Jökull - 01.01.2012, Side 114

A. Schomacker et al.
Figure 1. A. Location of the study area in South Iceland. B. Terrain shaded relief model of the area around the
Mýrdalsjökull ice cap. Sólheimajökull is an outlet glacier of the southern part of the ice cap. – Staðsetning
Sólheimajökuls í suðurhluta Mýrdalsjökuls.
Pálsson, 2008) and were explained by glacier catch-
ment changes and ice-divide migrations (Dugmore,
1989; Dugmore and Sugden, 1991; Schomacker et
al., 2003; Casely and Dugmore, 2004; Kirkbride and
Dugmore, 2008). According to Thorarinsson (1943),
the glacier had major LIA advances around AD 1705,
1794 and 1820.
Although the ice marginal fluctuations of Sól-
heimajökull and other Icelandic glaciers in the 20th
and 21st century are generally well documented from
annual measurements and ground and aerial photogra-
phy, less is known about the changes in glacier thick-
ness and elevation. Glacier surface elevation changes
have been successfully quantified from time-series of
Digital Elevation Models (DEMs), e.g. on glaciers on
Svalbard (Nuth et al., 2007; Barrand et al., 2010),
Greenland (Motyka et al., 2010), and Alaska (Muskett
et al., 2008; Shugar et al., 2010). Recently, studies
of DEM-time series from Iceland have been applied
to study dead-ice melting and glacier retreat (Magn-
ússon et al., 2005; Schomacker and Kjær, 2007;
Schomacker, 2008; Jóhannesson et al., 2011; Aðal-
geirsdóttir et al., 2011). In the present study, time se-
ries of DEMs and aerial photographs from Sólheima-
jökull are used to decipher the changes in glacier sur-
face elevation and thickness between 1960 and 2010.
The aim of this paper is to explore the glacial geol-
ogy of Sólheimajökull using geomorphological map-
ping from aerial photographs, DEMs, and field work
as well as sedimentological logging of sections for
clarifying its late Holocene oscillations in time and
space. The chronology of Neoglacial glacial land-
forms is determined using 14C dating and cosmogenic
exposure dating of glacially striated bedrock and er-
ratic boulders. There are many challenges to cos-
mogenic exposure dating of glacial landforms in Ice-
land, mainly due to assumptions that have to be made
about erosion history and cosmogenic nuclide pro-
duction rates (Principato et al., 2006; Licciardi et al.,
2007, 2008). Samples of erratic boulders and bedrock
from Sólheimajökull were collected in order to ob-
tain absolute ages on glacial landforms and to assess
112 JÖKULL No. 62, 2012