Loess - History of Research

History of Research

The term “Löß” was first described in Central Europe by Karl Cäsar von Leonhard (1823-1824) who reported yellowish brown, silty deposits along the Rhine valley near Heidelberg. Charles Lyell (1834) brought this term into widespread usage by observing similarities between loess and loess derivatives along the loess bluffs in the Rhine and Mississippi. At that time it was thought that the yellowish brown silt-rich sediment was of fluvial origin being deposited by the large rivers. It took until the end of the 19th century until the aeolian origin of loess was recognized (Virlet D'Aoust 1857), especially the convincing observations of loess in China by Ferdinand von Richthofen's (1878). A tremendous number of papers have been published since then, focusing on the formation of loess and on loess/palaeosol sequences as archives of climate and environment change.

Much effort was put into the setting up of regional and local loess stratigraphies and their correlation (Kukla 1970, 1975, 1977). But even the chronostratigraphical position of the last interglacial soil correlating to marine isotope substage 5e has been a matter of debate, owing to the lack of robust and reliable numerical dating, as summarized for example in Zöller et al. (1994) and Frechen, Horváth & Gábris (1997) for the Austrian and Hungarian loess stratigraphy, respectively.

Since the 1980s, thermoluminescence (TL), optically stimulated luminescence (OSL) and infrared stimulated luminescence (IRSL) dating are available providing the possibility for dating the time of loess (dust) deposition, i.e. the time elapsed since the last exposure of the mineral grains to daylight. During the past decade luminescence dating has significantly improved by new methodological improvements, especially the development of single aliquot regenerative (SAR) protocols (Murray & Wintle 2000) resulting in reliable ages (or age estimates) with an accuracy of up to 5 and 10% for the last glacial record. More recently luminescence dating has also become a robust dating technique for penultimate and antepenultimate glacial loess (e.g. Thiel et al. 2011, Schmidt et al. 2011) allowing for a reliable correlation of loess/palaeosol sequences for at least the last two interglacial/glacial cycles throughout Europe and the Northern Hemisphere (Frechen 2011). Furthermore, the numerical dating provides the basis for quantitative loess research applying more sophisticated methods to determine and understand high-resolution proxy data, such as the palaeodust content of the atmosphere, variations of the atmospheric circulation patterns and wind systems, palaeoprecipitation and palaeotemperature.