Strait of Magellan--Port Famine--Geology--Deep water
in channels--Erratic boulders--Climate--Limit of fruit
trees--Mean temperature--Luxuriant forests--Rigour of antarctic
islands--Contrast with the north--Snow-line, great flexure
of--Glaciers--Icebergs transport fragments of rock--Glacier
in low latitude--Absence of erratic blocks in intertropical
regions--Glaciers and tropical vegetation--Comparison with
northern hemisphere--Siberian animals in ice--Embedded in cold
mud--Edible fungus--Zoology--Fucus giganteus--Leave Tierra del
Fuego.
STRAIT OF MAGELLAN.
In the end of May, 1834, we entered for the second time the eastern
mouth of the Strait of Magellan. Having beat our way against wind
and wave we anchored at Gregory Bay, and had an interview with the
so-called gigantic Patagonians; of whom Captain FitzRoy has given so
good an account. The country on both sides of the strait, in this
part, consists of level plains, like those of the rest of Patagonia.
Cape Negro, a little past the second narrow, may be considered as the
point where the land begins to assume the marked features of Tierra
del Fuego. On the east coast, south of the Strait, broken park-like
scenery in a like manner connects these two countries, which are
opposed to each other in almost every point. It is truly surprising
to find in a space of twenty miles such a change in the landscape.
If we take rather a greater distance, as between Port Famine and
Gregory Bay, that is about sixty miles, the difference is still more
wonderful. At the former place we have rounded mountains concealed
by impervious forests, which are drenched with the rain, brought
by an endless succession of gales; while at Cape Gregory there is
a clear and bright blue sky over the dry and sterile plains. The
atmospheric currents,[1] although rapid, turbulent, and unconfined
by any apparent limits, yet seem to follow, like a river in its bed,
a regularly determined course.
JUNE 1ST.--We anchored in the fine bay of Port Famine. It was now
the beginning of winter, and I never saw a more cheerless prospect;
the dusky woods piebald with snow, could be only indistinctly seen
through a drizzling hazy atmosphere. We were, however, lucky in
getting two fine days. On one of these. Mount Sarmiento, a distant
mountain 6800 feet high, presented a very noble spectacle. I was
frequently surprised, in the scenery of Tierra del Fuego, at the
little apparent elevation of mountains really lofty. I suspect it is
owing to a cause, which would not at first be imagined, namely, that
the whole mass, from the summit to the water’s edge, is generally in
full view. I remember having seen a mountain, first from the Beagle
channel, where the whole sweep from the summit to the base was full
in view, and then from Ponsonby Sound across several successive
ridges; and it was curious to observe in the latter case, as each
fresh step afforded means of judging of the distance, how the
mountain appeared to rise in height.
The Fuegians twice came and plagued us. As there were many
instruments, clothes, and men on shore, it was thought necessary to
frighten them away. The first time, a few great guns were fired, when
they were far distant. It was most ludicrous to watch through a glass
the Indians, as often as the shot struck the water, take up stones,
and as a bold defiance, throw them towards the ship, though about a
mile and a half distant! A boat was then sent with orders to fire a
few musket-shot wide of them. The Fuegians hid themselves behind the
trees; and for every discharge of the musket they fired their arrows:
all, however, fell short of the boat, and the officer as he pointed
at them laughed. This made the Fuegians frantic with passion, and
they shook their mantles in vain rage. At last seeing the balls cut
and strike the trees, they ran away; and we were left in peace and
quietness.
On a former occasion, when the Beagle was here in the month of
February, I started one morning at four o’clock to ascend Mount
Tarn, which is 2600 feet high, and is the most elevated point in
this immediate neighbourhood. We went in a boat to the foot of the
mountain (but not to the best part), and then began our ascent. The
forest commences at the line of high-water mark, and during the two
first hours I gave over all hopes of reaching the summit. So thick
was the wood, that it was necessary to have constant recourse to
the compass; for every landmark, though in a mountainous country,
was completely shut out. In the deep ravines, the death-like scene
of desolation exceeded all description; outside it was blowing a
gale, but in these hollows, not even a breath of wind stirred the
leaves of the tallest trees. So gloomy, cold, and wet was every
part, that not even the fungi, mosses, or ferns, could flourish.
In the valleys it was scarcely possible to crawl along, they were
so completely barricaded by the great mouldering trunks, which had
fallen down in every direction. When passing over these natural
bridges, one’s course was often arrested by sinking knee deep into
the rotten wood; at other times, when attempting to lean against
a firm tree, one was startled by finding a mass of decayed matter
ready to fall at the slightest touch. We at last found ourselves
among the stunted trees, and then soon reached the bare ridge, which
conducted us to the summit. Here was a view characteristic of Tierra
del Fuego;--irregular chains of hills, mottled with patches of snow,
deep yellowish-green valleys, and arms of the sea intersecting the
land in many directions. The strong wind was piercingly cold, and the
atmosphere rather hazy, so that we did not stay long on the top of
the mountain. Our descent was not quite so laborious as our ascent;
for the weight of the body forced a passage, and all the slips and
falls were in the right direction.
Captain King has given a sketch of the geology of Tierra del Fuego,
to which I have little to add. A great formation of clay-slate,
rarely containing organic remains, but sometimes presenting casts of
a kind of ammonite, is fronted on the east side by plains belonging
probably to two tertiary epochs. On the west coast, a prolongation of
the grand crevice of the Andes, from which so much heat has escaped
from the interior of the globe, has metamorphosed the slate. There
is, however, a double line, the structure of which I do not quite
comprehend. The interior one consists of granite and mica slate; the
exterior one (perhaps more modern), of greenstone, porphyritic and
other curious trappean rocks. Almost every one at first thinks that
this country owes its grand name of “the Land of Fire,” to the number
of its volcanoes. Such, however, is not the case: I did not see even
a pebble of any volcanic rock, except in Wollaston Island, where some
rounded masses of scoriæ were embedded in a conglomerate of no modern
date. In a geological point of view this circumstance allows us to
consider the grand linear train of ancient and modern volcanoes,
which fall on parallel fissures in the Andes, as extending from
lat. 55° 40′ south to 60° north, a distance little less than seven
thousand geographical miles.
Perhaps the most curious feature in the geology of this country,
is the extent to which the land is intersected by arms of the sea.
These channels, as Captain King remarks, are irregular and dotted
with islands, where the granitic and trappean rocks occur, but in
the clay-slate formation are so straight, that in one instance “a
parallel ruler placed on the map upon the projecting points of the
south shore, extended across, also touched the headlands of the
opposite coast.”
I have heard Captain FitzRoy remark, that on entering any of these
channels from the outer coast, it is always necessary to look out
directly for anchorage; for further inland the depth soon becomes
extremely great. Captain Cook, in entering Christmas Sound, had first
37 fathom, then 40, 60, and, immediately afterwards, no soundings
with 170. This structure of the bottom, I presume, must arise from
the sediment deposited near the mouths of the channels, by the
opposed tides and swell; and likewise from the enormous degradation
of the coast-rocks, caused by an ocean harassed by endless gales.
The Strait of Magellan is extremely deep in most parts, even close to
the shore. About mid-channel eastward of Cape Froward, Captain King
found no bottom with 1536 feet: if, therefore, the water should be
drained off, Tierra del Fuego would present a far more lofty range
of mountains than it does at present. I will not here enter on any
speculations regarding the causes which have produced this remarkable
structure, in a district in which the latter movements at least have
been those of elevation. I may, however, observe, that pebbles, and
great boulders of various and peculiar crystalline rocks, which have
undoubtedly travelled from the south-west coast, lie scattered over
the whole of the eastern part of Tierra del Fuego. One enormous block
of syenite near St. Sebastian Bay was barn-shaped, and had a girth
of 47 feet; it projected five feet above the sand, and appeared to
be deeply buried. The very nearest point to which we can look for
the parent rock, is about ninety miles distant. On the shores of the
Strait of Magellan, near Port Famine, numerous semi-rounded fragments
of various granites and hornblendic rocks are strewed on the beach,
and on the sides of the mountain, to an elevation of thirty or forty
feet. Now to this point the high road from the Southern and Western
shores passes directly over the great abyss of more than 1500 feet
deep. Whatever may have been the means of transport, it has not been
one of indiscriminate violence: for the two places, St. Sebastian
Bay and Shoal Harbour, where the great fragments are most numerous,
certainly existed previously to the last and smallest change of
level, as channels connecting the Strait of Magellan, in the one case
with the open sea, and in the other with Otway Water.
The climate of the southern part of South America presents many
phenomena of the highest interest. It has long been observed that
there exists some essential difference between it, and that of the
countries in the northern hemisphere. I have already remarked on the
surprising contrast between the rank vegetation of the broken west
coast, consequent on the humid climate, as compared with the dry and
sterile plains of Patagonia. The clouded and boisterous state of
the atmosphere is necessarily accompanied by a decrease in extreme
temperature; hence we find that fruits which ripen well, and are very
abundant, such as the grape and fig, in lat. 41° on the east coast,
succeed very poorly in a lower latitude on the opposite side of the
continent.[2] The result is more strongly marked, if we take Europe
as the standard of comparison. In Chiloe, lat. 42°, corresponding
to the northern parts of Spain, peaches require the greatest care,
and seldom produce fruit; but strawberries and apples succeed to
admiration. At Valdivia, lat. 40°, or that of Madrid, standard
peaches bear abundantly; grapes and figs ripen, but are far from
common; olives seldom even partially ripen, and oranges not at all;
yet in Europe this is the parallel most productive of these fruits.
Even at Concepcion, lat. 36°, oranges are not abundant, though the
other named fruits succeed perfectly. At the Falklands, in the
same latitude as the south of England, wheat very seldom comes to
maturity; but we ought to feel little surprise at this, when we hear
that in Chiloe (lat. 42°) the inhabitants are frequently compelled to
cut their corn before it is ready, and bring it into their houses to
dry.
