Investigating methods for identifying paleo surge-type glaciers or highly dynamical ice flows in Trygghamn, west Spitsbergen

Sammanfattning: Surge-type glaciers exhibit a cyclic behaviour with an ice mass increase in the reservoir area during the inactive, quiescent phase and a rapid transportation of ice during the active, surge phase. In order to interpret the effects of climate change correctly it is important to distinguish between advances of surge-type glaciers and those of ‘normal’ glaciers, caused by climatic fluctuations. This is particularly important for the Arctic, which is predicted to experience the highest increase in temperature on the planet.                                  The dynamic and mechanism of surge-type glaciers can be used for understanding both modern and past ice sheet dynamic instabilities, threshold behavior and contribution to sea level rise. They are also suggested to be analogues for land-terminating paleo ice streams and surging ice sheet lobes, which makes them highly valuable as research objects. Though in order to understand their behavior, it is important to be able to identify them. In literature the number for surge-type glaciers on Svalbard varies between 13 and 90 %, thus it is important to work out methods, other than physical observations, for identification. Aerial photographs are a powerful tool for the identification and mapping of landforms and ice structures and for reconstructing glacier distribution. Though for mapping of ice facies and structures within the glaciers, which provide important information regarding the glaciers past dynamics, and is an important part of the identification, fieldwork is essential. Fieldwork is also much needed in order to interpret the landforms and their genesis correctly. It is suggested that the use of multiple methods for identifying surges, or highly dynamical ice flows, will improve the result and the reliability will increase.                                  In this thesis two different methods, structural glaciology and glacial geomorphology, have been used for interpreting the past behaviour of the four glaciers in Trygghamna, west Spitsbergen. Structural glaciology provides a way to determine the dynamic of surge-type glaciers for both the quiescent- and surge phase. By using glacial geomorphology it is possible to reconstruct former extent and thickness of small valley glaciers. The glaciers of Trygghamna exhibit evidence of a dynamic past, of which Harrietbreen and Kjerulfbreen bear enough evidence to be considered as surge-type glaciers. The lack of landforms on the forelands of Kiærbreen and Protektorbreen makes the interpretation difficult, though the ice facies and structures within the ice cave on Protektor-breen provide additional information and thus this glacier should at least be classified as a highly dynamical ice flow. Thus it is considered to not be suitable to only use one data type to determine whether a glacier is of surge-type or not. By use multiple methods the result will improve and the reliability will increase. The two methods used for this thesis are considered to be the least amount of methods needed in order to establish whether a glacier is of surge-type or not.