Holocene Sea-Ice Variations and Paleoenvironmental Change, Northernmost Ellesmere Island, N.W.T., Canada

Abstract

More than 70 samples of Holocene driftwood between present sea level and the marine limit are plotted on an emergence curve from Clements Markham Inlet (82° 40'N). Three periods of driftwood abundance and sparsity are recognized. These are interpreted as indications of climatically induced changes in summer sea ice conditions. Period 1 extends from initial driftwood entry ca. 8900 BP until ca. 4200 BP. During this period driftwood penetration increases with greatest abundance (= reduced summer sea ice) ca. 6000 to 4200 BP. During Period 2 (ca. 4200 to 500 BP) driftwood penetration is sparse whereas in Period 3 (<500 BP) driftwood bordering the present shoreline exceeds all the samples in the previous periods. Driftwood dates from elsewhere in the Canadian and Greenland High Arctic show similar periods.

In Clements Markham Inlet the initiation of abundant driftwood penetration corresponds with the deposition in marine sediments of fossil bryophytes (25 species) dated 6400 BP. This increased plant productivity is also interpreted as indicating summer warmth/higher precipitation associated with the greater open water. Accompanying these bryophytes is the disjunct marine pelecypod Limatula (Lima) subauriculata which presently has a subarctic-boreal distribution. This paleoenvironmental information is discussed in relation to Holocene ice core records and the history of Arctic Ocean sea ice stability.