Cosmogenic 10 Be and 26 Al ages of Holocene moraines in southern Norway I: testing the method and confirmation of the date of the Erdalen Event ( c . 10 ka) at its type-site

• Published in: The Holocene
• Main Authors: Matthews, John A., Shakesby, Richard A., Schnabel, Christoph, Freeman, Stewart
• Format: Article in Journal/Newspaper
• Language: English
• Published: SAGE Publications 2008
• Subjects: Paleontology; Earth-Surface Processes; Ecology; Archeology; Global and Planetary Change; Norway; glacier
• Online Access: http://dx.doi.org/10.1177/0959683608096585; http://journals.sagepub.com/doi/pdf/10.1177/0959683608096585

Abstract: Cosmogenic nuclide dating ( 10 Be and 26 Al) is applied to boulders on two moraine ridges at the type-site of the early-Holocene Erdalen Event, southern Norway, dated previously using radiocarbon. Quartz-rich rock samples yielded 10 Be age estimates between 9.8 ± 1.2 and 10.1 ± 1.1 ka (external uncertainties, ± 1σ), with an average of 9.95 ka. These age estimates are statistically indistinguishable from the independent radiocarbon age estimate. 26 Al age estimates, which ranged from 9.4 ± 1.1 to 11.2 ± 1.3 ka and averaged 10.1 ka, provided useful corroboration of the 10 Be results. Although current levels of precision and accuracy are insufficient to distinguish between the ages of younger inner and older outer moraines, the results demonstrate the potential of the method at suitable sites where radiocarbon dating is not possible. Several environmental factors, including effective glacial erosion, stability of moraine slopes, snow cover of sufficiently shallow depth and short duration, and the absence of colluvial contamination, appear to have been instrumental in the success of applying the method at this site. The results confirm the timing and extent of the Erdalen Event in southern Norway with implications for Holocene glacier chronology and millennial-scale climatic variability.