Jökull - 01.01.2012, Page 164

S. Brynjólfsson et al.
Figure 9. Evolution of the geomorphology after a surge of a small cirque glacier. Based on studies at Búrfells-
jökull which surged 2001–2004 and Teigarjökull which surged in 1971. Phase A, in the end of a surge, debris
is pronounced in the steep and crevassed glacier margin and the terminal moraine is still shapeless. Phase B,
about five years after the surge, the margin has flattened and debris covers the stagnant ice in the marginal area.
The glacier has retreated from the terminal moraine which is still ice-cored. Phase C, about forty years after
the surge, the glacier margin has flattened out, dead-ice, hummocky moraine and other landforms are found in
front of the glacier. – Myndin sýnir þróun landmótunarumhverfis skálar/hvilftar framhlaupsjökla á Tröllaskaga,
byggt á athugunum við Búrfellsjökul og Teigarjökul. A) Við lok framhlaups, B) um fimm árum eftir framhlaup
og C) um 40 árum eftir framhlaup.
In phase C, the stagnant glacier snout continues
to melt. Extensive hummocky moraine is formed as
thickness of sediment increases on the ice surface and
dead-ice melting becomes insignificant. Finally, after
a few decades when the dead-ice has largely melted,
supraglacial and englacial sediment are predominant
on the proglacial surface.
Landsystems model for surge-type cirque glaciers
in alpine environments of Iceland
Investigations of the geomorphology of the surge-type
glaciers, Búrfellsjökull and Teigarjökull, are the ba-
sis of the new landsystem model (Figure 10). The
landsystem model is divided into two main parts; the
distal zone and the proximal zone.
Distal zone: Small end moraines define the extent of
a certain surge. The end moraines are either push or
dump moraines, or a combination of both. The sed-
iment is rich in coarse grained and angular material,
whereas the total of fine grain sizes (clay, silt) is lim-
ited. Hummocky moraine often links to the proximal
slope of the end moraines. In some cases, the subdued
end moraines constitute more a step-like sheet in the
landscape, rather than a distinct, single-crested end
moraine. Dead-ice buried in the end moraines and in
the drift to their proximal sides can take tens of years
to melt. Therefore, evidence of dead-ice melting, such
as extension cracks, backslumping, and sinkholes oc-
cur in association with the end moraines.
162 JÖKULL No. 62, 2012