Glacial history and geomorphology of Trygghamna, western Svalbard

Abstract

This study investigates Trygghamna, a small fjord on the western coast of Spitsbergen, Svalbard. In order to investigate its glacial history, high-resolution aerial images and swath bathymetry are used to produce a detailed geomorphological map of the area, with a focus on the Neoglacial extent of the three largest glaciers in the fjord, Protektor-, Harriet- and Kjerulfbreen. The landforms are classified into; subglacial, supraglacial, ice-marginal, glaciofluvial, proglacial landforms and extra-marginal surface cover. The ice-margins were reconstructed from ~1900, based on historical and geomorphological data together with aerial and satellite images. The Neoglacial maximum extent of the glaciers was reached around 1900, or the culmination of the Little Ice Age in Svalbard. Harriet- and Kjerulfbreen are considered to have exhibited surge behavior based on the presence of crevasse squeeze ridges (CSRs), which are considered unique for surging glaciers. The maximum extent is therefore, to some degree, related to a surge-event. Ice-marginal reconstructions and historical data suggest that the glaciers have been in overall retreat since then. It is more complex to determine if Protektorbreen surged as different factors in the glacier’s environment affect the formation and preservation potential of the landforms. The landform assemblages in the forefields do not show a good correspondence to previously published landsystem models for surge-type glaciers. Landsystem models should therefore be used with precaution when identifying undocumented surge-type glaciers. This investigation highlights the contrast in the record between terrestrial and marine environments of the glacier forefields in Trygghamna. Therefore it demonstrates the importance of incorporating evidence from both terrestrial and marine archives when reconstructing past glacial history, due to dynamic glacial behavior in different environments.