A Voyage of Discovery and Research in the Southern and Antarctic Regions/Volume 2/Appendix 4
APPENDIX, No. IV.
GEOLOGICAL REMARKS ON THE ANTARCTIC CONTINENT AND SOUTHERN ISLANDS, BY ROBERT McCORMICK, ESQ., SURGEON OF H.M.S. EREBUS.
The earth's crust, as we approach towards the pole in the southern hemisphere, presents, in a remarkable degree, the most striking indications of the vast subterranean fires pent up within it, and, as we now find, having vents in both the frigid zones: the volcano of Jan Mayen, actively burning within the Arctic circle; and Mount Erebus, rising from the lofty mountain range of the newly-discovered continent of Victoria, to an altitude of more than 12,000 feet above the Antarctic Ocean, and sending forth its smoke and flame to the height of 2000 feet above its crater, the centre of volcanic action in those regions of eternal snow.
On our first voyage south, after sailing from the River Derwent, Tasmania, on the 12th of November, 1840, we proceeded to the Auckland Group, and Campbell Island, the former situated in about the latitude of 51° S., and longitude 166° E., and the latter in the 53rd degree of latitude. Both are of igneous formation, being chiefly constituted of basalt and greenstone, forming hill ranges, nowhere exceeding an altitude of 2000 feet. The basalt frequently occurs in the prismatic form. At Deas Head, a promontory 300 feet in height, in Auckland Island, these prismatic pillars were highly magnetic.
Pebbles of quartz and agate occur amongst the shingle on the beach at Campbell Island, and some traces of limestone; the only indication of the sedimentary class of rocks which we met with after our departure from the Australian Lands.
Auckland Island is thickly wooded, with trees belonging principally to the Myrtaceæ, Veronica, Araliaceæ, and Epacrideæ, forming dense thickets, from twenty to thirty feet in height, almost impenetrable, and impervious to the sun's rays. The alluvium beneath is clothed with ferns and cryptogamic plants, growing in rank luxuriance, the decaying trunks of fallen trees being completely shrouded within lichens and mosses. The soil is generally good, composed of a rich black mould, in many places of considerable depth—the result of decomposition of the volcanic debris and a redundant vegetation—so highly productive, that it would render the islands well worth the attention of colonists.
In some of the valleys, the bright golden yellow blossoms of a species of Asphodeleæ[1] are so thickly grouped together as to form the most beautiful lively-looking patches, spread out like a carpet of gold, as if to relieve the sombre shade of the woods.
The climate, although somewhat humid and subject to heavy squalls, is nevertheless very healthy, and the harbours are excellent.
The common hog, introduced originally by some whaling ship, runs wild in the woods; and from the extent of soil rooted up by these animals in search of the roots of an umbelliferous plant, on which they feed, and which gives to their flesh a peculiar flavour, they must be tolerably numerous, although I saw only two during my rambles, the thick cover affording them ample means of shelter.
The birds are few in number, both in species and individuals, and are all belonging to New Zealand species; the Tui (Meliphaga concinnata) and Korimaku (Certhiæ olivaceæ) being the chief choristers of the woods: these, with two or three other small species of the Meliphagidae, and a hawk, a small parrakeet, and the Pihoihoi, or Ground Lark (Anthus Novas Seelandiæ), were all the land birds met with.
The water birds consisted of a duck (Anas superciliosa), a Merganser (Mergus Australis), a penguin (Aptenodytes antipodes), a snipe found in the high grass near the bay, and two species of gulls (Larus littoreus, and L. Novæ Hoilandiæ,) frequented all the bays in considerable numbers.
In Campbell Island, situated not much further south, and although less wooded than Auckland, having many of its valleys overgrown with underwood, and the general character of the vegetation similar, I did not meet with a single land bird.
