Controversy continues over the geological history of the Dry Valleys. The “Stabilist ” school argues the Dry Valleys
Summary Debate continues whether Antarctica has been in a stable deep freeze since the Miocene or experienced major fluctuations in climate and glacier extent though the Pliocene. A key question here is whether ashes are in situ and postdate their underlying deposits. There are at least three reason...
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| Format: | Text |
| Language: | English |
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| Online Access: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.534.978 http://geoinfo.nmt.edu/staff/dunbar/publications/documents/slettin_mann_mcintosh_dunbar_2007_isaes.pdf |
| Summary: | Summary Debate continues whether Antarctica has been in a stable deep freeze since the Miocene or experienced major fluctuations in climate and glacier extent though the Pliocene. A key question here is whether ashes are in situ and postdate their underlying deposits. There are at least three reasons suggesting that some of these ashes are reworked. First, we found blocks of glacially-transported ash in Beacon Valley. After disintegrating, these erratics leave localized deposits of relatively pure volcanic ash that is much older than the surfaces they overlie. Second, most surface-age estimates older than 2 Ma in the Dry Valleys are based on the eruption (Ar-Ar) ages of these reputed in situ tephras. In contrast, the majority of cosmogenic exposure ages are younger. Third, geomorphic and weathering processes are active today in Dry Valleys, indicating a younger landscape than Miocene age implied by the ancient |
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