the Expedition ARKTIS-XIX/4 of the research vessel POLARSTERN ...

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Store Koldewey
Store Koldewey is an elongated island off Northeast Greenland at 75°55’-76°45’ N
and 018°27’-019°10’ W (Fig. 6-1). The island is c. 80 km long and has a maximum
width of 10.5 km. Store Koldewey is separated from the mainland by the Dove Bugt
in the west and adjoins the Grønlandshavet in the east. Because of its location off
north eastern Greenland, it may have formed a natural barrier for the ice masses
coming down from the mainland in the past. Therefore, parts of the island may have
been unglaciated during the LGM or, relatively early deglaciated during the period of
ice retreat.
Located in the East Greenland Caledonian fold belt most parts of Store Koldewey are
composed of Precambrian methamorphic bedrocks (mainly gneisses) older than
1800 Ma. Additionally, fossil (e.g., bivalves and ammonites) bearing Jurassic and
Cretaceous marine sediments are exposed at the eastern shoreline. Quaternary
glacial deposits are widespread on Store Koldewey. Particularly, on the
southernmost tip of the island the bedrock is completely concealed by Quaternary
sediments.
The morphology on Store Koldewey is dominated by a flat-toped mountain range with
an elevation up to 900 m a.s.l. (Fig. 6-1). The west coast is characterized by steep
slopes close to the shoreline, whereas the eastern coast is dominated by extended
plains with a maximum elevation of 150 m a.s.l. The mountain range is repeatedly
interrupted by several U-shaped and west to east oriented valleys, which are partially
filled up by freshwater reservoirs of various depths. The lakes are exclusively fed by
melt water. Many smaller lakes and ponds exist on the eastern plain in morphological
depressions.
The climate in the north eastern part of Greenland is characterized by low
precipitation (c. 150 mm/a) and low temperatures between -24°C and 4°C (Born &
Böcher 2001). The vegetation cover on Store Koldewey is only sparse and
dominated by Salix arctica, Dryas octopetala, Cassiope tetragona, Eriophorum, and
different lichens and mosses. The local fauna is represented by various birds and a
few mammals, e.g., arctic fox, arctic hare, lemmings and polar bears.
Geographical Society Ø
Geographical Society Ø is located off East Greenland at 72°40’-73°04’ N and
021°52’-24°35’ W (Fig. 6-1). The island is bordered by the Sofia Sund and the Foster
Bugt in the north, the Vega Sund in the south, and the Cambridge Bugt in the east.
Studies in the past have revealed that major parts of the island were glaciated during
the LGM and that the ice retreat in the Vega Sund occurred after c. 11-10 ka BP
(Wagner et al. 2000). Findings of pre-Holocene shell materials on the north eastern
part of the island (Funder & Hjort 1973, Hjort 1981) suggest that this part was not or
not heavily glaciated during the LGM. However, glacial reworking and redeposition
cannot be excluded.
The western part of Geographical Society Ø is composed of Upper Paleozoic
sediments while the eastern part is built up by Mesozoic sediments. Tertiary volcanic