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Paper No. 237-3
Presentation Time: 8:40 AM
DEFINING THE GEOMORPHOLOGY OF CLIFF-TOP DUNES: CASE STUDY OF THE CHIPPEWA RIVER VALLEY, WI, USA
Aeolian dunes located upon an escarpment are found in a variety of geographic settings worldwide. They are often described as having parabolic morphologies and exist downwind of a topographic barrier to flow. Despite an extensive body of research on parabolic dunes, a relative paucity of research has focused on a comprehensive understanding of the distribution, variable genesis, and broader paleoenvironmental significance of dunes found in this landscape assemblage. References to these dunes are scattered across >100 years of literature, where a wide array of terms are used despite often referring to the same landform (e.g. cliff dunes, cliff-top dunes, bluff-top dunes, perched dunes, valley marginal dunes, perched dunes). A variety of formation models have also been suggested. Given the lack of synthesis in understanding this landform, we recommend these globally ubiquitous aeolian deposits be referred to as cliff-top dunes (CTD) and define them as aeolian landforms in a cliff-top position, commonly parabolic in morphology, and produced by a combination of geomorphic processes interacting with a topographically-altered wind regime. Based on prior literature, we further characterize CTD into two geomorphic settings: coastal and terrestrial. Within these geomorphic settings, CTD can be classified into coastal normal, hybrid coastal, terrestrial normal, and terrestrial fluvial. To test the applicability of this classification of CTDs, we investigate newly discovered CTDs in the Chippewa River valley, WI, USA. We utilize LiDAR-derived topographic data and aerial imagery to map their distribution and characterize their morphology throughout the valley. In addition, GPR and OSL dating at focused sites are used to determine the structure and age of deposition of these landforms. Our results suggest these CTDs are terrestrial fluvial CTDs and deposition coincides with the post-glacial incisional history of the lower Chippewa River.