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.* 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
* I n th e A lp s , S a iis su re g ives 8 7 9 3 fe e t a s th e m e a n o f th e low e r
lim it o f t h e sn ow -lin e . A t M o n t B la n c th e g la c ie r o f M o n ta n v e r t is s a id
(E n c y c lo . M e tro p o l.) to d e s c e n d 12,000 fe e t b e low th e sum m it o f th e
m o u n ta in , a n d tliis w ill m a k e its b a s e 5 1 6 0 fe e t low e r th a n th e lin e o f
sn ow. I n N o rw a y (S e e V o n B u c h ) w h e r e a g la c ie r firs t comes d ow n
to th e w a te r ’s ed g e ( la t . 6 7 ° ) , i t is 3 8 0 0 b e low th e same lin e : in T i e r r a d e !
F u e g o th e d iffe re n c e m u s t b e v e ry n e a rly th e s am e a s in th e la s t ca se .
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 i t :
he was knocked over and over but not hurt; and the boats,
though thrice lifted on high and let faU 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
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