<scp>GIS</scp>analysis of cirques on<scp>V</scp>estfirðir, northwest<scp>I</scp>celand: implications for palaeoclimate

Abstract

This study presents the first regional analysis of cirques on V estfirðir, NW I celand, using a Geographical Information System ( GIS ). The length, width, elevation of cirque‐floor, latitude and the distance to the modern coastline (both ocean and fjord coastlines) of cirques were quantified using ArcGIS . The topographical analysis revealed a total of 100 cirques on western and northern V estfirðir. Several additional cirques are present, but they had poorly defined toewalls, making the cirque‐floor difficult to identify. Mean cirque length is 515 m and mean cirque width is 752 m. The modal orientation of the aspect of cirques is northeast, with a strong secondary mode to the northwest. Cirques at low elevations are more abundant close to the ocean, whereas cirques further from the ocean are present at high elevations. Three techniques were used to reconstruct past equilibrium‐line altitudes ( ELA s) of cirque glaciers: the cirque‐floor method, the altitude‐ratio method and the accumulation‐area ratio method. The largest range of past ELA s is generated from the cirque‐floor method with values from 40 up to 730 m. Mean past ELA values range from ∼395 to 423 m depending on the method used to reconstruct former ELA s. A strong positive relationship is observed between past ELA values and distance to the ocean demonstrating the importance of access to a moisture source for glacier survival. This relationship is stronger than the relationship between former ELA s and latitude. Based on the small size of cirque glaciers, it is likely that even minor fluctuations in the I rminger C urrent and the E ast G reenland C urrent influence cirque glaciation on V estfirðir.