With respect to the climate of Tierra del Fuego during the colder
parts of the year, Captain King has published some most interesting
tables in the Geographical Journal.[3] The Beagle during this voyage,
was employed in the extreme southern parts of the country, from
December 18th to February 20th. From the appearance of the vegetation
during the first part, and from the weather we experienced at the
Falkland Islands, subsequent to the last date, I feel little doubt
that these sixty-five days included the best part of the summer.
Perhaps if another fortnight had been added, the mean would have
been a little higher. The first eighteen of these days were spent
partly at sea, near Cape Horn, and we were drifted for a short time
by bad weather to nearly ninety miles to the southward. The mean
temperature, from observations made every two hours by the officers
on board the Beagle, was 45°. During the succeeding thirty-seven
days[4] the Beagle was at anchor in different harbours a few leagues
north of Cape Horn, and then the mean from observations at 6 A.M.,
noon, and 6 P.M., was 50°. The mean, therefore, between these two
periods, which include the hottest part of the year, is only 47°.5.
The latter of the two periods was unusually warm, but the former much
the contrary, and the station where the observations were made was
a little further to the southward. The whole of these observations
apply to the extreme islands: Captain King’s were made in a central
position 1° 45′ further northward. If from the above considerations
we add two degrees and a half to the mean obtained this voyage, the
result (50°) will probably give the temperature of the hottest part
of the year in central Tierra del Fuego. Captain King gives as the
mean temperature of June 32°.97, of July 33°.03, of the first twelve
days in August 33°.25; answering to our December, January, and
February, which three months appear to be the coldest, and the mean
of these is 33°.08.[5] Dublin is nearly in the same latitude in the
northern hemisphere as Port Famine is in the southern, and we will
take its temperature as a means of comparison.
| Latitudes.| Summer | Winter |Difference.| Mean of
| |Temperature|Temperature| |Summer and
| | | | | Winter.
Dublin[6] | 53° 21′ N.| 59°.54 | 39°.2 | 20°.34 | 49°.37
Port Famine | 53 38′ S.| 50 | 33 .08 | 16 .92 | 41 .54
------------+-----------+-----------+-----------+-----------+----------
Difference | 0 17′ | 9 .54 | 6 .12 | 3 .42 | 7 .83
It will be seen by this that the temperature at Port Famine is very
considerably lower, both during summer and winter, than at Dublin,
and that at the former the difference between the seasons is not
so great, or that the climate is there more equable. It seems the
general opinion of those who have visited this country, that the
frosts are not so severe or so long as in England. The sealers say
that throughout the year they wear the same quantity of clothing.
Nevertheless Captain King states, that during the winter of 1828 the
temperature was once as low as[7] 12°.6. I have drawn up these rough
and approximate statements merely for the sake of illustrating some
of the following remarks.
The kind of climate here described appears to be common to the
_southern_ parts of the whole of the southern hemisphere. Although
so inhospitable to our feelings, and to most of the plants from the
warmer parts of Europe, yet it is most favourable to the native
vegetation. The forests, which cover the entire country between the
latitudes of 38° and 45°, rival in luxuriance those of the glowing
intertropical regions. Whilst in Chiloe (lat. 42°) I could almost
have fancied myself in Brazil. Stately trees of many kinds, with
smooth and highly coloured barks, are loaded by parasitical plants of
the monocotyledonous structure; large and elegant ferns are numerous;
and arborescent grasses intwine the trees into one entangled mass,
to the height of thirty or forty feet above the ground. Palm-trees
grow in lat. 37°; an arborescent grass very like a bamboo in 40°; and
another closely-allied kind, of great length but not erect, even as
far south as 45°.
In another part of this same hemisphere, which has so uniform a
character owing to its large proportional area of sea, Forster
found parasitical orchideous plants living south of lat. 45° in New
Zealand. Tree-ferns thrive luxuriantly near Hobart Town, in Van
Diemen’s Land. I measured one there which was exactly six feet in
circumference; and its height from the ground to the base of the
fronds appeared to be very little under twenty. Mr. Brown says[8]
“an arborescent species of the same genus (_Dicksonia_) was found by
Forster, in New Zealand, at Dusky Bay, in nearly 46° S., the highest
latitude in which tree-ferns have yet been observed. It is remarkable
that, although they have so considerable a range in the southern
hemisphere, no tree-fern has been found beyond the northern tropic:
a distribution in the two hemispheres somewhat similar to this has
been already noticed respecting the Orchideæ that are parasitical on
trees.”
Even in Tierra del Fuego, Captain King describes the “vegetation
thriving most luxuriantly, and large woody stemmed trees of Fuchsia
and Veronica, in England considered and treated as tender plants, in
full flower, within a very short distance of the base of a mountain
covered for two-thirds down with snow, and with the temperature at
36°.” He states, also, that humming-birds were seen sipping the
sweets of the flowers, “after two or three days of constant rain,
snow, and sleet, during which time the thermometer had been at the
freezing point.” I myself have seen parrots feeding on the seeds of
the winter’s bark, south of latitude 55°.
Although the limit of an almost tropical vegetation extends thus
far southward, yet the dearth of living things, both vegetable and
animal, on the islands situated even far without the antarctic
circle, is surprising, compared with the corresponding parallels in
the northern hemisphere. In South Shetland in lat. 62° to 63° (same
as Ferroe, or southern part of Norway) Weddell[9] states, “None of
the islands afford any vegetation save a short straggling grass,
which is found in very small patches in places where there happens to
be a little soil. This, together with a moss similar to that which is
found in Iceland, appears in the middle of January, at which time the
islands are partially clear of snow.” In Deception Island, one of the
same group, Lieutenant Kendall, says,[10] “There was nothing in the
shape of vegetation except a small kind of lichen.” The island itself
is partly composed of ice and volcanic ashes interstratified. Another
curious proof of the rigour of the climate is mentioned: “Having
observed a mound on the hill immediately above this cove, I opened
it, and found a rude coffin, the rotten state of which bespoke its
having been long consigned to the earth; but the body had undergone
scarcely any decomposition. The legs were doubled up, and it was
dressed in the jacket and cap of a sailor, but neither they nor the
countenance were similar to those of an Englishman.”
Sandwich Land, which is nearly three degrees further from the pole,
is thus described, by Captain Cook (February 1st, hottest time in
the year, and in same latitude as north of Scotland): “Every part
was blocked or filled up with ice, and the whole country, from the
summits of the mountains down to the very brink of the cliffs which
terminate the coast, covered many fathoms thick with everlasting
snow. The cliffs alone were all which was to be seen like land.”
Again he adds, talking of two islets, “These only were clear of snow,
and seemed covered with a green turf.” In Georgia, lat. 54° to 55°,
the bays are terminated by ice-cliffs of considerable height, and,
according to Cook, the country “in the very height of summer, is
in a manner wholly covered many fathoms deep with frozen snow, but
more especially on the south-west coast.” The only vegetable is “a
strong-bladed grass growing in tufts, wild burnet, and a plant-like
moss.” Although 96 miles long and about ten broad, it possesses not a
single quadruped, and only one land-bird, namely a small titlark (an
Anthus), a specimen of which I procured in the Falklands. This bird,
if undescribed, certainly well deserves the name of _antarcticus_,
for although not living within that circle, it inhabits a more
inhospitable region than any other terrestrial animal. Anderson, in
Cook’s Voyage, says, even in Kerguelen Land (an island 120 miles long
by 60 broad, and situated in lat. 50°, corresponding to the extreme
southern point of England), “The whole catalogue of plants does not
exceed sixteen or seventeen, including some sorts of moss, and a
beautiful species of lichen which grows upon the rocks higher up than
the rest of the vegetable productions. Nor is there even the least
appearance of a shrub in the whole country.” It is doubtful whether
there is a single land-bird; and then he adds, “The hills are of a
moderate height; yet many of their tops were covered with snow[11] at
this time, though answering to our June.” These statements forcibly
prove the intemperance of the climate even far without the frozen
limits of the antarctic circle.
There are no direct observations, by which to judge of the mean
temperature of the year in these southern islands. But after reading
the above accounts, it will readily be granted that it must be very
low. Even in Georgia, in lat. 54°-55°, it is not improbable that the
soil is perpetually frozen at a few feet beneath the surface. At
Deception Island in lat. 62°-63° from the preservation of the dead
body alluded to, and the interstratification of ice with the volcanic
ashes, we may feel almost sure that such must be the case. In the
northern hemisphere, it is only on the great continents that so low
a mean temperature is found in corresponding latitudes. In North
America, according to Richardson,[12] north of lat. 56°, the thaw
does not penetrate to a greater depth than three feet. In the Steppes
of Siberia, Humboldt[13] states that to the northward of 62°, the
ground between twelve and fifteen feet below the surface is always
frozen. In the space, however, between these two great northern
continents, the line of perpetual congelation rises considerably
towards the north.
It is a remarkable meteorological fact, that in the northern and
southern hemispheres, a low mean temperature, in latitudes without
the frigid zone, is the result of a directly opposite condition
of things. In the northern hemisphere the atmosphere is rendered
extremely cold, from the radiation of a large extent of country
during a long winter; nor is it moderated by the warmer currents of
any neighbouring sea: hence the extreme cold of the winter more than
counterbalances the heat of summer. In the southern hemisphere, on
the other hand, although the winter is moderate, the summer is cold;
for a sky constantly clouded rarely permits the rays of the sun to
warm the surface (itself a bad absorbent) of the great ocean: hence,
the mean temperature of the year falls below the freezing point. It
will at once be evident, that a kind of vegetation which requires an
equable temperature, will approach much nearer the line of perpetual
congelation in a climate such as this of the southern hemisphere,
than in the opposite one subject to extremes.
The height of the plane of perpetual snow in any country, seems
chiefly to be determined by the extreme heat of summer, rather than
by the mean of the year. As the summer in Tierra del Fuego is so very
wretched, we ought not to feel surprised at the fact stated by Capt.
King,--that in the Strait of Magellan, the line descends to about
3500 or 4000 feet. In the northern hemisphere, we must travel about
fourteen degrees nearer the pole to meet with so low a limit, namely,
between lat. 67° and 70° on the mountains of Norway.
