A MORPHOMETRIC ANALYSIS OF CIRQUES ON EAST ICELAND USING GIS

This study represents the first quantitative analysis of cirques on the East Fjords region of Iceland. A combination of Google Earth and ArcGIS was used to measure cirque length, width, cirque-floor elevation, latitude and distance to both the open ocean and fjord coastlines. A total of 161 cirques on eastern Iceland were identified in Google Earth and quantitative analyses were completed in ArcGIS. The slope of the DEM of the study area was generated by creating a raster file based on the first derivative of the topography to determine headwall, toewall, and cirque-floor elevation. A minimum-point technique was developed to analyze 58 of the 161 cirques that had poorly defined toewalls. Mean cirque length is 706 m and mean cirque width is 715 m. The modal orientation of the aspect of cirques is north, with secondary modes to the northeast and northwest. The cirque-floor method, the altitude-ratio method, and the minimum-point technique were used to reconstruct paleo-equilibrium-line altitudes (ELAs) of paleo-cirque glaciers. Mean paleo-ELA values range from approximately 530 m to 665 m depending on the method used to reconstruct former ELAs. There is a strong positive relationship (r= 0.83, p<0.01) between paleo-ELA elevation and distance to the open ocean. This relationship supports the idea that access to a moisture source is crucial to glacier survival. No significant relationship is observed between past ELAs and latitude (r=0.01, p>0.05). Weather station data for the East Fjords region indicate that areas closer to the coastline receive higher levels of precipitation than inland locations. Fluctuations in the East Iceland Current (EIC) appear to have a large influence on cirque glaciation on east Iceland. The results of this study are similar to previous research conducted in the West Fjords region of Iceland as well as global studies of cirque characteristics. Paleo-ELAs in the West Fjords are also primarily influenced by distance to the coast; however the mean paleo-ELAs are lower in the West Fjords than in the East Fjords. Length, width, and altitudinal ratios of cirques vary globally, but the results of this study are consistent with global trends.