The Forms of Water in Clouds and Rivers, Ice and GlaciersTyndall, John
Science
The Forms of Water in Clouds and Rivers, Ice and Glaciers
Tyndall, John
Clouds; Glaciers; Ice; Rivers; Water
[J] M. Agassiz, however, reports a case of the kind upon the glacier
of the Aar.
[Illustration: STRUCTURE AND BEDDING ON ALETSCH GLACIER.]
461. Here day after day added to the conviction that the bedding and
the structure were two different things. Still day after day passed
without revealing to us the final proof. Surely we have not let our
own ease stand in the way of its attainment, and if we retire baffled
we shall do so with the consciousness of having done our best.
Yonder, however, at the base of the Matterhorn, is the Furgge glacier
that we have not yet explored. Upon it our final attempt must be made.
462. We get upon the glacier near its end, and ascend it. We are soon
fronted by a barrier composed of three successive walls of névé, the
one rising above the other, and each retreating behind the other. The
bottom of each wall is separated from the top of the succeeding one
by a ledge, on which threatening masses of broken névé now rest. We
stand amid blocks and rubbish which have been evidently discharged
from these ledges, on which other masses, ready apparently to tumble,
are now poised.
463. On the vertical walls of this barrier we see, marked with the
utmost plainness, the horizontal lines of stratification, while
something exceedingly like the veined structure appears to cross the
lines of bedding at nearly a right angle. The vertical surface is,
however weathered, and the lines of structure, if they be such, are
indistinct. The problem now is to remove the surface, and expose the
ice underneath. It is one of the many cases that have come before
us, where the value of an observation is to be balanced against the
danger which it involves.
464. We do nothing rashly; but scanning the ledges and selecting a
point of attack, we conclude that the danger is not too great to
be incurred. We advance to the wall, remove the surface, and are
rewarded by the discovery underneath it of the true blue veins. They,
moreover, are vertical, while the bedding is horizontal. Bruce, as
you know, was defeated in many a battle, but he persisted and won at
last. Here, upon the Furgge glacier, you also have fought and won
your little Bannockburn.
[Illustration: STRUCTURE AND BEDDING ON FURGGE GLACIER.]
465. But let us not use the language of victory too soon. The
stratification theory has been removed out of the field of
explanation, but nothing has as yet been offered in its place.
§ 65. _Relation of Structure to Pressure._
466. This veined structure was first described by the distinguished
Swiss naturalist, Guyot, now a resident in the United States. From
the Grimsel Pass I have already pointed out to you the Gries glacier
overspreading the mountains at the opposite side of the valley of the
Rhone. It was on this glacier that M. Guyot made his observation.
Public-domain text, read in full here on John Shaqi.
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