In the Cordillera of South America, between latitudes 41° and 43°
30′, the culminant peaks have altitudes pretty nearly equal. Several
were measured by the officers of the Beagle with considerable
care, by angles of elevation, the positions of the mountains being
accurately known. Osorno is 7550 feet; mountain south of Osorno
5609; Minchinmadiva 7046; northern end of same range 6862; Corcovado
7510; Yntales 6725. Not only these points, but a great part of
the range[14] was thickly clothed with snow, in the beginning of
February (answering to our August), which descended some way down
the mountains, and presented to a distant beholder a perfectly
horizontal line. We were assured that the snow, which it appeared
must inevitably be the case, remained throughout the year. On January
26th, after a week of uncommonly fine weather, Mr. King measured
with a pocket sextant, the angle of this line with the summit of
the Corcovado; and subtracting the result from the total height,
the snow-line was found to descend to 4480 feet. It is possible
that there may have existed some unknown cause of error; but as the
average height of the few _highest peaks_ in the _snow-clad range_
is under 7000 feet, it is evident that the height of the snow-line
cannot at most much exceed 6000 feet.
As this is a point of interest, I shall mention a few other
circumstances, by which I think we may come to a nearly definite
conclusion. On February 2d (1835) I obtained the last view of the
Cordillera; on that day the lower line of the snow descended some
way (so as to form a considerable angle with the summit, when viewed
from a distance of 61 miles) on the mountain south of Osorno (lat.
41° 20′), which stands by itself, and has a height of 5607 feet.
Since arriving in England I have received a letter from Mr. Douglas
in Chiloe, who, describing some volcanic phenomena, accidentally
mentions the snow-line. He says, on February 20th (same year), on the
volcano of Minchinmadiva (lat. 42° 48′), which has an elevation of
7046 feet, lava was ejected from a crater “just above the verge of
the snow.” Again, on February 27th, he alludes to the summit of the
Corcovado (7510 feet) being covered with snow, as was Yntales[15]
(6725 feet) in lat. 43° 30′. Again Mr. Douglas, speaking of the
Corcovado, says, “On the 16th of March the snow appeared to cover
one-fifth of its (_visible_) perpendicular height.” By this date
the snow-line must have attained its greatest height (if, indeed,
fresh snow had not fallen); and, as the Corcovado rises in an
unbroken slope close to the sea, the proportion covered by snow might
be judged of, with _some_ degree of accuracy. The height of the
Corcovado (7510 feet) was obtained by three angular measurements,
made by the officers on the survey, and the mean nearly agreed with
the three separate results. Reflecting on all these circumstances, we
may conclude with perfect safety, that the limit of perpetual snow,
between the latitudes 41° and 43°, cannot much, if at all, exceed
6000 feet.
Proceeding northward along the Cordillera we find a very different
condition of things. In the pass of the Portillo (to the southward of
33°) Dr. Gillies determined barometrically the height of the double
range; and he found the two ridges to be respectively 13,210 and
14,365 feet. On March 21st and 22d (1835), shortly before fresh snow
fell, I crossed these mountains,[16] and although there were large
masses of snow, there were much greater spaces at some height on each
side uncovered. Dr. Gillies[17] says, “the summit (of the volcano
of Peuquenes) is generally[18] covered with snow, and its elevation
cannot be less than 15,000 above the level of the sea.” From these
statements, compared with my observations, the snow-line when I
crossed certainly was considerably above 14,365,--we may assume
15,000 as about the limit. From the results obtained by Humboldt,
Pentland, Gillies, and King, we are enabled to draw up the following
table of the extraordinary range of the snow-line on the Cordillera
of South America:
+----------------------+----------------+-------------------------+
| Latitude. | Height in feet | Observer. |
| | of Snow-line. | |
+----------------------+----------------+-------------------------+
| Equatorial region: } | 15,748 | Humboldt. |
| Mean result. } | | |
| | | |
| Bolivia, } | 17,000 | Pentland.[19] |
| Lat. 16°-18° S. } | | |
| | | |
| Central Chile, } | { 14,500 | Gillies. |
| Lat. 33° S. } | { to | |
| | { 15,000 | |
| | | |
| Chiloe, } | 6,000 | Officers of the Beagle. |
| Lat. 41°-43° S. } | | |
| | | |
| Tierra del Fuego, } | { 3,500 | King.[20] |
| 54° S. } | { to | |
| | { 4,000 | |
+----------------------+----------------+-------------------------+
In considering this table, and beginning from the south, we observe,
that through the first twelve degrees, the height of the snow-line
rises only a little more than 2000 feet. In this space the climate
and productions of the country are in many respects very uniform. In
the succeeding nine degrees the rise is no less than nine thousand
feet. Before any one pronounces this to be impossible, let him
reflect well that the height of the snow-line very much depends
on the heat of summer. In Chiloe no fruit, excepting apples and
strawberries, comes to perfection; it is even oftentimes necessary
to carry the barley and corn into the houses to be ripened:[21] on
the other hand, in central Chile, even the sugar-cane[22] has been
cultivated out of doors, and during a long summer of seven months the
sky is seldom clouded, and rain never falls. The island of Chiloe, as
well as the neighbouring mainland, is concealed by one dense forest,
dripping with moisture, and abounding with ferns and other plants
that love a humid atmosphere: while the soil of central Chile, where
not irrigated, is arid and nearly desert. These two countries, so
remarkably opposed to each other in every character, blend together
rather suddenly near Concepcion, in lat. 37°. I do not doubt, the
plain of perpetual snow undergoes an extraordinary flexure in the
district where the forest ceases; for trees indicate a rainy climate,
and hence a clouded state of atmosphere.[23]
From central Chile to Bolivia, a space of 16°, the rise of the
snow-line is only 2000 feet. If Bolivia possessed an atmosphere
as clear as that of Chile, the limit in all probability would be
even higher than the present 17,000. The cause why the limit in the
equatorial regions should be lower than in a latitude seventeen
degrees to the southward, I leave to those to explain, who have more
means of information respecting the dryness and clouded state of the
atmosphere in the respective regions.
The presence of glaciers depends on the accumulation of a large
mass of snow, subject to some variations of temperature, sufficient
partially to thaw, and then reconsolidate the mass in its downward
course. They have been aptly compared to gigantic icicles. The lower
limit of glaciers, must depend on that of the parent snow, greatly
affected by the form of the land: in Tierra del Fuego the snow-line
descends very low, and the mountain sides are abrupt; therefore we
might expect to find glaciers extending far down their flanks.[24]
Nevertheless, when on first beholding, in the middle of summer, many
of the creeks on the northern side of the Beagle channel terminated
by bold precipices of ice overhanging the salt water, I felt greatly
astonished. For the mountains from which they descended, were far
from being very lofty. Captain FitzRoy from angular measurements
considers the general range to have an elevation rather under 4000
feet, with one point called Chain Mountain rising to 4300. Further
inland, there is indeed a more lofty mountain of 7000 feet, but it
is not directly connected with the glaciers to which I now allude.
This range, which exceeds by so little the height of some mountains
in Britain, which yet sends down in the middle of summer its frozen
streams to the sea-coast, is situated in the latitude of the
Cumberland hills.
I was much interested by observing the great difference between the
matter brought down by torrents and by glaciers. In the former case
a spit of gravel is formed, but in the latter a pile of boulders. On
one occasion, the boats being hauled on shore, within the distance of
half a mile from a glacier, we were admiring the perpendicular cliff
of blue ice, and wishing that some more fragments would fall off,
like those we saw floating on the water, at a distance of more than
a mile from their source. At last, down came a mass with a roaring
noise, and immediately we saw the smooth outline of a wave travelling
towards us. The men ran down as quickly as they could to the boats;
for the chance of their being dashed to pieces was evident. One of
the seamen just caught hold of the bows, as the curling breaker
reached it: he was knocked over and over but not hurt; and the boats,
though thrice lifted on high and let fall again, received no damage.
This was most fortunate for us, for we were a hundred miles distant
from the ship, and we should have been left without provisions or
fire-arms.
I had previously observed that some large fragments of rock on the
beach had been lately displaced: but until seeing this wave I did
not understand the cause. The structure of the creek in which this
happened was very curious. One side was formed by a spur of mica
slate (of which rock the surrounding mountains were composed); the
head by a cliff of ice about forty feet high; and the other side
by a promontory which was built up of huge rounded fragments of
granite and mica slate, and was more than fifty feet in height. To
account for the present position of these blocks, where they must
have long remained, for old trees were growing on the upper parts; we
must suppose, either that the glacier formerly advanced half a mile
further outward, or that the land stood at a rather different level.
Whether we are able fully to account, or not, for the height and size
of this promontory of boulders, certainly it must have been the work
of the glacier. One semi-rounded fragment of granite lying just above
high-water mark, was of enormous dimensions. It projected six feet
above the sand, and was buried to an unknown depth: its shape was
oval with a circumference of thirty yards, so that the longer axis
probably measured about ten or eleven. This fragment must have come
from the higher parts of the range; for the base of the mountain was
entirely composed of mica slate.
The waves caused by the fall of the ice must be a most powerful
agent in rounding and heaping together these huge fragments, and
likewise in wearing away projecting points of the solid rock. In
Georgia, situated in the very same latitude, Cook, speaking of the
great ice-cliffs at the head of every harbour, says, “pieces were
continually breaking off, and floating out to sea, and a great
fall happened while we were in the bay, which made a noise like
cannon.” He adds, “It can hardly be doubted, that a great deal of
ice is formed here in winter, which in the spring is broken off,
and dispersed over the sea.” Mr. Sorrell, the boatswain of the
Beagle, who has long been accustomed to these seas, informs me, that
at this season he has seen small icebergs, with mud and gravel on
them, floating from the shores. I have heard from another quarter
of the same circumstance. Captain Hunter[25] says, he met numerous
ice-islands in this neighbourhood, and that “many were half black
apparently with earth from the land, to which they had adhered, or
else with mud from the bottom on which they had been formed.” By
the latter method large fragments might easily be transported, and
unless the iceberg should be upset, they would never be discovered.
