Jökull - 01.12.1990, Page 33
Figure 1. The maximum extent of the inland ice sheet and its major ice-divides during the Búði advance
(Younger Dryas) and the Álftanes advance (Older Dryas) as first presented by the single advance deglaciation
(SAD) model and later by the double advance deglaciation (DAD) model. Legend: 1) 14C dates. 2) Main
'ce-divides. A) Margin of the ”Álftanes ice-sheet“. B) Margin of the ”Búði ice-sheet“ (Redrawn and modified
from Th. Einarsson and Albertsson, 1988). —Hámarksstœrð íslenska meginjökulsins og lega meginísaskila
hans á Búðaskeiði og Álftanesskeiði samkvæmt fyrri hugmyndum um tímasetningu og útbreiðslu þessara tveggja
fi'amrásarstiga. Tákn: 1) Geislakolsaldursákvarðanir. 2) Meginísaskil. A) Jaðar Alftanesjökuls. B) Jaðar
Búðajökuls (Th. Einarsson and Albertsson, 1988, breytt og endurteiknað).
the central highlands and Vestmannsvatn at the mouth
°f Reykjadalur in North Iceland (Fig. 1). This con-
hnuous inland ice sheet has been referred to as the
Búði ice-sheet“ (Th. Einarsson, 1967). Two 14C
dates of subfossil molluscs collected from marine sedi-
ntents at Hellisholtalækur and Brúará in South Iceland
have yielded ages of 9,435 ± 150 B.P. 2 (U-417)
and 9,565 ± 190 B.P. *) (T-362), respectively (Fig. 1)
(Th. Einarsson, 1964). Four 14C dates of marine mol-
luscs from sand sediments at Reykjavíkurflugvöllurin
Reykjavík, have yielded ages ranging between 10,085
± 160 B.P.1) (U-414)and 9,575 ± 260 B.P. ‘) (U-413)
(Fig. 1). Not considering the effect of apparent age
of living marine organisms, Th. Einarsson (1964)
concluded, that the shells at Hellisholtalækur dated
an early Preboreal retreat from the Búði moraine, and
that the moraine was formed during a Younger Dryas
advance of the ”Búði ice-sheet“, and that the shells
JÖKULL, No. 40,1990 31