Abstract
Ambiguous landscape histories can arise from equivocal or incomplete geomorphological, sedimentological or geochronological evidence. In this study, we apply quantitative analyses to robustly assess the origin and age of a field of rounded mounds, known as ‘The Hillocks’. Using clast analysis, the sediment is shown to be consistent with a landslide origin but inconsistent with other glacial sediments in the region. Cosmogenic 10Be exposure age dating suggests The Hillocks formed ~8 ka. Ground‐penetrating radar reveals that the deposit rests upon deltaic foreset beds; combined with topographical data, we calculate a deposit volume of ~15–27 M m3, consistent with the estimated volume of the proposed source area. Overall, our data support a rock avalanche origin, indicating that by 8 ka the valley was ice‐free at The Hillocks’ location, and the level of Lake Wakatipu was lower than 340 m asl by this time. The Dart River delta shoreline was situated somewhere between The Hillocks and the present day shoreline at that time, and has prograded at a maximum average rate of 1 m a−1 since ~8 ka. These findings are significant given the lack of landforms by which to constrain glacial or post‐glacial landscape histories in this region of New Zealand.
Original language | English |
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Pages (from-to) | 685-696 |
Number of pages | 12 |
Journal | Journal of Quaternary Science |
Volume | 34 |
Issue number | 8 |
Early online date | 29 Nov 2019 |
DOIs | |
Publication status | Published - Nov 2019 |
Keywords
- kame
- Lake Wakatipu
- landform origin
- paraglacial
- rock avalanche
ASJC Scopus subject areas
- Arts and Humanities (miscellaneous)
- Palaeontology
- Earth and Planetary Sciences (miscellaneous)