Jökull - 01.12.1999, Page 64

Figure 2. End moraines of Höfðabrekkujökull from
the 1890"s. —Jökulgarðar við Höfðabrekkujökul frá
lokum 19. aldar. Remundargilshöfuð er við vinstri
jaðar myndarinnar.
It is possible that the end moraine ranges south of
the Rjúpnafell hill mark the eastern continuation of
these moraines as they lie at a similar distance from
the glacier snout.
The remainders of two additional moraine ranges
are located by Selfjall, about 4.5 km south of the
glacier snout and just east of the Sandvatn river
(moraines I on map). These moraines are up to 5 m
high and record a later phase of the glacier’s advance.
The next distinct range of end moraines lies inter-
mittently along the whole length of the glacier fore-
field, about 450 m from the southern snout, 1400 m
from the central snout, and 1100 m from the north-
ern snout of the glacier (moraines II on map). These
moraines mark the maximum glacier extent during the
“Little Ice Age” (1600-1920), with the broad lobed
glacier advance culminating during the 1890-1900 's
(Björnsson, 1979; Heim, 1983; Kriiger, 1994). They
form low, 2-3 m high, hummocks with surfaces com-
monly made up of erratic boulders (Figure 2). The
largest of these erratics, located in the central part of
this range, has a height of about 5 m and a maximum
circumference of 30.8 m (Figure 3). At this location,
the uppermost 0.5 m of the moraine is made up of
morainic diamict with a sandy-stony, slightly loamy
texture. At 0.5-1.6 m depth, the moraine is made up
of black tephra with boulders, 20-25 cm in diameter.
Figure 3. Erratics in the end moraine zone from the
1890's. — Stœrsta bjargið íjökulgörðunumfrá lokum
19. aldar. Bjargið er 5 m hátt og 30,8 m að ummáli.
Another (inner) moraine range, consisting of a
650 m long and 4-5 m high ridge, lies within the cen-
tral part of the marginal zone, about 300 m closer to
the glacier snout (moraines II on map). Both ranges
(II) lie within several dozen meters of each other in the
southern and northern part of the marginal zone and
both have been dissected by meltwaters. The inner
moraine range constitutes of two series. A lower unit
of grey-coloured, sandy-gravelly diamict with clear
traces of glaciotectonic disturbances and an upper unit
of glacial till, probably from a later episode of Höfða-
brekkujökull’s advance.
Closer to the glacier, four additional end moraine
hummocks can be distinguished (moraines III on
map). These moraines formed during the last fifty
years and are best preserved in the central part of the
marginal zone (Figures 4 and 5).
A moraine ridge with an ice-cored character, is
presently being formed at the glacier snout, almost
along its whole length. It already has the shape of
a fully formed ridge in some places while in oth-
ers it is still in direct contact with the glacier snout.
This moraine is made up of sediments represent-
ing different facies of direct ice contact, such as
different types of diamict generated by mud-flows,
rubbly-stony scree build-up, and differential sluicing,
mostly by melt waters. Along some sections of the
snout, the glacier is advancing over a moss-grown
62 JÖKULL, No. 47