| Autor: |
Barth, Aaron M., Ceperley, Elizabeth G., Vavrus, Claire, Marcott, Shaun A., Shakun, Jeremy D., Caffee, Marc W. |
| Předmět: |
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| Zdroj: |
Geochronology; 6/13/2022, p1-18, 18p |
| Abstrakt: |
Alpine glaciers in the western United States are often associated with late-Holocene Little Ice Age (LIA) advances. Yet, recent studies have shown many of these glacial landforms are remnants of latest-Pleistocene retreat with only the most cirque-proximal moraines preserving LIA activity. Additionally, the timing and magnitude of glacial advances during the Neoglacial-LIA interval remains uncertain with presumed maximum extents occurring during the LIA driven by lower Northern Hemisphere insolation levels. Here we present Be surface exposure ages from a glacial valley in the Beartooth Mountains of Montana and Wyoming, United States. These new data constrain the presence of the glacier within 2-3 km of the cirque headwalls by the end of the Pleistocene with implications for large-scale retreat after the Last Glacial Maximum. Cirque moraines from two glaciers within the valley preserve a late-Holocene readvance with one reaching its maximum prior to 2.1 ± 0.2 ka and the other 0.2 ± 0.1 ka. Age variability among the moraines demonstrates that not all glaciers were largest during the LIA and presents the possibility of regional climate dynamics controlling glacial mass balance. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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