GEOMORPHIC EVIDENCE FOR INDEPENDENT ICECAPS ON NORTHWEST ICELAND

A combination of terrestrial geomorphic mapping, stratigraphic analyses, and Geographic Information Systems (GIS) analyses were used to investigate patterns of glacial erosion and the deglacial history of the southern and western Húnaflói coastal regions, northwest Iceland. The distribution of lakes on northwest Iceland is used to interpret the degree of ice scour on the landscape. Lake density, elevation, and distance from coast are analyzed using ArcGIS 9.0 software at 25km2 and 100km2 grid cell resolution. Lake density ranges from 0-56 % for the entire study area, with dense (>10%) concentrations on Gláma and Dranga upland plateaus on Vestfirdir and near Arnarvatnsheidi on the mainland.

Terrestrial geomorphic examination of the southern Húnaflói coastal region suggests that the region experienced a different style of glaciation than the western Húnaflói coastal region. Although these areas are adjacent geographically, there is geomorphic evidence that they were covered by independent ice caps. Evidence includes the distribution of ice-scour lakes, the presence or absence of alpine glacial features, and striation orientations. Western Húnaflói is dominated by landforms such as cirques, horns, and arêtes, which suggest an alpine style of glaciation over this region. In contrast, the southern Húnaflói area is dominated by rounded uplands covered by thin till, although some alpine features are present, especially near the Hvammstangi peninsula. Increased dating control is needed to determine the possible coalescence of the two ice caps in Húnaflói and to constrain the timing of deglaciation. A radiocarbon date on wood from the basal layer of a peat deposit suggests landscape stability in southern Húnaflói by at least 8.8 +/- 1.4 ka cal BP. This is a minimum age, and deglaciation probably occurred closer to 12 - 14 ka cal BP, which is suggested by marine core records.