Looking through drumlins: testing the application of ground-penetrating radar

first_imgGround-penetrating radar (GPR) is becoming a commonly applied technique ingeomorphology. However, its use in the study of subglacial bedforms has yet to be fully exploredand exploited. This paper presents the results of a GPR feasibility study conducted on a drumlinizedterrain in Cumbria, UK, where five drumlins were investigated using multiple radar antennafrequencies. The site was selected for the presence of nearby bedrock outcrops, suggesting a shallowdrumlinized diamict–bedrock contact and a permeable lithology. Despite the clayey sediment andunfavourable weather conditions, a considerable penetration depth of �12m was achieved when usinga 50MHz antenna, with a separation of 1 m, trace spacing of 1m and 128-fold vertical stack. Resultsindicate that the drumlinized diamict is in direct erosional contact with the bedrock. While the internaldrumlin geometry is generally chaotic on the stoss side, evidence of layering dipping downflow at anangle greater than the drumlin surface profile was found on the lee side. The inter-drumlin areascomprise �4m of infill sediment that masks part of the original drumlin profile. Overall, this studyindicates that GPR can be deployed successfully in the study of glacial bedform sedimentaryarchitecture.last_img

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