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Geochronology

Physical Geography Division

Department of Geography

University of Zurich - Irchel

Winterthurerstr. 190 

CH-8057 Zurich, Switzerland

 

tel.: +41-44-635 51 21

fax.: +41-44-635 68 41

        Surface Exposure Dating Laboratory

 

    Prof. Markus Egli                                                                       Tel. +44 (0)44 635 5146
    Dr. Dagmar Brandova                                                                Fax +44 (0)44 635 6841

Cosmogenic nuclides are created through the collision of cosmic rays with atomic nuclei. These nuclei can be atmospheric (e.g. nitrogen, oxygen) or terrestrial. Rock surface dating (surface exposure dating) relies on terrestrially formed nuclides and soil dating relies on atmospherically formed nuclides.

Surface exposure dating with cosmogenic nuclides

Cosmic rays impinge on an exposed rock surface and induce nuclear reactions with the nucleus of the minerals and create “cosmogenic isotopes”, one of them being 10Be. The concentration of these isotopes is measured by accelerator mass spectrometry (AMS) and gives a direct measure of the exposure time of the rock surface.

Since the method’s introduction it has been applied to study more and more specific questions in earth sciences and within different geomorphic contexts. The method has contributed to a significant improvement in the chronology of late-würmian and Holocene glacier fluctuations.

Soil dating with cosmogenic nuclides

Meteoric Beryllium is formed in the atmosphere and infiltrates into soils by precipitation where it is adsorbed by the upper  permeable layers of soil.