Nevertheless, the islands of ice floating in the southern ocean, and
especially those occurring far south, appear generally to be quite
free from all impurities excepting the dung of seafowl. Captain
Biscoe, who extended his enterprising researches so far towards the
antarctic pole, informs me in a letter that he never observed in a
single instance[26] any mud or fragments of stone on the numerous
icebergs which he encountered during his voyage.
Glaciers occur at the head of the sounds along the whole western
coast of the southern part of South America. Looking at the chart
I find sixteen places mentioned: besides these I know of several
others, such as those in the Beagle channel and at the foot of Mount
Sarmiento. The sounds, moreover, were not all traced to the head,
and it is in this part that the glaciers most frequently occur. Of
the sixteen referred to, many include several frozen arms coming
down from one vast body of ice. In the Canal of the Mountains, for
instance, no less than nine descend from a mountain, the whole side
of which, according to the chart, is covered by a glacier of the
extraordinary length of twenty-one miles, and with an average breadth
of a mile and a half. It must not be supposed that the glacier
merely ascends some valley for the twenty-one miles, but it extends
apparently at the same height for that length, parallel to the sound;
and here and there sends down an arm to the sea-coast.[27] There are
other glaciers having a similar structure and position, with a length
of ten and fifteen miles.
I will now specify a few of the more remarkable cases, taken from
Captain King’s paper, to which I have so often referred. The canal of
St. Andrew is said by Lieutenant Skyring to be “suddenly and boldly
closed by tremendous and astonishing glaciers.” The highest mountain
in this part (Mount Stokes) was ascertained during our ascent of
the river of St. Cruz to be 6200 feet, and this certainly exceeds
considerably the height of the general range. About ninety miles to
the northward, Sir G. Eyre’s Sound, in the latitude of Paris, has its
several arms terminated by glaciers. Mr. Bynoe, the surgeon of the
Beagle, who accompanied the boat when this part was surveyed, informs
me that about mid-channel, and more than _twenty_ miles from the head
of the sound, there were great numbers of floating masses of ice.
Standing in the boat he supposes he saw about fifty: he, together
with four of the boat’s crew, landed on one, which although only two
or three feet above the surface of the water, felt quite steady, and
easily supported their weight. On the surface, in the central part,
a mass of granite, of an angular form, was partly embedded; and the
ice had thawed all round it, so as to form a shallow pool of water.
It was a cube of nearly two feet; and Mr. Bynoe with a maul knocked
off, and brought away, a piece as large as a man’s head. The iceberg
was still floating, and drifting outwards: even if it had been
stranded in the immediate neighbourhood, the block of granite would
have rested on the clay-slate of the surrounding mountains. For the
parent rock we must look to the higher parts of the range, near the
head of the sound.
Again, a few miles to the northward I see in the chart an _Iceberg_
Sound, which no doubt was so called from the number of floating
masses of ice. It may be recollected that in this latitude, on
the opposite side of the Cordillera, the plains of St. Cruz, at
the distance of fifty and sixty miles from the mountains, were
strewed with great fragments of rock. Of these, one was sixty feet
in circumference, and another, which was angular, measured five
yards square;--both being partly buried in the gravel, so that
their thickness was unknown. As it is probable that the plains were
covered by the sea within a period geologically recent, and as we
absolutely know, that icebergs at the present day, both in the same
latitude and even further northward, are transporting angular blocks
from the opposite side of the Cordillera, the explanation of the
St. Cruz case through the same means of transport, is rendered so
evidently probable, that we are not justified in doubting to receive
it: more especially as the unbroken surface of those plains, and
the terrace-formed valley, opposes a very great difficulty to the
admission of any violent debacle. The latitudes which we have now
been talking of, correspond to the southern extremity of Cornwall,
and the northern provinces of France.
I will add only one other case; namely, the occurrence of glaciers
at the level of the sea, in the gulf of Penas, latitude 46° 40′.
A glacier is represented in the charts as in one part abutting on
_a flat swamp often inundated_, and in another reaching to the
head of Kelly Harbour. The accompanying woodcut is copied from the
published charts. Captain King says its length is fifteen miles,
and from the chart one part is seven broad; it is also described as
being lofty; so that we here have an enormous mountain, covering
a wide area, composed of ice. If we compare its situation with
countries in the northern hemisphere, the corresponding parallel
crosses the Alps of Switzerland. Or we may state the case stronger,
by saying that glaciers here descend to the sea within less than
nine degrees of latitude, from where palms grow, less than two and a
half from arborescent grasses, and (looking to the westward in the
same hemisphere) less than two from orchideous parasites, and within
a single degree of tree-ferns! In Norway, Von Buch found glaciers
descending to the sea at Kunnen in latitude 67°; that is twenty
degrees nearer the pole, than in this hemisphere;--a difference of
latitude rather greater than that between the snow-lines of equal
altitude in the same two countries.
[Illustration: (Chart of Kelly Harbor.)]
The survey of the _inner_ coast terminated at the gulf of Penas,
so that I am far from knowing whether glaciers are not found much
further northward: and considering the immense size of the one just
described, it is extremely improbable that it should be the last. On
the island of Chiloe, which fronts the Cordillera as the Jura does
the Alps, many angular fragments of granite, of an enormous size,
which appear to have crossed the inland arm of sea, lie scattered
at different heights over the country. Although situated between
the parallels of 41° and 43°, I know of no sound objection to the
supposition that these might formerly have been floated across,
on icebergs produced by the fall of glaciers. We are not bound to
suppose that the latitude 46° 40′ has always been the northern limit
of such phenomena, even if it _should_ be so at present. We have
endeavoured to show that the snow-line in the parallel of Chiloe has
an elevation of about 6000 feet; and since on Mont Blanc the glaciers
descend 5160 feet beneath the line of perpetual snow, we might at
present expect to find them in front of Chiloe at a very small
altitude above the level of the sea.
With respect to the position of the glaciers, they seem to occur
only within the deep sounds which penetrate the central Cordillera.
This may be attributed chiefly to the subordinate elevation of the
outer lines. When we consider the vast dimensions and number of these
glaciers, the effect produced on the land must be very great. Every
one has heard of the mass of rubbish propelled by the glaciers of
Switzerland, as they slowly creep onwards. In the same manner in
Tierra del Fuego, on a still night the cracking and groaning of the
great moving mass may be distinctly heard. The same force, which is
known to uproot whole forests of lofty trees, must, when grating
over the surface, tear from the flanks of the mountain many huge
fragments of rock. Beneath each glacier, also, a roaring torrent
drains the upper part of the ice. To these effects, which are common
to all cases, there must be added, in this country, the wear and tear
of the waves produced by each successive fall. Nor can this agency
be inconsiderable, when we remember that it goes on night and day,
century after century. We must look at every portion of the mountain
as having, during the gradual rising of the land, been successively
exposed to the action of these combined forces.
It is, perhaps, useless to speculate on the effects of earthquakes
without some positive data. But as we find in the immediate
neighbourhood of that great glacier, which stands in the latitude
of the Alps, Byron[28] mentioning with surprise the quantities of
sea-shells lying on all the hill-tops (a fact which may be taken as
a proof of recent continental elevations); and Bulkeley,[29] in his
narrative, saying, “This day we felt four great earthquakes, three
of which were very terrible;” we may feel well assured, that the
same power, which in Chile causes such vast masses of rock and soil
to fall from the sea-cliffs, has oftentimes precipitated fragments
far more immense, of a mass traversed by great fissures, already in
motion, and resting on an inclined plane. I cannot imagine any scene
of more terrific violence, than the waves produced by such a fall: we
know that they are very bad from the mere oscillation, consequent on
the movements of the ground; but in this case I can readily believe
that the water would be fairly beaten back out of the deepest inlet,
and then returning with an overwhelming force, would whirl about
rocks of vast size like so much chaff.
In after ages, with a climate modified by the process of such
physical changes as are now going on throughout the greater part of
this continent, the effects which had been produced by these glaciers
would appear inexplicable, to a person who doubted the possibility of
their occurrence in such latitudes. He would see in the most retired
and protected valleys (the present channels) beaches composed of
great rounded boulders, such as those heaped up on the shore of the
most turbulent ocean. Then perhaps he would speculate, either that
the outer chain of mountains had been elevated subsequently to the
interior ones, so as to protect a coast hitherto exposed, or that
overwhelming deluges had swept down the valleys, and in some manner
produced, in one day, the effects of attrition which on ordinary
occasions require the prolonged action of centuries.
If we could at the present day submerge the greater part of Tierra
del Fuego, or leave unelevated that which we know has recently been
gained, an island with a few small outliers would be formed, similar
to Georgia, and situated in exactly the same latitude. Have we in
such case the slightest right to deny the probability that the
snow-line would descend nearly to the water’s edge, and that every
valley would be “terminated by a wall of ice,” and that “in winter
masses would be broken off and dispersed over the sea?”--all of which
circumstances are now happening in Georgia. The currents, which
always set from the westward towards the east, would drift these
floating masses through the channels towards the eastern side. And
as we know that icebergs at the present day, in both hemispheres,
occasionally transport fragments of rock, so we cannot deny that
those of Tierra del Fuego might formerly have done so. When the land
was elevated, the fragments of rock would be found deposited on the
eastern side of the continent, in bands representing the ancient
channels. Whether or not the hypothesis of their transport be true,
such is the position of the erratic blocks in Tierra del Fuego.
With respect to the general theory of the transport by great
fragments of ice, especially of such as are angular, I may add a few
remarks. Humboldt having observed that none occurred over the vast
intertropical plains of the eastern side of South America, believed
that they were entirely absent from the whole continent. As far as
I am able to discover from the works of travellers, and from what
I have myself seen, the remark holds good in the countries on both
sides of the Cordillera as far south as central Chile. Azara has
particularly stated such to be the case in Chaco. With respect to the
tributaries of the Amazons, nothing can more strongly prove it than
La Condamine’s[30] story. He says, “Below Borja even for four or five
hundred leagues, a stone, even a single flint, is as great a rarity
as a diamond would be. The savages of those countries don’t know what
a stone is, and have not even a notion of it. It is diversion enough
to see some of them when they come to Borja, and first meet with
stones, express their admiration at them with signs, and be eager
to pick them up, loading themselves therewith as with a valuable
merchandise.” It is therefore a remarkable circumstance that as soon
as we reach the colder latitudes in the southern hemisphere (from 41°
to Cape Horn), the same phenomenon occurs, almost on as grand a scale
and with similar limits, as in the northern parts both of the Old and
New World. Neither in the southern nor in the northern hemisphere do
the fragments, coming from the polar regions, or from other mountain
groups, arrive within a considerable distance of the lines of the
tropics.
