Jökull - 01.12.1990, Blaðsíða 70

Table I. Climatic parameters for some meteorolog-
ical stations in North Iceland (Einarsson 1976). —
Veðurfarsþœttir á nokkrum veðurstöðvum nyrðra.
Station Mean temperature ° C Mean precipit. in mm
1931-1960 1931-1960“
January July year year
Siglunes -0,6 9,0 3,7 629
Akureyri -1,5 10,9 3,9 474
Grímsey -0,5 8,1 3,1 678
Vaglir -3,0 10,1 2,6 658
Sandur -2,3 10,0 3,1 486
Húsavík — 1,2 10,2 3,9 531
aDays with precipitation >0.1mm were 139 at Akureyri and 137
at Húsavík. Mean number of days with frost during 1951-1960 was
151 for Akureyri.
mires (Hallgrímsson, 1976). Sparsely vegetated allu-
vial fans and talus slopes are abundant. This remote
valley was still inhabited in the fifties, by farmers
keeping sheep, horses and a few milk-cows (Sigurðs-
son, 1954). The vegetation of the valley is still utilized
by neighbouring counties for sheeps’ summer-grazing.
The climate is rather cool. Winters are harsh with
heavy snow cover and long duration. Summers can
be relatively warm, with some days having temper-
atures above 20 °C, but they are short, an estimate
gives about 90 days with mean temperature above
7,5 °C (cf. Ragnarsson, 1977). According to the
isotherm maps given in Einarsson (1976) for January
and July 1931-1960, at Krosshólsmýri, Flateyjardalur,
the mean temperature is on the one hand between —2
and zero °C and on the other hand from 8 to 10 °C.
The mean annual precipitation for this normal period
is between 600 and 800 mm (Sigfúsdóttir in Einars-
son 1976, p. 97, Fig. 40). Climatic parameters for
the nearest meteorological stations are given in Table
I (for location see Fig. 1).
Flateyjardalur is situated in one of the areas
Steindórsson (1937; 1962) assumes to be a refugium,
where plants survived the last glaciation. Geomorpho-
logical studies (Thorarinsson, 1937; Einarsson, 1959;
Norðdahl, 1979; 1983; 1991) indicate abundance of
nunataks at the maximum extent of the Weichselian
Figure 2. A simplified geological map of Flateyjar-
dalur and location of the sediment core investigated
by means of pollen analysis (black dot). Shaded area;
till; black areas are moraine ridges. (Modified from
Norðdahl 1979). —Jarðfræðikort af Flateyjardal.
Borstaðurinn í Krosshólsmýri er merktur með svört-
um punkti, skyggð svœði sýna jökulruðning og svört
jökulgarða.
glaciation. Also considerable land areas, today below
sea level, were ice-free as the sea level was lower than
today in times of glacier advances duringthe Late We-
ichselian Substage (Einarsson, 1961; 1963, Norðdahl,
1979).
The deglaciation history of the area has been de-
scribed by Norðdahl (1979; 1983; 1990). Accord-
ing to him Flateyjardalur became ice-free during the
Late Weichselian Substage as the ice-dammed lakes
in Fnjóskadalur had an outlet north across Flateyjar-
dalsheiði and through Flateyjardalur to the sea in the
bay of Skjálfandi.
68 JÖKULL,No. 40, 1990