Jökull - 01.01.2016, Blaðsíða 62

Paweł Molewski and Leon Andrzejewski
Figure 9. Deposits of the kame terrace. A: Dead glacial ice in the bottom of profile A. B: Cobble in silt deposits
at a depth of about 3 m in profile A. C: Rippled, cross-laminated sands in profile B. D: Low-angle cross-strat-
ification sands in profile B. – Setlög í sethjöllunum á 7. og 8. mynd. A) Dauðís í botni sniðs A. B) Fallsteinn í
siltlögum í sniði A. C) Gáróttur og skáhallandi sandur í sniði B. D) Vægt skáhallandi sandlög í sniði B.
4.9 to 9.2 cm/s. The deposition of the unit’s sedi-
ments was probably influenced by hyperpycnal flows
(Boogs, 1995). The cyclic sets of varying scales which
were recognised in the sediment are evidence of short-
and long-term changes in the material supply and sed-
imentation conditions in the water body, associated
with the ice ablation rate. The silty deposits were ac-
cumulated in a period of little ablation in low tem-
peratures and a lack of rainfall. The silty-sandy de-
posits were accumulated in a period of increased abla-
tion and relatively high temperature and rainfall con-
ditions. The changeability of ablation rate followed
a daily, annual or seasonal cycle. The low lithofacial
variation of the analysed sediment proves stable depo-
sition conditions. The silt fraction advantage indicates
the dominance of accumulation from suspension. The
presence of single cobbles of diameters ranging from
10 to 15 cm in the sediments may be interpreted as
the result of iceberg melting (dropstones), is shown by
the deformed lamination below the cobble and draped
lamination on top of the clast.
Lithofacies A2 is 2.6 m thick and comprises a ho-
mogeneous sequence of horizontally stratified sand,
sandy-silt and silty-sand (Sh, SFh, FSh) (Figure 8A).
62 JÖKULL No. 66, 2016