We must couple the absence of erratic blocks along that part of the
Andes which is situated under a warmer climate, with the similar
non-occurrence, as I am informed by Professor Royle, in Northern
India round the flanks of the Himmalaya;--those loftiest pinnacles
on the face of the globe. With regard to Southern Africa, from lat.
35° to the tropic, Dr. Andrew Smith, who has visited as a naturalist
so large a portion of the interior, assures me he has never seen
any thing of the kind. Nor do I recollect meeting with any mention
of them, in the works of the numerous travellers in the equatorial
regions of the same continent. The same remark certainly holds
good with Australia in the parallel of Sydney, but perhaps is more
doubtful with respect to Van Diemen’s Land.[31] To my mind these
negative facts[32] have very great weight in support of the mass of
positive evidence which Mr. Lyell[33] has brought to bear upon the
question.
The circumstance of a luxuriant vegetation with a tropical character
so largely encroaching on the temperate zones, under the same kind of
climate that allows of a limit of perpetual snow of little altitude,
and consequent descent of the glaciers into the sea, is very
important; because it has been argued, with great apparent truth,
that as there is the strongest presumptive evidence of a gradual
cooling down of the climate (or rather of a less favourable state
for tropical productions) in Europe, it is most unphilosophical to
imagine that formerly glaciers could have acted where they do not now
occur. It may be asked; what are the circumstances in the southern
hemisphere that produce such results? Must we not attribute them to
the large proportional area of water; and do not plain geological
inferences compel us to allow, that during the epoch anterior to the
present, the northern hemisphere more closely approached to that
condition, than it now does?
We are all so much better acquainted with the position of places
in our own, than in any other quarter of the globe, that I will
recapitulate what is actually taking place in the southern
hemisphere,[34] only transporting in imagination each part to a
corresponding latitude in the north. On this supposition, in the
southern provinces of France, magnificent forests, intwined by
arborescent grasses, and the trees loaded with parasitical plants,
would cover the face of the country. In the latitude of Mont Blanc,
but on an island as far eastward as central Siberia, tree-ferns and
parasitical orchideæ would thrive amidst the thick woods. Even as
far north as central Denmark, humming-birds might be seen fluttering
about delicate flowers, and parrots feeding amidst the evergreen
woods, with which the mountains would be clothed down to the water’s
edge. Nevertheless, the southern part of Scotland (only removed
twice as far to the westward) would present an island “almost wholly
covered with everlasting snow,” and having each bay terminated by
ice-cliffs, from which great masses yearly detached, would sometimes
bear with them fragments of rock. This island would only boast of one
land-bird, a little grass and moss; yet in the same latitude the sea
might swarm with living creatures. A chain of mountains, which we
will call the Cordillera, running north and south through the Alps
(but having an altitude much inferior to the latter), would connect
them with the central part of Denmark. Along this whole line nearly
every deep sound would end in “bold and astonishing glaciers.” In
the Alps themselves (with their altitude reduced by about half) we
should find proofs of recent elevations, and occasionally terrible
earthquakes would cause such masses of ice to be precipitated into
the sea, that waves tearing all before them, would heap together
enormous fragments, and pile them up in the corners of the valleys.
At other times, icebergs, “charged with no inconsiderable blocks of
granite,”[35] would be floated from the flanks of Mont Blanc, and
then stranded on the outlying islands of the Jura. Who then will deny
the possibility of these things having actually taken place in Europe
during a former period, and under circumstances known to be different
from the present, when on merely looking to the other hemisphere, we
see they are among the daily order of events?
To the northward of our new Cape Horn, we should only have certain
knowledge of a few island groups, situated in the latitude of the
south part of Norway, and others in that of Ferroe. These, in the
middle of summer, would be buried under snow, and surrounded by
walls of ice; so that scarcely a living thing of any kind would be
supported on the land. If some bold navigator attempted to penetrate
beyond these islands towards the pole, he would run a thousand
dangers, and only meet an ocean strewed with mountain-masses of ice.
At the Ferroe islands (or we may say a little to the southward of the
Wiljui, where Pallas found (in lat. 64° N.) the frozen rhinoceros),
a body buried under the surface of the soil would undergo so little
decomposition, that years afterwards (as in the instance mentioned
at South Shetland, 62°-63° S.), every feature might be recognised
perfect and unchanged. I particularly allude to this circumstance,
because the case of the Siberian animals preserved with their flesh
in the ice, offers the same apparent difficulty with the glaciers;
namely, the union in the same hemisphere of a climate in some senses
severe, with one allowing of the life of those forms which _at
present_, although abounding _without_ the tropics, do not approach
the frozen zones.
The perfect preservation of the Siberian animals, perhaps presented,
till within a few years, one of the most difficult problems which
geology ever attempted to solve. On the one hand it was granted,
that the carcasses had not been drifted from any great distance
by any tumultuous deluge, and on the other it was assumed as
certain, that when the animals lived, the climate must have been so
totally different, that the presence of ice in the vicinity was as
incredible, as would be the freezing of the Ganges. Mr. Lyell in his
“Principles of Geology”[36] has thrown the greatest light on this
subject, by indicating the northerly course of the existing rivers
with the probability that they formerly carried carcasses in the same
direction; by showing (from Humboldt) how far the inhabitants of
the hottest countries sometimes wander; by insisting on the caution
necessary in judging of habits between animals of the same genius,
when the species are not identical; and especially by bringing
forward in the clearest manner the probable change from an insular to
an extreme climate, as the consequence of the elevation of the land,
of which proofs have lately been brought to light.[37]
In a former part of this volume, I have endeavoured to prove, that
as far as regards the _quantity_ of food, there is no difficulty in
supposing that these large quadrupeds inhabited sterile regions,
producing but a scanty vegetation. With respect to temperature, the
woolly covering both of the elephant and the rhinoceros seems at
once to render it at least probable (although it has been argued
that some animals living in the hottest regions are thickly clothed)
that they were fitted for a cold climate. I suppose no reason can be
assigned why, during a former epoch, when the pachydermata abounded
over the greater part of the world, some species should not have
been fitted for the northern regions, precisely as now happens with
deer and several other animals.[38] If, then, we believe that the
climate of Siberia, anteriorly to the physical changes above alluded
to, had some resemblance with that of the southern hemisphere at
the present day--a circumstance which harmonizes well with other
facts,[39] as I think has been shown by the imaginary case, when we
transported existing phenomena from one to the other hemisphere,--the
following conclusions may be deduced as probable: First, that the
degree of cold formerly was not excessive; secondly, that snow did
not for a long time together cover the ground (such not being the
case at the extreme parts 55°-56° of S. America); thirdly, that the
vegetation partook of a more tropical character than it now does in
the same latitudes; and lastly, that at but a short distance to the
northward of the country thus circumstanced (even not so far as where
Pallas found the entire rhinoceros), the soil might be perpetually
congealed: so that if the carcass of any animal should once be buried
a few feet beneath the surface, it would be preserved for centuries.
Both Humboldt[40] and Lyell have remarked, that at the present day,
the bodies of any animals, wandering beyond the line of perpetual
congelation which extends as far south as 62°, if once embedded by
any accident a few feet beneath the surface, would be preserved for
an indefinite length of time: the same would happen with carcasses
drifted by the rivers; and by such means the extinct mammalia may
have been entombed. There is only one small step wanting, as it
appears to me, and the whole problem would be solved with a degree
of simplicity very striking, compared with the several theories
first invented. From the account given by Mr. Lyell of the Siberian
plains, with their innumerable fossil bones, the relics of many
successive generations, there can be little doubt that the beds
were accumulated either in a shallow sea, or in an estuary. From
the description given in Beechey’s voyage of Eschscholtz Bay, the
same remark is applicable to the north-west coast of America:
the formation there appears identical with the common littoral
deposits[41] recently elevated, which I have seen on the shores
of the southern part of the same continent. It seems also well
established, that the Siberian remains are only exposed where the
rivers intersect the plain. With this fact, and the proofs of recent
elevation, the whole case appears to be precisely similar to that of
the Pampas: namely, that the carcasses were formerly floated into
the sea, and the remains covered up in the deposits which were then
accumulating. These beds have since been elevated; and as the rivers
excavate their channels the entombed skeletons are exposed.
Here then, is the difficulty: how were the carcasses preserved at
the bottom of the sea? I do not think it has been sufficiently
noticed; that the preservation of the animal with its flesh was an
occasional event, and not directly consequent on its position far
northward. Cuvier[42] refers to the voyage of Billing as showing that
the _bones_ of the elephant, buffalo, and rhinoceros, are nowhere
so abundant as on the islands between the mouths of the Lena and
Indigirska. It is even said that excepting some hills of rock, the
whole is composed of sand, ice, and bones. These islands lie to
the northward of the place where Adams found the mammoth with its
flesh preserved, and even ten degrees north of the Wiljui, where the
rhinoceros was discovered in a like condition. In the case of the
_bones_ we may suppose that the carcasses were drifted into a deeper
sea, and there remaining at the bottom, the flesh decomposed.[43]
But in the second and more extraordinary case, where putrefaction
seems to have been arrested, the body probably was soon covered up by
deposits which were then accumulating. It may be asked, whether the
mud a few feet deep, at the bottom of a shallow sea which is annually
frozen, has a temperature higher than 32°? It must be remembered
how intense a degree of cold is required to freeze salt water; and
that the mud at some depth below the surface, would have a low mean
temperature, precisely in the same manner as the subsoil on the land
is frozen in countries which enjoy a short but hot summer. If this be
possible,[44] the entombment of these extinct quadrupeds is rendered
very simple; and with regard to the conditions of their former
existence, the principal difficulties have, I think, already been
removed.
