Science in Short ChaptersWilliams, W. Mattieu (William Mattieu)
Science
Science in Short Chapters
Williams, W. Mattieu (William Mattieu)
Science
The same in Scandinavia. The Storelv of the Jostedal is fed by the
melting of the Krondal, Nygaard, Bjornestegs, and soldal glaciers. It
has filled up a branch of the deep Sogne fjord, forming an extensive
fertile plain at the mouth of its wild valley, and is depositing
another subaqueous plain beyond, while the moraines of the glaciers
are but inconsiderable and comparatively insignificant heaps of
loose boulders, spread out on the present and former shores of the
above-named glaciers, which are overflows from one side of the great
_nevé_, the Jostedal Sneefond. All of these glaciers flow down small
lateral valleys, spread out, and disappear in the main valley, which
has now no glacier of its own, though it was formerly glaciated
throughout.
What must have been the condition of this and the other great
Scandinavian valleys when such was the case? To answer this question
rationally we must consider the meteorological conditions of that
period. Either the climate must have been much colder, or the amount of
precipitation vastly greater than at present, in order to produce the
general glaciation that rounded the mountains up to a height of some
thousands of feet above the present sea-level. Probably both factors
co-operated to effect this vast glaciation, the climate colder, and the
snow-fall also greater. The whole of Scandinavia, or as much as then
stood above the sea, must have been a _nevé_ or sneefond on which the
annual snow-fall exceeded the annual thaw.
This is the case at present on the largest _nevé_ of Europe, the 500
square miles of the great plateau of the Jostedals and Nordfjords
Sneefond, on all the overflowing _nevé_ or snow-fields of the Alps
above the snow-line; over the greater part of Greenland; and (as the
structure of the southern icebergs prove) everywhere within the great
Antarctic ice barrier.
What, then, must happen when the snow-line comes down, or nearly down,
to the sea-level? It is evident that the out-thrust glaciers, the
overflow down the valleys, cannot come to an end like the present Swiss
and Scandinavian glaciers, by the direct melting action of the sun.
They may be somewhat thinned from below by the heat of the earth, and
that generated by their own friction on the rocks, but these must be
quite inadequate to overcome the perpetual accumulation due to the
snow-fall upon their own surface and the vast overflow from the great
snow-fields above. They must go on and on, ever increasing, until they
meet some new condition of climate or some other powerful agent of
dissipation—something that can effectively melt them.
This agent is very near at hand in the case of the Scandinavian valleys
and those of Scotland. It is the sea. I think I may safely say that the
valley glaciers of these countries during the great ice age _must_ have
reached the sea, and there have terminated their existence, just as the
Antarctic glaciers terminate at the present Antarctic ice-wall.
Public-domain text, read in full here on John Shaqi.
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