GLACIAL EROSION PATTERNS AND MORAINE SEQUENCES ON THE NORTHWEST PENINSULA OF ICELAND

Terrestrial geomorphic mapping of part of the Northwest Peninsula of Iceland is in progress to address questions regarding ice extent and glacial history during the late Quaternary. Distinct erosive glacial landforms including, cirques, arêtes, horns, and u-shaped valleys dominate the northwest and southeast sections of the study area. These features vary in elevation from approximately 500 to 780m. The presence of striations and grooves indicates that this area was glaciated by warm based ice. A Geographic Information System (GIS) is used to map bedrock-silled lake density, which is interpreted as a proxy for ice scour over the landscape. A 10km by 10km grid, super-imposed over the hydrography coverage, shows that lake density varies from zero percent up to 8.8% of the land area. Lake density is the highest in the regions of former ice centers over Glama and on the upland from Steingrimsfjardarheidi to Ofeigsfjardarheidi. Additional calculations using the GIS software, such as the relationship of lake density to the topography and distance to the coast, are in progress. Chlorine-36 cosmogenic isotope exposure dating is used to determine the ages of some of these erosive glacial landforms, and results are pending.

Evidence for Holocene glacial activity is concentrated in valleys currently occupied by outlet glaciers of the Drangajokull Icecap. Sequences of moraines in Kaldalon, Leirufjordur, and Reykjafjordur are mapped and show at least five episodes of glacial advance. A radiocarbon date of 3328+/- 45 14C years on wood at the base of a peat section on top of the second outermost moraine in Kaldalon provides a minimum age for Neoglacial activity in this valley. Lichenometry measurements of Rhizocarpon gr. geographicum on poorly vegetated moraines in Kaldalon correlate with the Little Ice Age. Cosmogenic exposure ages on the boulders from the outermost moraines in Kaldalon and Leirufjordur are pending.