* * * * *
Having concluded this long discussion on the analogies which may be
drawn from the existing climate of the southern parts of America,
together with its productions, we will return to the description of
Tierra del Fuego.
There is one vegetable production in this country which is worthy of
mention, as it affords a staple article of food to the aborigines.
It is a globular fungus of a bright yellow colour, and of about the
size of a small apple, which adheres in vast numbers to the bark of
the beech-trees. It probably forms a new genus, allied to the morell.
In the young state it is elastic and turgid, from being charged with
moisture. The external skin is smooth, yet slightly marked with
small circular pits, like those from the smallpox. When cut in two,
the inside is seen to consist of a white fleshy substance, which
viewed under a high power resembles, from the numerous thread-like
cylinders, vermicelli. Close beneath the surface, cup-shaped balls,
about one-twelfth of an inch in diameter, are arranged at regular
intervals. These cups are filled with a slightly adhesive, yet
elastic, colourless, quite transparent matter; and from the latter
character they at first appeared empty. These little gelatinous balls
could be easily detached from the surrounding mass, except at the
upper extremity, where the edge divided itself into threads, which
mingled with the rest of the vermicelli-like mass. The external skin
directly above each of the balls is pitted, and as the fungus grows
old, it is ruptured, and the gelatinous mass, which no doubt contains
the sporules, is disseminated. After this process of fructification
has taken place, the whole surface becomes honeycombed, with empty
cells (as represented in the accompanying woodcut), and the fungus
shrinks, and grows tougher. In this state it is eaten by the
Fuegians, in large quantities, uncooked, and when well chewed has a
mucilaginous and slightly sweet taste, together with a faint odour
like that of a mushroom. Excepting a few berries of a dwarf arbutus,
which need hardly be taken into the account, these poor savages never
eat any other vegetable food besides this fungus.[45]
[Illustration: (Drawing of the edible fungus.)]
I have already mentioned the sombre and dull character of the
forests,[46] in which two or three species of trees grow, to the
exclusion of all others. Above the forest land, there are many
dwarf alpine plants, which all spring from the mass of peat, and
help to compose it. The central part of Tierra del Fuego, where the
clay-slate formation occurs, is most favourable to the growth of
trees; on the outer coast the poorer granitic soil, and a situation
more exposed to the violent winds, do not allow of their attaining
any great size. Near Port Famine I have seen more large trees than
any where else: I measured a winter’s bark which was four feet
six inches in girth, and several of the beech were thirteen feet.
Captain King also mentions one of the latter which was seven feet in
diameter, seventeen feet above the roots.
The zoology of Tierra del Fuego, as might have been expected from
the nature of its climate and vegetation, is very poor. Of mammalia,
besides Cetacea and Phocæ, there is one bat, a mouse with grooved
front teeth (_Reithrodon_ of Waterhouse), and two other species, the
tucutuco (the greater number of these rodents are confined to the
eastern and dry part), a fox, sea-otter, guanaco, and one deer. The
latter animal is rare, and is not, I believe, to be found south of
the Strait of Magellan, as happens with the others.
Observing the general correspondence of the cliffs of soft sandstone,
mud, and shingle, on the opposite sides of the Strait, together
with those on some intervening islands, one is strongly tempted to
believe that the land was once joined, and thus allowed animals so
delicate and helpless as the tucutuco, and Reithrodon, to pass over.
The correspondence of the cliffs is far from proving any junction;
because such cliffs generally are formed by the intersection of
sloping deposits, which, before the elevation of the land, had
been accumulated near the then existing shores. It is, however, a
remarkable coincidence, that in the two large islands cut off by the
Beagle channel from the rest of Tierra del Fuego, one has cliffs
composed of matter that may be called stratified alluvium, which
front similar ones on the opposite side of the channel,--while the
other is exclusively bordered by the older rocks: in the former,
called Navarin Island, both foxes and guanacoes occur; but in
the latter, Hoste Island, although similar in every respect, and
only separated by a channel a little more than half a mile wide,
I have the word of Jemmy Button for saying that neither of these
animals are found. I must confess to an exception to the rule, in
the presence of a small mouse, of a species occurring likewise in
Patagonia.
The gloomy woods are inhabited by few birds: occasionally the
plaintive note of a white-tufted tyrant-flycatcher may be heard,
concealed near the summit of the most lofty trees; and more rarely
the loud strange cry of a black woodpecker, with a fine scarlet crest
on its head. A little, dusky-coloured wren (_Scytalopus fuscus_)
hops in a skulking manner among the entangled mass of the fallen
and decaying trunks. But the creeper (_Synallaxis Tupinieri_) is
the commonest bird in the country. Throughout the beech forests,
high up and low down, in the most gloomy, wet, and impenetrable
ravines, it may be met with. This little bird no doubt appears more
numerous than it really is, from its habit of following, with seeming
curiosity, any person who enters these silent woods: continually
uttering a harsh twitter, it flutters from tree to tree, within a
few feet of the intruder’s face. It is far from wishing for the
modest concealment of the true creeper (_Certhia familiaris_), nor
does it, like that bird, run up and down the trunks of trees; but
industriously, after the manner of a willow wren, hops about, and
searches for insects on every twig and branch. In the more open
parts three or four species of finches, a thrush, a starling (or
_Icterus_), two furnarii, and several hawks and owls occur.
The absence of any species whatever in the whole class of Reptiles is
a marked feature in the zoology of this country, as well as in that
of the Falkland Islands. I do not ground this statement merely on my
own observation, but I heard it from the Spanish inhabitants of the
latter place, and from Jemmy Button with regard to Tierra del Fuego.
On the banks of the St. Cruz in 50° south, I saw a frog; and it is
not improbable that these animals, as well as lizards, may be found
as far south as the Strait of Magellan, where the country retains the
character of Patagonia; but within the damp and cold limit not one
occurs. That the climate would not have suited some of the orders,
such as lizards, might have been foreseen; but with respect to frogs,
this was not so obvious.
Coleopterous insects occur in very small numbers. Until I had
endeavoured by every means to find them, I could not believe, that
a country as large as Scotland, covered with vegetable productions,
and with a variety of stations, would ever have been so unproductive.
The greater part of my small collection consists of alpine insects
(_Harpalidæ_ and _Heteromera_) found beneath stones, above the limit
of the forest. Lower down, with the exception of some few Curculiones
scarcely any could be found. The Chrysomelidæ, which are so
pre-eminently characteristic of the Tropics, are here almost entirely
absent.[47] This must depend on the climate; for the quantity of
vegetable matter is superfluously great. In the hottest part of the
summer the mean of the maxima for thirty-seven successive days was
55°, and the thermometer on some of the days rose to 60°; yet there
were no orthoptera, very few diptera, lepidoptera, or hymenoptera.
In the pools of water I found but few aquatic beetles, and not any
fresh-water shells. Succinea at first appears an exception; but here
it must be called a terrestrial species, for it lives on the damp
herbage far from water. Land-shells could only be procured in the
same situations with the alpine beetles. I have already contrasted
the climate, as well as the general appearance of Tierra del Fuego
with that of Patagonia; and the difference is strongly exemplified
in the entomology. I do not believe they have a species in common;
certainly the general character of the insects is widely different.
If we turn from the land to the sea, we shall find the latter as
abundantly stocked with living creatures as the former is poorly
so. In all parts of the world a rocky and partially protected shore
perhaps supports, in a given space, a greater number of individual
animals than any other kind of station. Here, under every stone,
numerous crawling creatures swarmed, and especially crustacea of
the family of _Cymothoades_. The number of Sphæroma was truly
wonderful: as these animals, when coiled up, have some resemblance
to Trilobites, they were an interesting sight to a geologist. On the
tidal rocks patelliform shells of large size were very abundant.
Even at the depth of forty or fifty fathoms, the bottom of the sea
was far from sterile, as was shown by the abundance of small strong
corallines.
There is one marine production, which from its importance is worthy
of a particular history. It is the kelp or _Fucus giganteus_ of
Solander. This plant grows on every rock from low-water mark to a
great depth, both on the outer coast and within the channels. I
believe, during the voyages of the Adventure and Beagle, not one
rock near the surface was discovered, which was not buoyed by this
floating weed. The good service it thus affords to vessels navigating
near this stormy land is evident; and it certainly has saved many a
one from being wrecked. I know few things more surprising than to see
this plant growing and flourishing amidst those great breakers of the
western ocean, which no mass of rock, let it be ever so hard, can
long resist. The stem is round, slimy, and smooth, and seldom has a
diameter of so much as an inch. A few taken together are sufficiently
strong to support the weight of the large loose stones to which in
the inland channels they grow attached; and some of these stones are
so heavy, that when drawn to the surface they can scarcely be lifted
into a boat by one person.
Captain Cook, in his second voyage, says, that at Kerguelen Land
“some of this weed is of a most enormous length, though the stem is
not much thicker than a man’s thumb. I have mentioned, that on some
of the shoals upon which it grows, we did not strike ground with a
line of twenty-four fathoms. The depth of water, therefore, must
have been greater. And as this weed does not grow in a perpendicular
direction, but makes a very acute angle with the bottom, and much of
it afterwards spreads many fathoms on the surface of the sea, I am
well warranted to say that some of it grows to the length of sixty
fathoms and upwards.” Certainly at the Falkland Islands, and about
Tierra del Fuego, extensive beds frequently spring up from ten and
fifteen fathom water. I do not suppose the stem of any other plant
attains so great a length as 360 feet, as stated by Captain Cook. Its
geographical range is very considerable; it is found from the extreme
southern islets near Cape Horn, as far north, on the eastern coast
(according to information given me by Mr. Stokes), as lat. 43°,--and
on the western it was tolerably abundant, but far from luxuriant,
at Chiloe, in lat. 42°. It may possibly extend a little further
northward, but is soon succeeded by a different species. We thus have
a range of fifteen degrees in latitude; and as Cook, who must have
been well acquainted with the species, found it at Kerguelen Land, no
less than 140° in longitude.
