Jökull - 01.01.2020, Blaðsíða 20

Glacier extent in Iceland, 1890–2019
Figure 6: The extent of Langjökull ice cap, Eiríksjökull, Þórisjökull, Ok glacier and Hrútfellsjökull at several times since
the LIA maximum in ∼1890. – Útlínur Langjökuls, Eiríksjökuls, Þórisjökuls, Oks og Hrútfellsjökuls á mismunandi tímum
frá því um 1890.
references therein). This outlet glacier reached its
Holocene maximum extent approximately 2000 years
ago, whereas the LIA maximum moraines are located
some tens of metres outside the 1904 margin, which is
depicted on the map of the Danish General Staff from
1907 (Danish Geodetic Institute, 1941b). The fore-
field of the eastern margin of Mýrdalsjökull (Sand-
fellsjökull and Öldufellsjökull) has been mapped by
Evans et al. (2018), providing a high-resolution delin-
eation of the glacier margin at the LIA maximum, and
the forefield of Kötlujökull was mapped by Kjær and
Krüger (2001). Thoroddsen (1906) noted that Kötlu-
jökull was in an advanced state in 1893, and no termi-
nal moraines have been found farther from the glacier.
The outermost moraines of Sléttjökull were formed
around the turn of the 20th century, supported by a
photograph taken by Karl Sapper in 1906 (Krüger et
al., 2010). Jökulhlaups due to subglacial eruptions or
released from subglacial geothermal areas may have
washed away or buried moraines in the forefield. Ter-
minus variations of Mýrdalsjökull may have been af-
fected by volcanic eruptions of Katla (Larsen, 2010)
that may melt several km3 of ice and change the sub-
glacial topography of the Mýrdalsjökull ice cap.
Mýrdalsjökull and Eyjafjallajökull may have been
connected during the maximum LIA stage (H. Björns-
son, 1993) but it is uncertain whether the Fimmvörðu-
háls ridge (Figure 7), between the two ice caps, was
covered by dynamically moving glacier ice or thick
firn (Sigurðsson, 2004). The LIA extent of Eyjafjalla-
JÖKULL No. 70, 2020 17