These islands appear to be the favourite breeding-places of the Albatross (Diomedea exulans), and during our stay in the months of November and December they were so busily employed in the work of incubation, as to allow themselves to be caught, without making an effort to escape. It is an amusing scene to watch a group of these birds, a dozen or more, assembled together on the side of a hill, grotesquely waddling about, selecting their mates; this being settled, they disperse, and each pair fix upon a spot for the nest. This consists of a mound of soil, intermingled with withered leaves and grass, the average dimensions of which I found to be eighteen inches in height, twenty-seven inches in diameter at the top, and six feet at the base. The albatross, like the petrels, only lays one egg, of a white colour, averaging seventeen ounces in weight. In one instance, only, I found two eggs in the same nest (both of the full size, and one of them unusually elongated in its longest diameter), although I must have examined at least a hundred nests. The snow-white head and neck of the albatross appearing above the grass when sitting on its nest, betrays its situation at a considerable distance. When forced off its egg, it makes a resolute defence, snapping the mandibles of its beak sharply together in defiance. I have frequently found it sleeping in the day-time, with its head under its wing. Its greatest enemy is the Lestris antarcticus, a fierce raptorial gull, which is constantly on the watch for the bird quitting its nest, when it will instantly pounce down upon and devour the egg. So well is the albatross aware of the propensity of its enemy, that it will snap its beak loudly whenever it observes this rover hovering overhead. Three or four species of petrel were breeding in the holes of the cliffs overhanging the bay.
The oceanic birds met with, after our departure from Campbell Island, were albatrosses, petrels, and penguins. Those most frequently seen were Diomedea exulans, D. fuliginosa, Procellaria gigantea, P. capensis, P. pelagica, P. Cookii, P. vittata, and P. marina. Two species of seaweed were frequently passed floating on the surface of the sea, a Laminaria, and the Macrocystis pyrifera; the latter was met with as far south as the sixty-fourth degree.
On crossing the Antarctic circle on the new year's day, the White Petrel (Procellaria nivea), the sure harbinger of ice, first made its appearance; it is the most elegant and beautiful species of all the petrels, and delights to be in the vicinity of ice; for during the summer season it is scarcely ever seen north of the Antarctic circle. It will often, after gracefully skimming the surface of the ocean in search of shrimps and small fishes, elevate its flight, and amuse itself in making rapid circles round the ship. Whilst going through their various evolutions, I have often succeeded in obtaining specimens by shooting them from the deck to windward, so as to secure their falling on board.
On the 11th of January, 1841, in latitude about 71° S., and longitude 171° E., the Antarctic Continent was first seen, the general outline of which at once indicated its volcanic character; rising steeply from the ocean in a stupendous mountain range, peak above peak, enveloped in perpetual snow, and clustered together in countless groups resembling a vast mass of crystallisation, which, as the sun's rays were reflected on it, exhibited a scene of such equalled magnificence and splendour as would baffle all power of language to portray or give the faintest conception of. One very remarkable peak, in shape like a huge crystal of quartz, rose to the height of 7867 feet; another to 9096; and a third to 8444 feet above the level of the sea. From these peaks ridges descended to the coast, terminating abruptly in bold capes and promontories, whose steep escarpments, affording attachment to neither ice nor snow, alone showed the jet black lava or basalt which reposed beneath the mantle of eternal frost.
On the following day I landed on a small island (Possession Island), lying a little to the eastward of the main land in latitude 71° 56′ S., and longitude 171° 7′ E., which I found to be composed of a volcanic conglomerate, vesicular lava, and basalt, containing imbedded crystals, and rising to the height of about three hundred feet.
As we pulled round the island in the boat, we passed a beautiful little recess in the prismatic columns of basalt, presenting a miniature resemblance to Fingal's Cave in Staffa. The spot on which we effected a landing was ice-girt, between which and the foot of the hill a colony of penguins (a new species) had formed a rookery, and were busily engaged rearing their young. They were in such countless multitudes, that it was with difficulty we could make our way through them; and their clamour baffled all description. The young were covered with down, but no eggs were found. The spot on which they were breeding was spongy and elastic, forming a rich bed of guano of great depth, the accumulation of ages. I shot a Lestris antarcticus, flying overhead, which was of smaller size, and much greyer about the head and neck than the Auckland specimens.
On the 28th, in latitude 77° 31′, and longitude 167° 1′, the burning volcano (Mount Erebus) was discovered, covered with ice and snow from its base to its summit, from which a dense column of black smoke towered high above the numerous other lofty cones and crateriform peaks with which this extraordinary land is studded, from the seventy-second to the seventy-eighth degree of latitude. Its height above the level of the sea is 12,367 feet; and Mount Terror, an extinct crater adjoining it, which has, doubtless, once given vent to the fires beneath, attains an altitude little inferior, being 10,884 feet in height, and ending in a cape, from which a vast barrier of ice extended in an easterly direction, checking all further progress south. This continuous perpendicular wall of ice, varying in height from 200 to 100 feet, its summit presenting an almost unvarying level outline, we traced for about 300 miles, when the pack-ice obstructed all further progress. Soundings were obtained within a quarter of a mile of it; in 318 fathoms on a bottom of green mud.