The number of living creatures of all orders, whose existence
intimately depends on the kelp, is wonderful. A great volume might
be written, describing the inhabitants of one of these beds of
sea-weed. Almost every leaf, excepting those that float on the
surface, is so thickly incrusted with corallines, as to be of a white
colour. We find exquisitely-delicate structures, some inhabited
by simple hydra-like polypi, others by more organized kinds, and
beautiful compound Ascidiæ.[48] On the flat surfaces of the leaves
various patelliform shells, Trochi, uncovered molluscs, and some
bivalves are attached. Innumerable crustacea frequent every part of
the plant. On shaking the great entangled roots, a pile of small
fish, shells, cuttle-fish, crabs of all orders, sea-eggs, starfish,
beautiful Holuthuriæ (some taking the external form of the nudibranch
molluscs), Planariæ, and crawling nereidous animals of a multitude
of forms, all fall out together. Often as I recurred to a branch
of the kelp, I never failed to discover animals of new and curious
structures. In Chiloe, where, as I have said, the kelp did not thrive
very well, the numerous shells, corallines, and Crustacea were
absent; but there yet remained a few of the flustraceæ, and some
compound Ascidiæ; the latter, however, were of different species from
those in Tierra del Fuego. We here see the fucus possessing a wider
range than the animals which use it as an abode.
I can only compare these great aquatic forests of the southern
hemisphere with the terrestrial ones in the intertropical regions.
Yet if the latter should be destroyed in any country, I do not
believe nearly so many species of animals would perish, as, under
similar circumstances, would happen with the kelp. Amidst the leaves
of this plant numerous species of fish live, which nowhere else would
find food or shelter; with their destruction the many cormorants,
divers, and other fishing birds, the otters, seals, and porpoises,
would soon perish also; and lastly, the Fuegian savage, the miserable
lord of this miserable land, would redouble his cannibal feast,
decrease in numbers, and perhaps cease to exist.
JUNE 8TH.--We weighed anchor early in the morning, and left Port
Famine. Captain FitzRoy determined to leave the Strait of Magellan
by the Magdalen channel, which had not long been discovered. Our
course lay due south, down that gloomy passage which I have before
alluded to, as appearing to lead to another and worse world. The wind
was fair, but the atmosphere was very thick; so that we missed much
curious scenery. The dark ragged clouds were rapidly driven over the
mountains, from their summits nearly to their bases. The glimpses
which we caught through the dusky mass were highly interesting:
jagged points, cones of snow, blue glaciers, strong outlines marked
on a lurid sky, were seen at different distances and heights. In
the midst of such scenery we anchored at Cape Turn, close to Mount
Sarmiento, which was then hidden in the clouds. At the base of the
lofty and almost perpendicular sides of our little cove, there was
one deserted wigwam, and it alone reminded us that man sometimes
wandered in these desolate regions. But it would be difficult
to imagine a scene where he seemed to have less claims, or less
authority. The inanimate works of nature--rock, ice, snow, wind, and
water--all warring with each other, yet combined against man--here
reigned in absolute sovereignty.
JUNE 9TH.--In the morning we were delighted by seeing the veil of
mist gradually rise from Sarmiento, and display it to our view. This
mountain, which is one of the highest in Tierra del Fuego, has an
elevation of 6800 feet. Its base, for about an eighth of its total
height, is clothed by dusky woods, and above this a field of snow
extends to the summit. These vast piles of snow, which never melt,
and seem destined to last as long as the world holds together,
present a noble and even sublime spectacle. The outline of the
mountain was admirably clear and defined. Owing to the abundance of
light reflected from the white and glittering surface, no shadows are
cast on any part; and those lines which intersect the sky can alone
be distinguished: hence the mass stood out in the boldest relief.
Several glaciers descended in a winding course, from the snow to the
sea-coast: they may be likened to great frozen Niagaras; and perhaps
these cataracts of blue ice are to the full as beautiful as the
moving ones of water. By night we reached the western part of the
channel; but the water was so deep that no anchorage could be found.
We were in consequence obliged to stand off and on, in this narrow
arm of the sea, during a pitch-dark night of fourteen hours long.
JUNE 10TH.--In the morning we made the best of our way into the open
Pacific. The Western coast generally consists of low, rounded, quite
barren, hills of granite and greenstone. Sir John Narborough called
one part South Desolation, because it is “so desolate a land to
behold;” and well indeed might he say so. Outside the main islands
there are numberless scattered rocks, on which the long swell of the
open ocean incessantly rages. We passed out between the East and West
Furies, and a little further northward there are so many breakers
that the sea is called the Milky Way. One sight of such a coast is
enough to make a landsman dream for a week about shipwreck, peril,
and death; and with this sight, we bade farewell for ever to Tierra
del Fuego.
FOOTNOTES:
[1] The south-westerly breezes are generally very dry. January 29th,
being at anchor under Cape Gregory; a very hard gale from W. by S.,
clear sky with few cumili; temperature 57°, due point 36°, difference
21°. On January 15th, at Port St. Julian: in the morning light winds
with much rain, followed by a very heavy squall with rain,--settled
into heavy gale with large cumili,--cleared up, blowing very strong
from SSW. Temperature 60°, due point 42°,--difference 18°.
[2] As there are no settlements on the Patagonian coast, there are
few means of comparison. Cherry-trees left by the Spaniards at Port
Desire, lat. 48°, still bear fruit, whereas, in Chiloe, on the west
coast, 360 miles further north, I believe they do not succeed.
[3] Journal of the Royal Geographical Society for the years 1830,
1831.
[4] The mean of the maxima of these thirty-seven days was only 55°.5,
and of the minima 45°.3,--the mean range thus being 10°.2. For the
whole sixty-five days, the mean of the maxima was only 51°.7, which
certainly is a very wretched summer, and shows how little bright
sunshine there can be.
[5] This mean must be a little too low, because the whole of August
is not included. I see Von Buch says, “we can hardly assign to
Saltenfiord, Norway (in lat. 67°, or 13° 22′ nearer the pole than
Port Famine) a higher mean temperature than 34°, nor a higher
temperature for the warm month of July than 57°.8.” (Travels through
Norway, p. 123.) Captain King gives as the mean for February, which
probably is the hottest month at Port Famine, only at 51°.1. Some
observations made at the Falkland Islands (2° 13′ north of Port
Famine) which are often quoted, give as the mean for the whole
year 47°.3, and for the summer 53°.1. These results are very much
higher than what I should have anticipated, from the climate of the
neighbouring mainland.
[6] This line is taken from Barton’s Lectures on the Geography of
Plants.
[7] In this wretched climate, subject to such extreme cold, is it not
most wonderful, that human beings should be able to exist unclothed
and without shelter?
[8] Appendix to Flinder’s Voyage, pp. 575 and 584.
[9] Weddell’s Voyage, p. 133.
[10] Geographical Journal, 1830, pp. 65 and 66.
[11] I have reason to believe, that icebergs are formed on the coast
during a part of the year.
[12] Appendix to Back’s Expedition.
[13] Fragmens Asiatiques, vol. ii., p. 386.
[14] Mr. Sulivan, who surveyed this part of Chiloe, informs me, that
between Osorno and Yntales, there are probably many mountains which
rise to a height of nearly 6000 feet. He says he does not recollect
any one summit, which (during January) was not covered with snow.
[15] On January 15th, Yntales, seen from the Northern Chonos Islands,
was entirely covered by snow.
[16] I crossed the Uspallata Pass on April 5th. The height, as given
by Mr. Pentland (Geographical Journal), is 12,454. In the ravines
there were some inconsiderable patches of snow, but the general
surface was quite bare.
[17] The Edinburgh Journal of Natural and Geographical Science,
August, 1830, p. 316.
[18] I have reason to suspect that the snow-line in Chile is subject
to extreme variation. I was told, that during one remarkably dry
and long summer, all the snow disappeared from Aconcagua. Not being
at the time aware of the extraordinary elevation of this mountain
(23,000), I did not closely cross-question my informers. It must
be remembered that even in ordinary summers the sky is generally
cloudless for six or seven months, that no fresh snow falls, and
that the atmosphere is excessively dry. It may be asked whether vast
quantities of snow would not, under this condition of circumstances,
be evaporated? so that it might be _possible_ that all the snow
should disappear from a mountain without the temperature having
risen above the freezing point. Mr. Miers (vol. i., p. 384) says he
passed the Cordillera by the Cumbre Pass on May 30th, 1819, “when
not the smallest vestige of snow was observable in any part of the
Andes.” Yet Aconcagua is in full view in the approach to this pass.
Mr. Miers, in another part (p. 383), makes a general assertion to the
same effect.
[19] See Mr. Pentland’s most interesting paper in the Geograph.
Journal, read March 1835.
[20] Journal of Geograph. Soc., vol. i., p. 165.
[21] For this fact I may quote, as additional authority, Aguerros
Descripcion Historial de la Provincia de Chiloé, 1791, p. 94.
[22] Miers’s Chile, vol. i., p. 415. It is said that the sugar-cane
grew at Ingenio, lat. 32°-33°, but not in sufficient quantity to
make the manufacture profitable. In the valley of Quillota, south of
Ingenio, I saw some large date palm-trees.
[23] The average degree of atmospheric transparency seems to be a
most important element in determining the climate of any place. Dr.
Richardson (Report to Brit. Assoc. for 1836, p. 131) has remarked
that Professor Leslie, from experimenting on the effects of radiation
only in an insular climate, deduced theoretical inferences respecting
the mean temperature of the year, extremely different from the
results obtained under the clear atmosphere of the polar regions.
I apprehend central Chile will bear comparison with any part of
the world for the clearness of its sky, and Chiloe, for one of an
opposite condition: therefore we should not feel surprised, if the
effects of two such opposite climates at first appear and malous.
The remarkable difference in the height of the snow-line, on the
opposite sides of the Himmalaya, has been explained by Humboldt
and Jacquemont, on the same principle: and in a like manner, the
difference between the heights on the Pyrenees and on Caucasus, the
latter mountains being characterized by a climate more excessive,
than that of the former.
