MORPHOMETRIC ANALYSIS OF ICE SCOUR LAKES IN NORTHERN ICELAND: A PROXY FOR ICE SHEET DYNAMICS

The purpose of this study is to conduct a GIS analysis of ice scour lakes in Iceland to evaluate lake morphology as a potential proxy for paleo-ice flow direction and velocity. The primary goal of the study is to examine morphological properties of ice scour lakes in regions that experienced different rates of ice flow during the Last Glacial Maximum (LGM), as interpreted from streamlined subglacial landforms. A total of 3,850 ice scour lakes in three areas in Northwest (the Westfjords), Northern (Húnaflói) and Northeast (Vopnafjorður) Iceland were measured and analyzed. Hydrologic data from the National Land Survey of Iceland served as the basis for all GIS analyses. Topographic data from the ArcticDEM were used in GIS analyses. Lake parameters including density, packing, elevation, and distance to coastline were quantified in ArcGIS. An automated GIS plug-in created by Guler et al. (2021), PolyMorph-2D, was used to quantify lake orientation, area and elongation. Significance of non-directional results was analyzed with the Kruskal-Wallis H-Test and directional results were interpreted using Rayleigh’s Z-Test. The density of ice scour lakes was significantly higher in the Westfjords than in the other two study areas, ranging from 1-124 lakes per 5km² with a mean of 31 lakes per 5km² (H=40.247, df=2, p<.050). The elongation ratio (length-to-width ratio) was also significantly higher in the Westfjords than in the other two study areas, ranging from 1.001-7.352 with a mean of 2.010 (H=21.815, df=2, p<.050). In all three study areas there was a weak but non-zero preferred orientation of the long axes of lakes, calculated as r-values, a measure of angular dispersion (Húnaflói r=0.228; Westfjords r=0.262; Vopnafjorður r=0.283). The orientation results of this study align with the flow directions of proposed LGM ice streams in Northern and Northeast Iceland. The high intensity of erosion across the Westfjords study area, interpreted from high density of lakes, may suggest unique ice sheet dynamics relative to the other two study areas and presence of an independent ice sheet covering the Northwest peninsula of Iceland. Differential intensity of glacial erosion interpreted from regions of high and low lake density in Vopnafjorður provides support for a proposed ice divide in Northeast Iceland.