This appeared to be the favourite haunt of the White Petrel; an Antarctic Lestris occasionally intruding on its icy domain: whilst, reposing on the ice, were numerous penguins and seals, and, in the open water, whales were spouting in all directions, chiefly the "Finner," and a beautiful piebald grampus, or small whale, spotted reddish brown and white. On our return we sighted Balleny Islands, in lat. 68°, and long. 169°; they present the same volcanic outline as the rest of the land to the southward.
On the second voyage south, we took our departure from the Bay of Islands, New Zealand, in the month of November, 1841, but did not meet with any land; having been beset for many weeks in the pack-ice, and our progress towards the Pole again checked by the Barrier, which we made more to the eastward than last season, in lat. 78° 10′ S., being the highest latitude we attained. On our return we doubled Cape Horn on the 2nd, and arrived at Port Louis, East Falkland Island, on the 6th of April 1842.
Prior to our third and last voyage across the Antarctic circle, we visited—
HERMITE ISLAND.
This island lies about ten miles north-west of Cape Horn, near the latitude of 56° S., and, with the exception of that celebrated cape, is the southernmost of those Fuegian Isles in which the vast continent of the New World terminates to the southward. It is of irregular form, deeply indented by bays and coves; its shores bold and steep, surmounted by conical peaks, that of Mount Kater being 1742 feet above the sea. Its greatest length is from east to west, being twelve miles. The geological structure is very simple, being entirely of plutonic origin: syenitic greenstone, resting on a basis of granite, with here and there some quartzose and felspathic rocks. Having ascended all the peaks bounding St. Martin's Cove, I found them composed of syenitic greenstone, with the exception of Forster's Peak, which is capped with a hard, fine-grained, dark greenstone; and the same kind of rock also occurs scattered about in masses over the western ridge, and in a cleft at the base of Mount Kater. The greenstone has polarity, and is highly magnetic in places.
In an excursion I made across the central ridge of hills to the northern shore of the island, I found the nest of the Antarctic Goose (Anas antarctica), containing seven eggs, about the size and colour of a duck's; the nest, which was formed of down from the breast of the bird, was concealed amongst grass in the bank skirting the beach, near a Fuegian hut; from which two of the natives made their appearance, and expressed by signs their great desire for the eggs; but on my shooting the goose, and leaving it in their possession, they seemed quietly enough disposed to receive it as an equivalent. This circumstance enabled me very satisfactorily to account for the great scarcity of birds in this island, as their eggs are doubtless all devoured by the Fuegians as soon as laid. Near the wigwam I also shot a very beautiful species of Polyborus, the only one of the kind I obtained on the island.
In an excursion to the southernmost point of the island, Cape Spencer, to the summit of which I ascended, my course lay over a ridge of granite, commencing at St. Joachim's Cove (a small white sandy beach), and extending to the base of Cape Spencer, which is composed of the same rock.
Along the ridge enormous blocks of this rock are scattered about in the wildest confusion; some of these masses were traversed by veins of a dark green, compact greenstone, varying from three inches to three feet in breadth. The summit of Cape Spencer is syenitic greenstone, in broken fragments piled one upon another, and enclosing a crater about two hundred feet in depth; its bottom was occupied by a lake, frozen over on its north side. This crater is about a mile in circumference, its greatest diameter being from north to south. Its highest part is on the west side, forming a very narrow ledge, along which I proceeded to the southernmost precipice overhanging the ocean. This spot commands a fine extensive prospect all round, and the sun shining forth from a clear blue sky rendered every object distinctly visible to a great distance. To the north appeared the snow-capped mountains of Tierra del Fuego, and its many isles. In the S. W. quarter, the Diego Ramirez rocks were faintly delineated above the horizon, like a few small hummocks.
Cape Horn stood boldly forth to the S.E., and the surface of the vast ocean was spread out beneath me to the south. Whilst surveying the scene around me, the solitude of which was broken only by the Polyborus or Fuegian Hawk hovering overhead, my eye suddenly rested upon half a score of the dusky forms of the Fuegians, wending along one of their tracks in the valley beneath in single file, in the direction of their wigwam, at Joachim's Cove; returning in all probability from an excursion in search of limpets along the ledges of rocks bounding the coast. Elevated as I was above them, and sitting amongst piles of rocks, I did not escape their keen, quick eyes; for I observed them, more than once, come to a halt to reconnoitre my position.
