Formation of crevasse-squeeze ridges at Trygghamna, Svalbard

• Published in: Earth Surface Processes and Landforms
• Main Authors: Ben-Yehoshua, Daniel, Aradóttir, Nína, Farnsworth, Wesley R., Benediktsson, Ívar Örn, Ingólfsson, Ólafur
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2023
• Subjects: crevasse fill ridges; crevasse-squeeze ridges; glacier retreat; landform formation; ridge networks; subglacial processes; surging glacier; Svalbard; Trygghamna; glacier
• Online Access: https://curis.ku.dk/portal/da/publications/formation-of-crevassesqueeze-ridges-at-trygghamna-svalbard(9450a912-c5cf-4808-b6f5-14219ebdb881).html; https://doi.org/10.1002/esp.5631; https://curis.ku.dk/ws/files/357188025/Earth_Surf_Processes_Landf_2023_Ben_Yehoshua_Formation_of_crevasse_squeeze_ridges_at_Trygghamna_Svalbard.pdf

Crevasse-squeeze ridges (CSRs) are landforms that have been unequivocally linked to surge-type glaciers. The formation of CSRs has been discussed since they were first defined in the mid-1980s. Here, we describe geometric CSR networks from the terrestrial glacier forefields of two glaciers in Trygghamna, Western Svalbard. No glacier surges have been observed in Trygghamna; however, the presence of the CSRs signifies past surge activity. Detailed geomorphological maps were constructed, and the spatial context of these landforms described. Cross-sections of several CSRs highlight ridge architecture, structure and relationships to surrounding landforms and sediments. Most CSRs are symmetrical in cross-profile, orientated perpendicular or oblique to the ice-flow direction. Like previous investigations, we observe these ridge networks on top of till and flutes. Additionally, we, for the first time, document CSRs deposited directly on non-glaciogenic subsurfaces, namely, beach gravels and bedrock. Our findings confirm previous CSR formation theories; basal sediments are squeezed into bottom-up crevasses during surges, which are subsequently transported englacially until surge termination and are finally released by melt out from stagnant ice. Consequently, a network of CSRs is the product of a significant reorganisation and down-glacier transport of basal sediment, exemplifying how single surges are agents of glacial sediment redistribution. These formation processes are illustrated in a refined schematic model. The results further contemporary understanding of CSRs in terrestrial surge-type glacier settings and may also apply to landforms and sediments in certain marine settings and palaeoglacial environments.