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56 DETEITUS-LADEN BERGS.
tudes examples of the kind ai'e known to be frequent. But the comparatively
small number of bergs which aiforded evidence of their having been reversed or
tilted over on their sides suggests an explanation, namely, that so long as icebergs
are afloat, the great preponderance in bulk of the submerged portion in the
generality of cases renders the effects of wasting above water, or the force exercised
by winds and waves even when at a maximum, powerless in disturbing
their centres of gravity. Although soundings taken both on the east and west
coasts of Greenland clearly indicate that, for distances varying from five to thirty
miles from the shore-line, the depth is sufficiently moderate to admit of the
grounding of the larger bergs, there cannot be a doubt that the percentage of
bergs thus an-ested in their transit is so trifling in comparison with those that
drift up to the head of Baffin’s Bay as to render the cases exceptional. Again,
those cases are still more exceptional in which, when large bergs take the
ground, they are subjected to impact of bergs equalling or nearly equalling them
in dimensions. In the first place, the number, although very gi’eat in this part
of the ocean, is insignificant in relation to the area over which they are distributed
; and in the second, the very nature of the current by which they are
home onwards renders such an occurrence extremely rare, since disparity in the
rates of progression of different bergs can only result from disparity in their
masses and consequent extent of immersion. In other words, the smaller the
berg, the more rapidly would it drift; and hence in the event of a berg overtaking
another, and coming into collision with it, the one most likely to he overturned
or crushed would be the smaller, and not the larger of the two.
In the event of a continuous field of pack-ice being drifted against stranded
bergs, the accumulative force would suffice to overturn or even crush the largest
met with in these latitudes. Such an event, in all probability, occurred in the
case of the grounded berg alluded to by me as having been seen on the evening
of the 31st of July; and I therefore doubly regret that an untoward accident of
weather prevented us from witnessing a collision the effects of which must have
been so stupendous. Although I was unable to obtain information with regard
to the characters of the bergs met with beyond the immediate coast-line from our
Danish friends at Goodhaab and Julianshaab, the opinion I have expressed,
regarding the extreme rarity of examples in which drift or detritus is observable,
is fuUy home out by Mr. Tayler, an English gentleman who has resided in
EEVEESED BEEGS. 57
South Greenland for seven years, and has had many opportunities of arriving at
a correct knowledge on the subject. He has informed me that not one berg in
a thousand of those which drift along the coast presents the appearances in
question. To this statement I would append the inference I draw from it,
namely, that not one berg in a thousand of those met with below the 64th degree
of latitude on the western side of Greenland comes under the influence of those
forces which are necessary to alter its centre of gravity to any material extent,
I am far from asserting that, where boulders or detritus occur, the surface
occupied by them necessarily represents the original base of the mass before it
was projected from its parent glacier; hut, judging from the appearance of
the greater number of large bergs, I think it may be accepted as true that the
direction of their upper and under surfaces has not been altered since they constituted
part and parcel of the glacier, and that the presence of foreign matters,
such as stones and gravel, in most cases is due to their having grounded after
being detached, and floating away again only when reduced sufficiently in hulk, by
the temperature present, both above and below water. I t is also well known that
bergs may receive deposits or even boulders whilst afloat by coming into contact
ivith overhanging rock-sm-faces; but these examples are obviously too exceptional
and rare to affect the present question.
I have already noticed how constantly the submerged portion of bergs
spreads in a lateral direction, thereby augmenting the firmness of their bases;
and coupling all these facts together, I think it becomes evident we must look
for the force capable of coping with masses of matter of such immense volume
in that crowding together of bergs which only takes place in higher latitudes,
precisely in the same m.aiirL6r that the masses of ordinary pack-ice are crushed
and turned over in every possible way by masses of equal proportions with
themselves when closely pressed together in drifting fields. In the case of a berg
drifting along in shoal water, this extraordinary force is not necessary to
produce the result, inasmuch as the momentum of the mass itself, or the leverage
exercised by winds or currents, would suffice to tilt it over on its becoming
stranded. There is ample proof of this process taking place, inasmuch as in
shallow water bergs may frequently be seen laden with gravel or detritus,
and exhibiting distinct evidence of having been reversed or tilted over. On the
other hand, nothing can demonstrate more conclusively the insignificance of the