Quantitative analyses of cirques on the Faroe Islands: evidence for time transgressive glacier occupation

• Published in: Boreas
• Main Authors: Wallick, Keyleigh N., Principato, Sarah M.
• Other Authors: American Philosophical Society
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2020
• Subjects: Faroe Islands
• Online Access: http://dx.doi.org/10.1111/bor.12458; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fbor.12458; https://onlinelibrary.wiley.com/doi/pdf/10.1111/bor.12458; https://onlinelibrary.wiley.com/doi/full-xml/10.1111/bor.12458

This study presents the first analysis of ice‐free cirques on the Faroe Islands using a Geographical Information System ( GIS ) and the Automated Cirque Metric Extraction ( ACME ) tool. The length, width, area, circularity, mean aspect, mean slope, and elevation range, minimum, and maximum were calculated using ACME . Cirque distance to coastline was measured using Arc GIS . A total of 116 cirques were identified. Mean cirque length is 950 m and mean cirque width is 890 m. Average cirque area is 0.8 km 2 and mean elevation is 386 m a.s.l. The modal orientation of the aspect of cirques is north‐northeast, with a vector mean of 7° and mean resultant length of 0.09. Aspect data have large dispersion, which shows evidence of cloudy ablation seasons in the past. The dispersion in aspect may also be related to the time transgressive nature of glacier occupation in these cirques. Past equilibrium‐line altitudes ( ELA s) of cirque glaciers reconstructed with the minimum point method resulted in a mean palaeo‐ ELA of 213 m a.s.l. Positive, linear relationships are observed between palaeo‐ ELA and cirque distance to coastline. There are at least two possible interpretations of this relationship: (i) that the cirque formation is dependent on pre‐existing topography with cirques forming at the head of valleys, which occurs at higher elevations further inland, and (ii) that this relationship demonstrates the importance of access to moisture for glacier survival. A combination of both interpretations is also possible. Positive linear relationships are also observed between longitude and palaeo‐ ELA indicative of palaeo‐precipitation patterns along an east–west gradient. Cirques on the Faroe Islands are smaller in length and width and present at lower elevations compared to cirques located in other regions of the world. The timing of glacial occupation in these cirques is not known, and the landforms likely formed over multiple glaciations.