[24] In the Alps, Saussure gives 8793 feet as the mean of the lower
limit of the snow-line. At Mont Blanc the glacier of Montanvert is
said (Encyclo. Metropol.) to descend 12,000 feet below the summit of
the mountain, and this will make its base 5160 feet lower than the
line of snow. In Norway (See Von Buch) where a glacier first comes
down to the water’s edge (lat. 67°), it is 3800 below the same line:
in Tierra del Fuego the difference must be very nearly the same as in
the last case.
[25] Hunter’s Voyage to Port Jackson, p. 102.
[26] Mr. Sorrell says, that he once saw an iceberg to the eastward of
South Shetland, with a considerable block of rock lying on it.
[27] I may remark that in the chart, the greater number of the creeks
which receive the glaciers, have crosses drawn in front, which
signify projecting masses of rock. After what we have seen in the
Beagle channel, I suspect that they are detached masses brought down
by the overwhelming force of the glaciers.
[28] Byron’s Narrative of the Shipwreck of the Wager.
[29] Bulkeley’s and Cummin’s Faithful Narrative of the loss of the
Wager. The earthquake happened August 25, 1741.
[30] La Condamine’s Voyage (English translation), p. 24.
[31] I will here put together all the (apparent?) exceptions which
I have met with to the supposed law that erratic blocks are absent
in the intertropical regions of the world. First, in the Bulletin
de la Société Géologique, 1837, p. 234, there is an account of some
erratic blocks near Macao (lat. 22° N.); but as it is distinctly
stated they are all of granite, and the greater number of even the
same coloured variety, as the granitic rock, on which they rest,
the case need not be considered. Secondly, in a late number of the
Madras Journal, Dr. Benza has described some erratic blocks lying
on a plain between the Neilgherries (lat. 12° N.) and Madras. He
states that the foundation-rock of the country is gneiss, “while the
granite clusters are more elevated, and affect either a prismatic
form, or are piled up _one on the other_, like _logging stones_.”
Dr. Benza had the kindness to inform me that these masses are
very large, and that several are piled one upon the other. Again,
Brongniart says (Tableau de Terrains, p. 83), “On cite aussi dans
l’Inde, au pays d’Hyderabad (lat. 17° N.), des blocs _énormes_ de
granite, _amoncelés_ les uns sur les autres” (Deluc neveu). Every
one must draw his own conclusions from these accounts, regarding the
probability of erratic blocks being heaped up, one upon the other,
_like logging stones_. The same doubt likewise partly applies to
the Macao case. With respect to the boulders of Hyderabad, Dr. T.
Christie has distinctly stated (Edin. New Phil. Jour., Oct. 1828, p.
102), that they are _in situ_, and has explained their origin. For
my own part, I cannot forget that whole granitic hills at the Cape
of Good Hope, which, from weathering, have assumed a boulder-like
form, were once described as transported masses. The two next cases
do not properly come under consideration, for they refer to masses
lying in the _valleys_ of lofty mountains. We must not overlook
such accidents as bursting of lakes, earthquakes, and the action
of former coast-lines. Helms, in his Travels (English translation,
p. 45), states he was astonished to find the highest snow-capped
mountains near Potosi (20° N.) covered with a stratum of rounded
granitic stones. He supposes they must have come from Tucuman, which
is several hundred miles distant; yet at p. 55 he says, at Iocalla
(a few leagues only from Potosi), “a mass of granite many miles in
length, rises in huge weather-beaten rocks:” the whole account is to
me quite unintelligible. Lastly, M. Gay (Annales des Sciences, 1833)
describes granitic boulders within the valley of Cauquenes (lat.
33°-34° S.), in the Cordillera. I visited this place: the boulders
and pebbles are not large, and those beyond the mouth of the valley
are small. The case did not appear to me nearly so extraordinary as
it seems to have struck M. Gay. I cannot agree with his assertion
that this rock is not found in that part of the Cordillera: but this
is a subject which I shall discuss in a future work.
[32] The absence of great embedded fragments in the formations of the
secondary epoch, when we know that the climate was of a more tropical
character, is a fact of the same kind.
[33] Anniversary Address to the Geological Society, Feb. 19, 1836, p.
30; and Principles of Geology, vol. i., p. 269, and vol. iv., p. 47,
fifth edition.
[34] It is in the southern hemisphere that we find elephants,
rhinoceroses, hippopotomuses, and lions, as far south as lat. 34°
35′. In South America the jaguar occurs in 42°, and the puma in 53°.
[35] Geographical Journal. Capt. King uses these words when alluding
to the case in Sir G. Eyre’s Sound, which I have more fully described
from the information of Mr. Bynoe.
[36] In the fourth and subsequent editions.
[37] Wrangel’s Voyage in the Icy Sea in the years 1821, 1822, and
1823. Edited by Professor Parrot, of Dorpat, Berlin, 1826.
[38] Dr. Fleming first brought this notion forward in two papers
published in the Edinburgh Philosoph. Journ. (April, 1829, and Jan.
1830). He adduces the case of allied species of the bear, fox, hare,
and ox, living under widely different climates.
[39] Since writing the above, I have been much interested by reading
an account by Professor Esmark, which proves that formerly, glaciers
in Norway descended to a lower altitude than at present; and
therefore, that they came down to the level of the sea in a lower
latitude. This, according to generally-received ideas, would indicate
a colder climate, and so it was considered to do by Professor Esmark;
for he argues from it in favour of Whiston’s hypothesis, that the
“earth in its aphelion was covered with ice and snow.” Professor
Esmark describes a glacier-dike, in lat. 58° 57′, as “lying close
to the level of the sea, in a district, where you find only a few
heaps of perpetual snow in the hollows of the mountains.” He says,
“Not only the dike itself, but the whole horizontal surface, exhibits
proofs that there has been a glacier here, for the plain exactly
resembles those which I found adjoining the glaciers presently
existing between Londfiord and Lomb.” (See Ed. New Phil. Journal, p.
117, October 1826.) These facts afford a very strong and admirable
confirmation of the view, that the climate of Europe has been
gradually changing, from a character resembling that of the southern
hemisphere, to its present condition. For on this hypothesis, we
might have anticipated, that proofs would have been discovered, that
glaciers formerly descended to a lower altitude than they now do;
and yet, that the organic remains of that epoch, instead of a former
period of refrigeration, would have indicated a climate of a more
tropical character;--a conclusion, which may be deduced from plain
geological evidence.
[40] See Humboldt, Fragmens Asiatiques, vol. ii., pp. 385-395.
[41] See some remarks by Dr. Buckland on the similarity of this
formation with the deposits so commonly found over a great part of
Europe. Appendix to Beechey’s Voyage, p. 609.
[42] Ossemens Fossiles, vol. i., p. 151.
[43] Under these circumstances of slow decomposition, the surrounding
deposits would probably be impregnated with much animal matter; and
thus the peculiar odour perceived in the neighbourhood of the strata
containing fossil bones at Eschscholtz Bay, may be accounted for. See
Appendix to Beechey’s Voyage.
[44] With respect to the possibility of even ice accumulating at
the bottom of the sea, I shall only refer to the following passage
taken from the English translation of the _Expedition to the East
Coast of Greenland, by Captain W. Graah, Danish Royal Navy_. “Nor
is this the only danger to be apprehended: the ice off this blink,
even to a considerable distance from it, being said to shoot up
from the bottom of the sea in such a manner, and in such masses,
as in many years to make it utterly impassable. How to account for
the phenomenon to which I have just adverted I know not, unless by
supposing that the bottom of the sea itself is hereabouts like the
dry land covered with a thick crust of ice. But whether this crust
is formed upon the spot, or is the remains of icebergs and the heavy
drift-ice frozen to the bottom during severe winters, or a portion of
the land-ice, which loaded with stones and fragments of the crumbling
hill has protruded itself into the sea, is a problem impossible,
perhaps to solve.” Again he says: “We passed it without any accident,
and without having observed any thing of that upheaving of the ice
off it, to which allusion has been made, though the fact of its
occurrence cannot be doubted, the very name of the place, Puisortok,
being thence derived.” It seems fully established on excellent
testimony (see Journ. of Geograph. Soc., vol. v., p. 12, and vol.
vi., p. 416; also a collection of notices in Edinburgh Journal of
Nat. and Geograph. Soc., vol. ii., p. 55), that fresh-water rivers
in Russia and Siberia, and even in England, often freeze at the
bottom, and that the flakes of ice when they rise to the surface,
often “bring with them large stones.” All that seems to be required
in producing ground-ice, is, that there should be sufficient movement
in the fluid, so that the whole is cooled down to the freezing point,
and then the water _crystallizes_, wherever there is a point of
attachment.
[45] In New Zealand, before the introduction of the potato, the root
of the fern was consumed in large quantities. At the present day I
should think Tierra del Fuego was the only country in the world,
where a cryptogamic plant afforded a staple article of food.
[46] Captain FitzRoy informs me that in April (our October) the
leaves of those trees which grow near the base of the mountains
change colour, but not those in the more elevated parts. I remember
having read some observations showing, that in England the leaves
fall earlier in a warm and fine autumn, than in a late and cold one.
This change in the colour being retarded in the more elevated and
therefore colder situations, must be owing to the same general law of
vegetation. The trees of Tierra del Fuego during no part of the year
entirely shed their leaves.
[47] I believe I must except one alpine Haltica, and a single
specimen of a Melasoma. Mr. Waterhouse, who was good enough to look
at my collection from this place, tells me, that of the Harpalidæ
there are eight or nine species,--the forms of the greater number
being very peculiar; of Heteromera, four or five species; of
Rhyncophora six or seven; and of the following families one species
in each: Staphylinidæ, Elateridæ, Cebrionidæ, Melolonthidæ. The
species in the other orders, were even fewer. In all the orders, the
scarcity of the individuals was even more remarkable than that of the
species.
[48] I have reason to believe that many of these animals are
exclusively confined to this station.