ИСТИНА

Surge-type glaciers are widespread in Spitsbergen. Nowadays, about 150 surgingglaciers are known here. They were established according to the evidences ofsudden terminus advance and special ice-surface features (loop moraines,unusually intense crevassing, etc.). Direct observations, historical records andmulti-temporal remote sensing data analysis are sources of these evidences whichare short-lived and allow to establish only those glacier surges that occurredrecently.Morphological features of deglaciated areas are the only evidence of surges notrecorded by sudden terminus advance and special ice-surface features. There aresome attempts to identify previously unknown surge-type glaciers using a specificsuite of indicator landforms (a land-system approach). These indicator landformsare thrust moraines, concertina eskers, subglacial crevasse-squeeze ridges,hummocky moraine and flutings.In this paper, an alternative approach is considered. It is based on the hypothesisthat the surging and non-surging behavior of the glaciers leads to the lateralmoraine formation of a different configuration outside the mountain valleys withidentical longitudinal profile of the lower part of the valley and at the exit from it.In order to test this hypothesis, the deglaciated area of 80 the most largest surge-type glaciers in West Spitsbergen were analyzed using open remote sensing dataof the npolar.no portal. Longitudinal profiles of the lower part of the valleys and atthe exit from it were evaluated using the ArcticDEM digital elevation model. Thereare direct and concave longitudinal profiles. Only 50% of glaciers have lateralmoraines outside the mountain valleys. 70% of them have direct longitudinalprofiles of the lower part of the valleys and at the exit from it. 86% of them havestraightforward lateral moraines which continue the sides of the valleys outsidethem unlike lateral moraines that diverge in different directions when leaving thevalley.Thus, if a non-surging glacier has a direct longitudinal profile of the lower part ofthe valleys and at the exit from it and straightforward lateral moraines outside thevalley, then with a high degree of probability we can speak of the surge behavior ofthe glacier during the formation of these lateral moraines. These morphologicalfeatures of lateral moraines can be used as evidences for identification ofpreviously unknown surge-type glaciers in Spitsbergen.The reported study was funded by MSU, Faculty of Geography (AAAA-A16-116032810055-0).https://sios-svalbard.org/sites/sios-svalbard.org/files/common/RSconference2020/BookOfAbstracts_SIOS_OnlineConference_June2020.pdf