This section draws on two book chaper publications by Bethan Davies. Authors accepted versions can be viewed below, along with the link to the published chapters. Not all dating methods are covered here; please refer to the published book chapters for more information.
Archival, incremental and relative dating techniques
Davies, B.J., 2022. 4.12: Dating Glacial Landforms I: Archival, Incremental, Relative Dating Techniques and Age-Equivalent Stratigraphic Markers, in: Haritashya, U., Harbor, J., French, H.M. (Eds.), Treatise on Geomorphology (Second Edition): Cryospheric Geomorphology. Elsevier, pp. 225-248. (link)
Abstract
Combining glacial geomorphology and understanding the glacial process with geochronological tools is a powerful method for understanding past ice-mass response to climate change. These data are critical if we are to comprehend ice mass response to external drivers of change and better predict future change.
The first book chapter (I) covers key concepts relating to the dating of glacial landforms, including absolute and relative dating techniques, direct and indirect dating, precision and accuracy, minimum and maximum ages, and quality assurance protocols. The chapter then covers the dating of glacial landforms using archival methods (documents, paintings, topographic maps, aerial photographs, satellite images), relative stratigraphies (morphostratigraphy, Schmidt hammer dating, amino acid racemization), incremental methods that mark the passage of time (lichenometry, dendroglaciology, varve records), and age-equivalent stratigraphic markers (tephrochronology, palaeomagnetism, biostratigraphy).
When used together with radiometric techniques, these methods allow glacier response to climate change to be characterized across the Quaternary, with resolutions from annual to thousands of years, and timespans applicable over the last few years, decades, centuries, millennia and millions of years. All dating strategies must take place within a geomorphological and sedimentological framework that seeks to comprehend glacier processes, depositional pathways and post-depositional processes, and dating techniques must be used with knowledge of their key assumptions, best-practice guidelines and limitations.
Radiometric techniques
The second book chapter (II) covers numerical ages.
Davies, B.J., 2022. Dating Glacial Landforms II: Radiometric Techniques, in: Haritashya, U. (Ed.), Treatise in Geomorphology (Second edition). Cryospheric Geomorphology. Elsevier, pp. 249-280. (link)
Abstract
Numerical ages for glacial landforms are required to position palaeo ice extent at a given point in space and time. Radiometric methods, when appropriately calibrated and measured, allow intra- and inter-regional correlation and the production of large empirical datasets across varied and fragmented Quaternary deposits. This chapter focuses on radiocarbon ages for terrestrial and marine environments, cosmogenic nuclide dating (including exposure ages of bedrock and glacially transported boulders, and burial dating for glacial sediments), optically stimulated luminescence dating of glaciofluvial outwash, and Argon/Argon or Potassium/Argon dating of moraines interbedded with volcanic sequences.
For each method, the key principles and concepts are outlined, sampling methodologies are discussed, calibration techniques and protocols are provided, and quality assurance protocols are suggested. All dating stratigraphies should take place within a geomorphological and sedimentological framework, and dating techniques must be used with knowledge of their key assumptions, best-practice guidelines and limitations.
Combining glacial geomorphology with carefully constructed numerical age chronologies allows the timing of significant stabilisations of outlet glaciers at moraines to be characterised, whilst vertical transects down mountain ranges provide information on past rates and magnitudes of ice-mass thinning. These typically more expensive methods may be used with great effect in conjunction with archival, relative and incremental dating techniques, and with age-equivalent stratigraphic markers. This greatly increases the spatial coverage of the numerical dating methods and allows regional stratigraphies to be constructed. These data are critical if we are to understand ice mass response to the internal and external, climatic drivers of change.
