Deglaciation dynamics following the Little Ice Age on Svalbard:

Søren H. Rasmussen
terrestrial Svalbard poly<strong>the</strong>rmal glacier.
Larsbreen and Platåbreen are different than
<strong>the</strong> typical Svalbard model, which is
caused by <strong>the</strong> presence of a debris cover.
The debris-cover reduces <strong>the</strong> melt rate and
<strong>the</strong>reby active glacier ice coring <strong>the</strong>
moraines all <strong>the</strong> way to <strong>the</strong> front of <strong>the</strong>
moraine. This allows <strong>the</strong> glacier still to be
at <strong>the</strong> LIA maximum. Retreat of <strong>the</strong> glacier
is manifested by thinning of <strong>the</strong> glacier
instead. By melting debris accumulating on
<strong>the</strong> glacier surface and <strong>the</strong>reby <strong>the</strong> front of
<strong>the</strong> clean glacier ice moves upglacier.
Glaciofluvial processes are transporting
sediments away form <strong>the</strong> moraines.
Nearest <strong>the</strong>se meltwater channels wasting
of <strong>the</strong> moraines are larges, do to <strong>the</strong>
channels cut down into <strong>the</strong> moraine,
removing of sediments and contributory
factor for generating debris-flow. The
steep sides of <strong>the</strong> valley Larsbreen is lying
in and thinning of <strong>the</strong> glacier are causes for
a sloping of <strong>the</strong> moraine toward <strong>the</strong>
middle. The slope of <strong>the</strong> moraine means
<strong>the</strong> gravity flow and transport with water
are working in <strong>the</strong> same direction. At
Platåbreen some areas of <strong>the</strong> moraine are
nearly horizontal and <strong>the</strong>reby preventing
gravity flow. Fur<strong>the</strong>r more <strong>the</strong>re are now
channels observed in <strong>the</strong>se areas, telling
that only a small amount of water are
running here.
By thinking <strong>the</strong> deglaciation to <strong>the</strong> end
it is estimated that debris on <strong>the</strong> flat laying
frontal moraine of Platåbreen has a high
preservation potential, because <strong>the</strong> less
running water and gravity flow. In contrast
moraine lying on steep valley sides, like
<strong>the</strong> moraine of Larsbreen, has a low
potential of preservation due to gravity and
water working toge<strong>the</strong>r, transporting <strong>the</strong>
sediments to streams for fur<strong>the</strong>r transport
out of <strong>the</strong> system.
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