A QUANTITATIVE ANALYSIS OF CIRQUES ON TROLLASKAGI, NORTHERN ICELAND

The purpose of this study is to complete a quantitative analysis of cirques on Tröllaskagi, northern Iceland. Tröllaskagi is a volcanically inactive peninsula composed of Tertiary age basalt flows. At least 222 cirques were identified on Tröllaskagi using Google Earth. ArcGIS was used to measure length, width, aspect, latitude and distance to coastline of each cirque. A slope raster was constructed from the first derivative of the DEM of the study area. The headwall, cirque floor, and toewall of each cirque were determined using this raster. Paleo-equilibrium-line altitudes (ELAs) of paleo-cirque glaciers were calculated using the altitude-ratio method, the cirque floor method and a minimum point method. The minimum point method was used to analyze 36 cirques that did not have clearly defined toewalls. Average aspect was computed using an inverse tangent function based on lines constructed for the altitude-ratio method. Mean paleo-ELA values range from 717 m to 788 m depending on the method used to calculate paleo-ELA. Interpolation maps of ELA distributions suggest a positive relationship between paleo-ELA and distance to coastline and a negative relationship between paleo-ELA and latitude. The modal orientation of the cirques on Tröllaskagi is northeast. Preliminary results indicate an approximate mean cirque width of 662 m and an approximate mean cirque length of 701 m. Results of this study will be compared to cirque morphology and paleo-ELAs on both the East and West Fjords of Iceland. Additionally, paleo-ELA reconstructions will be compared with ELAs of modern cirque glaciers on Tröllaskagi.