Johnson, Joanne S.; Woodward, John; Nesbitt, Ian; Winter, Kate; Campbell, Seth; Nichols, Kier A.; Venturelli, Ryan A.; Braddock, Scott; Goehring, Brent M.; Hall, Brenda et al.
The Cryosphere (2025)Unambiguous identification of past episodes of ice sheet thinning below the modern surface and grounding line retreat inboard of present requires recovery and exposure dating of subglacial bedrock. Such efforts are needed to understand the significance and potential future reversibility of ongoing and projected change in Antarctica. Here we evaluate the suitability for subglacial bedrock drilling of sites in the Hudson Mountains, which are located in the Amundsen Sea sector of West Antarctica. We use an ice sheet model and field data – geological observations, glaciological observations and bedrock samples from nunataks, and ground-penetrating radar from subglacial ridges – to rate each site against four key criteria: (i) presence of ridges extending below the ice sheet, (ii) likelihood of increased exposure of those ridges if the grounding line was inboard of present, (iii) suitability of bedrock for drilling and geochemical analysis, and (iv) accessibility for aircraft and drilling operations. Our results demonstrate that although no site in the Hudson Mountains is perfect for this study when assessed against all criteria, the accessibility, N–S orientation and basaltic bedrock lithology of Winkie Nunatak's southernmost ridge (74.86° S, 99.77° W) make it a feasible site both for drilling and subsequent cosmogenic nuclide analysis. Furthermore, the ridge is strewn with glacial erratics at all elevations, providing valuable constraints on its early Holocene deglacial history. Based on our experiences during this study, we conclude with a series of recommendations for assessing site suitability for future bedrock drilling campaigns. We emphasise the importance of consulting a range of expertise prior to drilling and ensuring that sufficient field reconnaissance is undertaken (including obtaining detailed grids of radar survey data and bedrock samples).
We recommend certain ice core drilling sites in West Antarctica using a combination of glacier science and ice-penetrating radar. We do this because ice core science is essential to discovering the past history of those glaciers. Our recommendations take into account several factors: rocky ridges under the ice, how exposed those ridges were if the ice was higher in the past, bedrock quality, and whether science aircraft can land safely near the site. While no location was perfect across all criteria, we suggest the southern ridge of the Winkie Nunatak as a potential site based on several factors that make it a good site to analyze ice from.