency to fill up the wide gaps of
knowledge, by inaccurate and superficial hypotheses.
But I have too deeply enjoyed the voyage, not to recommend
any naturalist, although he must not expect to be so
fortunate in his companions as I have been, to take all
chances, and to start, on travels by land if possible, if
otherwise, on a long voyage. He may feel assured, he will meet
with no difficulties or dangers, excepting in rare cases, nearly
so bad as he beforehand anticipates. In a moral point of
view, the effect ought to be, to teach him good-humoured
patience, freedom from selfishness, the habit of acting for
himself, and of making the best of every occurrence. In
short, he ought to partake of the characteristic qualities of
most sailors. Travelling ought also to teach him distrust; but
at the same time he will discover, how many truly kind-hearted
people there are, with whom he never before had, or ever again
will have any further communication, who yet are ready to offer
him the most disinterested assistance.
[1] After the volumes of eloquence which have poured forth on
this subject, it is dangerous even to mention the tomb. A
modern traveller, in twelve lines, burdens the poor little
island with the following titles, -- it is a grave, tomb,
pyramid, cemetery, sepulchre, catacomb, sarcophagus, minaret,
and mausoleum!
[2] It deserves notice, that all the many specimens of this
shell found by me in one spot, differ as a marked variety,
from another set of specimens procured from a different spot.
[3] Beatson's St. Helena. Introductory chapter, p. 4.
[4] Among these few insects, I was surprised to find a small
Aphodius (nov. spec.) and an Oryctes, both extremely numerous
under dung. When the island was discovered it certainly
possessed no quadruped, excepting perhaps a mouse: it becomes,
therefore, a difficult point to ascertain, whether these
stercovorous insects have since been imported by accident, or if
aborigines, on what food they formerly subsisted. On the banks
of the Plata, where, from the vast number of cattle and horses,
the fine plains of turf are richly manured, it is vain to seek
the many kinds of dung-feeding beetles, which occur so
abundantly in Europe. I observed only an Oryctes (the insects of
this genus in Europe generally feed on decayed vegetable matter)
and two species of Phanaeus, common in such situations. On the
opposite side of the Cordillera in Chiloe, another species of
Phanaeus is exceedingly abundant, and it buries the dung of the
cattle in large earthen balls beneath the ground. There is
reason to believe that the genus Phanaeus, before the
introduction of cattle, acted as scavengers to man. In Europe,
beetles, which find support in the matter which has already
contributed towards the life of other and larger animals, are so
numerous that there must be considerably more than one hundred
different species. Considering this, and observing what a
quantity of food of this kind is lost on the plains of La Plata,
I imagined I saw an instance where man had disturbed that chain,
by which so many animals are linked together in their native
country. In Van Diemen's Land, however, I found four species of
Onthophagus, two of Aphodius, and one of a third genus, very
abundantly under the dung of cows; yet these latter animals had
been then introduced only thirty-three years. Previous to that
time the kangaroo and some other small animals were the only
quadrupeds; and their dung is of a very different quality from
that of their successors introduced by man. In England the
greater number of stercovorous beetles are confined in their
appetites; that is, they do not depend indifferently on any
quadruped for the means of subsistence. The change, therefore,
in habits which must have taken place in Van Diemen's Land is
highly remarkable. I am indebted to the Rev. F. W. Hope, who, I
hope, will permit me to call him my master in Entomology, for
giving me the names of the foregoing insects.
[5] Monats. der Konig. Akad. d. Wiss. zu Berlin. Vom
April, 1845.
[6] I have described this Bar in detail, in the Lond. and
Edin. Phil. Mag., vol. xix. (1841), p. 257.
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