Publications
5 results found
Reyes AV, Carlson AE, Clark J, et al., 2024, Timing of Cordilleran-Laurentide ice-sheet separation: Implications for sea-level rise, Quaternary Science Reviews, Vol: 328, ISSN: 0277-3791
During the last deglaciation, collapse of the saddle between the North American Cordilleran and Laurentide ice sheets led to rapid ice-sheet mass loss and separation, with meltwater discharge contributing to deglacial sea-level rise. We directly date ice-sheet separation at the end of the saddle collapse using 64 10Be exposure ages along an ∼1200-km transect of the ice-sheet suture zone. Collapse began in the south by 15.4 ± 0.4 ka and ended by 13.8 ± 0.1 ka at ∼56°N. Ice-sheet model simulations consistent with the 10Be ages find that the saddle collapse contributed 6.2–7.2 m to global mean sea-level rise from ∼15.5 ka to ∼14.0 ka, or approximately one third of global mean sea-level rise over this period. We determine 3.1–3.6 m of the saddle collapse meltwater was released during Meltwater Pulse 1A ∼14.6-14.3 ka, constituting 20–40% of this meltwater pulse's volume. Because the separation of the Cordilleran and Laurentide ice sheets occurred over 1–2 millennia, the associated release of meltwater during the saddle collapse supplied a smaller contribution to the magnitude of Meltwater Pulse 1A than has been recently proposed.
Nichols K, Rood D, Venturelli R, et al., 2023, Offshore-onshore record of Last Glacial Maximum-to-present grounding line retreat at Pine Island Glacier, Antarctica, Geology (Boulder), Vol: 51, Pages: 1033-1037, ISSN: 0091-7613
Pine Island Glacier, West Antarctica, is the largest Antarctic contributor to global sea-level rise and is vulnerable to rapid retreat, yet our knowledge of its deglacial history since theLast Glacial Maximum is based largely on marine sediments that record retreat to ~120 km downstream of the modern grounding line by the early Holocene. We show, with a suite of 10Be exposure ages from onshore glacial deposits directly adjacent to Pine Island Glacier, that this major glacier thinned rapidly in the early- to mid-Holocene. Our results indicate that Pine Island Glacier was at least 690 m thicker than present prior to ~8 ka. We infer that the rapid thinning detected at the site furthest downstream records the arrival and stabilization of the retreating grounding line at that site by 8-6 ka. By combining our exposure ages and the marine record, weextend knowledge of Pine Island Glacier retreat both spatially and temporally: to 50 km from the modern grounding line and to the mid-Holocene, providing a dataset that is important for future numerical ice sheet model validation.
Laurent V, Guillaume L, Genge M, 2023, Geological fieldwork in the time of COVID-19: Comparing the student learning experience during virtual and outdoor fieldwork
<jats:p>Fieldwork is a pedagogical cornerstone of many geoscience degrees. During the academic year 2020-21, the worldwide COVID-19 pandemic made outdoors fieldwork difficult, resulting in an urgent need to develop virtual alternatives. However, there is still more to learn about the impact of teaching fieldwork virtually on the student learning experience. This study aims to compare the student learning experience during virtual and outdoor fieldwork and establish the value of digital techniques to improve the inclusivity of geosciences degrees. Quantitative and qualitative data were collected to assess students&#8217; attitudes to both outdoor and virtual fieldwork in terms of accessibility, inclusivity and their learning experience. Our results show overall positive student responses to virtual fieldwork, with over half stating it adequately replicated the learning experience of outdoor fieldwork. Students also value outdoor fieldwork for the degree of autonomy it provides, and idea-sharing with peers; yet simultaneously the majority believed outdoor fieldwork is inherently exclusionary. This study concludes that virtual fieldwork, taught using interactive three-dimensional virtual outcrops set within virtual worlds, replicates the outdoor fieldwork learning experience as closely as possible. However, students missed some fundamental and important aspects of outdoor fieldwork, such as being outside in an immersive environment, or the social interactions with peers and staff that are specific to on-location fieldwork. This study recommends the use of virtual fieldtrips in addition to residential on-location fieldwork, as for a significant number of students virtual fieldwork may be a better way of accessing this valued pedagogy of the geosciences. Furthermore, virtual fieldwork has the potential to make geosciences more inclusive and attractive to a wider range of students.</jats:p>
Guillaume L, Laurent V, Genge MJ, 2023, Immersive and interactive three-dimensional virtual fieldwork: Assessing the student learning experience and value to improve inclusivity of geosciences degrees, Journal of Geoscience Education, Vol: 71, Pages: 462-475, ISSN: 1089-9995
Fieldwork is a pedagogical cornerstone of many geoscience degrees. During the academic years 2019–20 and 2020–21, the worldwide COVID-19 pandemic made outdoors fieldwork difficult, resulting in an urgent need to develop virtual alternatives. However, there is still more to learn about the impact of teaching fieldwork virtually on the student learning experience. This study aims to assess the student learning experience during immersive and interactive three-dimensional virtual fieldwork and establish the value of digital techniques to improve the inclusivity of geosciences degrees. Quantitative and qualitative data were collected to assess students’ attitudes to virtual fieldwork in comparison to outdoor fieldwork in terms of accessibility, inclusivity and their learning experience. Our results show overall positive student responses to virtual fieldwork, with over half stating it adequately replicated the learning experience of outdoor fieldwork. Students also value outdoor fieldwork for the degree of autonomy it provides, and idea-sharing with peers; yet simultaneously the majority believed outdoor fieldwork is inherently exclusionary. This study concludes that virtual fieldwork, taught using interactive 3D virtual outcrops set within virtual worlds, replicates the outdoor fieldwork learning experience as closely as possible. However, students missed some fundamental and important aspects of outdoor fieldwork, as being outside and the social interactions with peers and staff that are specific to on-location fieldwork. This study recommends the use of virtual fieldwork in addition to residential on-location fieldwork, as for a significant number of students virtual fieldwork may be a better way of accessing this valued pedagogy of the geosciences. Furthermore, virtual fieldwork has the potential to make geosciences more inclusive and attractive to a wider range of students.
Clark J, Carlson AE, Reyes A, et al., 2022, The age of the opening of the Ice-Free Corridor and implications for the peopling of the Americas, Proceedings of the National Academy of Sciences of the United States of America, Vol: 119, Pages: 1-6, ISSN: 0027-8424
The Clovis-first model for the peopling of the Americas by ∼13.4 ka has long invoked the Ice-Free Corridor (IFC) between the retreating margins of the Cordilleran and Laurentide ice sheets as the migration route from Alaska and the Yukon down to the Great Plains. Evidence from archaeology and ancient genomics, however, now suggests that pre-Clovis migrations occurred by at least ∼15.5 to 16.0 ka or earlier than most recent assessments of the age of IFC opening at ∼14 to 15 ka, lending support to the use of a Pacific coast migration route instead. Uncertainties in ages from the IFC used in these assessments, however, allow for an earlier IFC opening which would be consistent with the availability of the IFC as a migration route by ∼15.5 to 16.0 ka. Here, we use 64 cosmogenic (10Be) exposure ages to closely date the age of the full opening of the IFC at 13.8 ± 0.5 ka. Our results thus clearly establish that the IFC was not available for the first peopling of the Americas after the Last Glacial Maximum, whereas extensive geochronological data from the Pacific coast support its earlier availability as a coastal migration route.
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