They Will Imagine Smooth Conical Hills Of A
Bright Red Colour, With Their Summits Generally Truncated,
Rising Separately Out Of A Level Surface Of Black Rugged Lava.
A Principal Mound In The Centre Of The Island, Seems The
Father Of The Lesser Cones.
It is called Green Hill:
Its
name being taken from the faintest tinge of that colour,
which at this time of the year is barely perceptible from the
anchorage. To complete the desolate scene, the black rocks
on the coast are lashed by a wild and turbulent sea.
The settlement is near the beach; it consists of several
houses and barracks placed irregularly, but well built of
white freestone. The only inhabitants are marines, and some
negroes liberated from slave-ships, who are paid and victualled
by government. There is not a private person on the
island. Many of the marines appeared well contented with their
situation; they think it better to serve their one-and-twenty
years on shore, let it be what it may, than in a ship; in this
choice, if I were a marine, I should most heartily agree.
The next morning I ascended Green Hill, 2840 feet high,
and thence walked across the island to the windward point.
A good cart-road leads from the coast-settlement to the
houses, gardens, and fields, placed near the summit of the
central mountain. On the roadside there are milestones, and
likewise cisterns, where each thirsty passer-by can drink
some good water. Similar care is displayed in each part of the
establishment, and especially in the management of the
springs, so that a single drop of water may not be lost: indeed
the whole island may be compared to a huge ship kept
in first-rate order. I could not help, when admiring the
active industry, which had created such effects out of such
means, at the same time regretting that it had been wasted on
so poor and trifling an end. M. Lesson has remarked with
justice, that the English nation would have thought of making
the island of Ascension a productive spot, any other
people would have held it as a mere fortress in the ocean.
Near this coast nothing grows; further inland, an occasional
green castor-oil plant, and a few grasshoppers, true
friends of the desert, may be met with. Some grass is scattered
over the surface of the central elevated region, and the
whole much resembles the worse parts of the Welsh mountains.
But scanty as the pasture appears, about six hundred
sheep, many goats, a few cows and horses, all thrive well on
it. Of native animals, land-crabs and rats swarm in numbers.
Whether the rat is really indigenous, may well be doubted;
there are two varieties as described by Mr. Waterhouse;
one is of a black colour, with fine glossy fur, and
lives on the grassy summit, the other is brown-coloured and
less glossy, with longer hairs, and lives near the settlement
on the coast. Both these varieties are one-third smaller than
the common black rat (M. rattus); and they differ from it
both in the colour and character of their fur, but in no
other essential respect. I can hardly doubt that these rats
(like the common mouse, which has also run wild) have
been imported, and, as at the Galapagos, have varied from
the effect of the new conditions to which they have been
exposed: hence the variety on the summit of the island
differs from that on the coast. Of native birds there are
none; but the guinea-fowl, imported from the Cape de
Verd Islands, is abundant, and the common fowl has likewise
run wild. Some cats, which were originally turned out
to destroy the rats and mice, have increased, so as to become
a great plague. The island is entirely without trees,
in which, and in every other respect, it is very far inferior
to St. Helena.
One of my excursions took me towards the S. W. extremity
of the island. The day was clear and hot, and I saw the
island, not smiling with beauty, but staring with naked
hideousness. The lava streams are covered with hummocks, and
are rugged to a degree which, geologically speaking, is not
of easy explanation. The intervening spaces are concealed
with layers of pumice, ashes and volcanic tuff. Whilst passing
this end of the island at sea, I could not imagine what
the white patches were with which the whole plain was
mottled; I now found that they were seafowl, sleeping in such
full confidence, that even in midday a man could walk up
and seize hold of them. These birds were the only living
creatures I saw during the whole day. On the beach a great
surf, although the breeze was light, came tumbling over
the broken lava rocks.
The geology of this island is in many respects interesting.
In several places I noticed volcanic bombs, that is, masses of
lava which have been shot through the air whilst fluid, and
have consequently assumed a spherical or pear-shape. Not
only their external form, but, in several cases, their internal
structure shows in a very curious manner that they have revolved
in their aerial course. The internal structure of one
of these bombs, when broken, is represented very accurately
in the woodcut. The central part is coarsely cellular, the
cells decreasing in size towards the exterior; where there
is a shell-like case about the third of an inch in thickness,
of compact stone, which again is overlaid by the outside
crust of finely cellular lava. I think there can be little
doubt, first that the external crust cooled rapidly in the state
in which we now see it; secondly, that the still fluid lava
within, was packed by the centrifugal force, generated by
[picture]
the revolving of the bomb, against the external cooled
crust, and so produced the solid shell of stone; and lastly,
that the centrifugal force, by relieving the pressure in the
more central parts of the bomb, allowed the heated vapours
to expand their cells, thus forming the coarse cellular mass
of the centre.
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