Jökull - 01.11.1998, Blaðsíða 20

THE STUDY AREA
Eiríksjökull (1672 m) is the largest table mountain
in Iceland (Piper, 1973). The mountain is crudely rect-
angular in plan, extending 11 km from east to west and
9 km from north to south, and it is capped by a small
ice cap (Figure 1). The geology of the area around
Eiríksjökull has been mapped and described in some
detail (Pjeturss, 1904; Thoroddsen, 1911; Pálsson,
1945; Ólafsson and Pálsson, 1978; Atkins, 1972;
Piper, 1973; Downie, 1972) but the absolute age of the
Eiríksjökull table mountain is not known although it
has been inferred to date back to the last glaciation
(Atkins, 1972; Piper, 1973; Downie, 1972). The moun-
tain is made of ca. 750 m of thin sub-aerial lava flows
overlying hyaloclastite rocks at least 320 m in thick-
ness, a total of at least 1070 m thick volcanic succes-
sion. Stratification and structures in the lowermost
units of the hyaloclastites are indicative of subaqueous
pyroclastic flows suggesting subglacial depositional
environment. Cross bedding, graded bedding, slump,
flame structure and climbing ripples were recognised
in exposures in and around the Flosagil ravine on the
westem side of the mountain (Figure 1). The upper-
most units of the hyaloclastite succession show very
fine grained deposits in contrast to the lower more
coarser units. A petrographical difference occurs in
the lava shield covering the hyaloclastites succession.
Fig. 1. Key map of the Eiríksjökull ice cap showing the study site. B denotes the Borgarfjörður area.
- Yfirlitskort af Eiríksjökli.
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JOKULL, No. 46, 1998