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| Titel |
Glacier activity at the Lateglacial / Holocene transition inferred from the Swiss Alps |
| VerfasserIn |
Inga Schindelwig, Naki Akçar, Sven Lukas, Peter W. Kubik, Christian Schlüchter |
| Konferenz |
EGU General Assembly 2010
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 12 (2010) |
| Datensatznummer |
250043628
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| Zusammenfassung |
| High-alpine environments react sensitively to changes in climate. Depending on size,
catchment area and valley topography, mountain glaciers response relatively fast with
advances and recessions to shifts in temperature and precipitation (e.g. Oerlemans, 2005).
About half of the present glaciers in the Swiss Alps are located in the highest mean altitudes
areas. Past glacier activity beyond actual glacier extent is sometimes easily identified, such as
the moraines related to the Little Ice Age. Records of older glacier activity, however, are
usually less abundant. Lateglacial glacier advances are often documented by moraine
complexes.
By comparing geomorphological characteristics within and between several investigated
sites across the Swiss Alps, a relative chronology of glacier oscillations and re-advances was
established. A cross-correlation of moraines in the same high-alpine climatic region allows to
conclude that moraine ridges in comparable relative positions with similar morphologies and
characterized by similar equilibrium line altitude depressions (Gross et al. 1977; Maisch,
1987), may be allocated to the same supra-regional trends in climate change. Surface
exposure dating on well defined moraines gives the absolute chronology for the
relative framework. More than 50 samples from erratic boulders on the crestline of
moraines and glacially abraded bedrock were dated using the radionuclide 10Be.
According to the results on boulders of the outer moraines, the oldest ridge coincides in
time with the initial phase of the Younger Dryas (e.g. Gerzensee Oscillation). In
addition, a number of Lateglacial and early Holocene advances have been identified
(Preboreal Oscillation, Younger Dryas and Gerzensee Oscillation). 10Be exposure ages
on moraines of the innermost Lateglacial complexes, but distinctly downvalley
from Little Ice Age moraines point to cold conditions in the Alps during the early
Holocene.
REFERENCES
Gross, G., Kerschner, H. & Patzelt, G. (1977): Methodische Untersuchungen über die
Schneegrenze in alpinen Gletschergebieten. Zeitschrift für Gletscherkunde und
Glazialgeologie, 12, 223-251.
Maisch, M. (1987): Zur Gletschergeschichte des alpinen Spätglazials: Analyse und
Interpretation von Schneegrenzdaten. Geographica Helvetica, 42, 63-71.
Oerlemans, J. (2005): Extracting a Climate Signal from 169 Glacier Records. Science,
308, 675-677. |
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