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Author for correspondence: Ole Bennike, E-mail: obe@geus.dk
Introduction
In 1978, Uffe Petersen of the former Geodetic Institute in Copenhagen sighted an islet north of Kaffeklubben Ø (Johnson, 2011). At that time, it was thought to be the most northern islet on Earth. The position of the islet was determined, and in 1979 it was visited by members of a Sirius sledge patrol and by a geological team. In 1980, it was observed for the last time; during the years following, it was searched for but not found. However, several other islets have been located in the region and it appears that the islets come and go. The islets have therefore been called “flygtige småøer” (literally ‘fleeting islets’) by Dawes (2003), “ghost islands” by Johnson (2011), “the Stray Dog Archipelago” by Shea (2012) and “islands on the move” by Dawes and Lautrup (2017). Dennis Schmitt noted that they behave like phantoms (Burress, 2004).
One may wonder if the islets are merely accumulations of sand, gravel and stones on floating sea ice. An ice floe covered by till or outwash gravel, with a small breeding colony of ivory gulls, was reported from North Greenland by Boertmann, Olsen and Gilg (2010). This ice floe was fairly thick and likely represented a tabular iceberg. Ice islands (tabular icebergs) in the Arctic Ocean may carry mineral-rich accumulations with living and even flowering plants (Hultén, 1962). The islets north of Peary Land appear to be real islands that are connected to the sea floor, and the area is probably too shallow for ice islands to enter.
At more southerly latitudes than Peary Land, islands commonly come and go. Waves and currents may, for example, form barrier islands that can disappear during storms and reappear during periods of calmer weather. The north coast of Peary Land is characterised by perennial sea ice and hence negligible wave activity. To the north of the zone with land-fast ice, drifting multiyear pack ice is found in the Arctic Ocean. In the summer, there is often an area of open water at the transition from land-fast ice to moving pack ice (Davies, 1972). Davies (1972, plate 2-NE) mapped the area around Kaffeklubben Ø as an area with up to 60% open water, with no icebergs or...