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Abstract
Ice sheets greatly alter landscapes, particularly where ice flow is focused, creating deep fjords. Fjords serve as excellent examples of erosive processes occurring at the ice-bedrock interface. In contrast, there are cases where an ice sheet can leave behind little evidence of overriding and instead protect the landscape underneath. This work focuses on addressing a small portion of the classical problem of erosive versus non-erosive landscapes in Norway. I use 10Be inheritance as a key metric in identifying previous areas of non-erosive ice, which are potential patches of cold-based glaciation. I measured 10Be in 11 bedrock samples collected in two subregions in coastal Norway. Results show that despite the deglaciation of Ulriken during the Younger Dryas at ~11.5 ka, three apparent 10Be ages are ~17 ka at the summit (626 m asl). On the coastal mountain of Bremanger, my main research site, I have results from eight samples spanning from near sea level to 686 m asl. A deglaciation of ~15.5 ka is assigned to this section of the coast. From the collected samples, the two low-elevation samples are composed of heavily ice sculpted and polished bedrock and date to ~17 ka. Mid-elevation samples are somewhat glacially sculpted and date to ~40 ka. The highest-elevation samples have no evidence of glacial modification (only heavy surface weathering) and range from 65 to 110 ka. All samples are older than previously established deglaciation ages, indicating inherited 10Be from previous glacial-interglacial cycles throughout the Quaternary. Elucidating these patterns of erosive and non-erosive glacial processes in coastal Norway is essential to gain a better understanding of ice sheet processes and climate dynamics. Additionally, locating areas of cold-based ice cover could open the door for new lake-sediment records of pre-LGM sediments, such as those dating to the Last Interglacial.