LOUIS PHILIPPE LAND,
Off which the Expedition was so long beset amid pack-ice and a chain of bergs, in the last attempt to penetrate south, is, like other Antarctic lands, apparently of igneous formation. The first portion of it that we made appeared like a vast wreath of snow banked up against the horizon, extending from W. to S.E. by S. The central and highest part might be estimated at about 2000 feet above the level of the sea; sloping gradually down on either side to a low point. The coast-line alone, where bergs had been separated, presented an uneven surface. The highest point was marked by the tops of two black peaks, appearing through the mantle of snow, which enveloped the rest of the land.
A small snow-clad islet lies off its western extremity, about a league distant; and as we coasted along the southern portion, we passed a chain of six low islands, partially covered with snow, the exposed rock having the appearance of lava or basalt.
We next passed a large opening in the land, which had the appearance of a strait, bounded on the right by high, bold, black cliffs, which stood out in strong relief against the snow, with which the low left side was covered, sloping down towards the farthest visible extremity, where the strait appeared to curve round. The entrance is from four to five leagues in breadth, having a conical island in its centre, terminating in a crateriform peak, of black lava-like looking rock, nearly bare of snow. A large colony of penguins had established their rookery at its base, it being the breeding season. Cormorants, black-backed gulls, terns, white petrel, and the lestris antarcticus, were breeding there; and doubtless, also, that anomaly amongst birds, the Chionis, the eggs of which form such a desideratum in ornithology; and I regret much not having had an opportunity of landing in search of them. To the S.W. of this strait, we discovered more land, commencing with a low black ledge, singularly marked by waved lines, running south, resembling streams of lava, and the only portion of the land without a vestige of snow. From this, bold and rugged cliffs arose, covered with snow, their steep, black escarpments only appearing through it, the shores being girt by an icy barrier. The extremity of the land seen terminated in a bluff, black-looking headland, bearing W. by S. I obtained a mass of hornstone, imbedded in a layer of blue mud, from a piece of ice, alongside which we watered the ship. As I had no opportunity of landing for specimens, I was in the habit of examining the stomachs of most of the birds which I shot and preserved for the Government Collection; and found the penguins my best geological collectors, for their crops were frequently filled with pebbles; more especially the large species, Aptenodytes antarctica. In one of these individuals I found upwards of a pound of small fragments of rocks; comprising, basalt, greenstone, porphyry, granite, vesicular lava, quartz, scoriæ, and pumice; but none of them ever brought me a vestige of aqueous rocks,—all were volcanic,—and such the appearance of the Antarctic lands, even at a distance, would proclaim them to be.[2] We saw three species of penguins within the Antarctic circle. The larger kind, "Aptenodytes antarctica," attains a great size. I preserved one, weighing seventy-five pounds. It is a scarce bird, generally met with singly; and I have never seen more than two or three together; whilst the two smaller species congregate in immense numbers. I know not to what cause we can assign this very remarkable paucity of individuals in the larger species.
After reaching the latitude of 71° 30′, in the meridian of 15° west, we returned to the Cape of Good Hope, on the 4th of April, 1843; thus completing the circumnavigation of the globe.
- ↑ Chrysobactron Rossii. Flora Antarctica, vol. I. p. 72., plates with notes.
- ↑ As the absence of the sedimentary class of rocks may appear unfavourable to the existence of an Antarctic continent, it must be understood, that my remarks have reference only to the land seen, and that merely the coast-line. Aqueous formations may exist in the interior, beneath the covering of ice and snow; but, it is not the less remarkable, that the land, generally, in the Antarctic regions should present so strikingly the volcanic character. Whilst within the Arctic circle, although the trappean rocks are not excluded, which the active volcano of Jan Mayen itself attests; yet, the sedimentary formations have a vast preponderance over the igneous. Spitzbergen and its islands forming the northernmost known land, which I had myself an opportunity of examining, when belonging to H.M.S. Hecla, in the last attempt to reach the North Pole, present not a vestige of lava or basalt, but are constituted chiefly of the primary and transition rocks.