Jökull - 01.01.2010, Page 192

M. Da̧bski and P. Angiel
Table 3. Rates of glacier surface lowering since the exposure of the uppermost moraine ridge. For descripti-
on of sites, see Figure 5. – Afstæður hraði jökulhörfunar frá lokum Litlu ísaldarinnar metinn út frá ummáli
(vaxtarhraða) fléttna á jökulgörðunum.
max. age min. age
site E1 E2 SW E1 E2 SW
elev. above glacier (m) 96 85 98 96 85 98
age (AD) 1896 1900 1915 1930 1930 1930
years before AD 2008 112 108 93 78 78 78
glacier surface lowering rate (m/yr) 0.9 0.8 1.1 1.2 1.1 1.3
LIA
697
681
670
655
636
610
601
o
32
o
26
o
o
23
17
o
20
1896 - 1930
1938 - 1951
LIA
630
603
635
650
654
683
685
695
701
25
25
20
15
o
o
o
o
1915 - 1930
1938 - 1951
1996
1975
glacier glacier
LIA
635
25
o
1951
1975
slope inclination
altitude in meters a.s.l.
date and position of glacier surface
moraine ridge deposited during LIA maximum
beginning date of Salix arctica growth
SW slope E slope
Esjufjoll hut
..
Figure 7. A sequence
of lateral moraine
ridges on the slopes
of Skálabjörg along
profiles shown on
Figure 5. Dates of
former positions of
the glacier surface are
based on lichenome-
try (the LIA moraine
ridge), a topographic
map and the Jökull
40 photograph. –
Útbreiðsla fléttna á
jökulgörðum í hlíðum
Skálabjarga endur-
speglar hörfunarsögu
jökulsins.
taken in 1945 (Figure 4). A photograph taken by
Helgi Björnsson in 1994 (Jökull 56, p. 26) shows
this moraine being pushed northwards by the western
lope of Breiðamerkurjökull (Figure 1). These are the
first signs of deglaciation in Fossadalur. However,
the valley was still filled with glacier ice. Since
then the Fossadalur glacier front has retreated about
2 km producing a lake basin filled with melt water
and ice bergs (Figures 2D and 4). Water level in this
lake oscillates making clear-cut miniature strandflats
(Figure 2E).
An over 60 m deep lake basin at the southern end
of Skálabjörg (Figures 2F and 5) may have originated
as a deflation lake (Seppälä, 2004), which was later
significantly enlarged by melt-water action. The basin
was empty during our visit in mid-July 2008. Volcanic
rocks build the northern, southern and western slopes
of the main part of the basin and a very steep ice ed-
ge of Breiðamerkurjökull blocks water from the east
(Figure 5). Miniature strand-flats developed during
successive stages of water level lowering are clear-
ly visible on the slopes. The floor of the basin is
192 JÖKULL No. 60