Editing Loess (section)

==History of research==
The term "Löß" was first described in [[Central Europe]] by [[Karl Cäsar von Leonhard]] (1823–1824),<ref>Leonhard K. C. von (1823–1824). ''Charakteristik der Felsarten''. 3 Vols., J. Engelmann Verlag Heidelberg, pp. 772.</ref> who had reported yellowish brown, silty deposits along the Rhine valley near [[Heidelberg]].<ref name="Frechen 2011"/> [[Charles Lyell]] (1834) brought the term into widespread usage, observing similarities between "loess" and its derivatives along the loess bluffs in the Rhine and in [[Mississippi River|Mississippi]].<ref name="Frechen 2011" /> At the time, it was thought that the yellowish brown silt-rich sediment was of [[fluvial]] origin and had been deposited by large rivers.<ref name="Frechen 2011" /> The [[Aeolian processes|aeolian]] origin of the loesses was recognized later (Virlet D'Aoust 1857),<ref>Virlet D'Aoust P.T. (1857). "''Observations sur un terrain d`origine météorique ou de transport aerien qui existe au Mexique et sur le phénomène des trombes de poussière auquel il doit principalement son origine''". ''[[Geol. Soc. France, Full.]]'', 2d, Ser. 2, 129–139.</ref> particularly due to the convincing observations of loesses in [[China]] by [[Ferdinand von Richthofen]] (1878).<ref name="Frechen 2011"/><ref>Richthofen F. von (1878). "''Bemerkungen zur Lößbildung''". ''[[Verh Geol Reichsanst]]'', Berlin, pp 1–13.</ref> A tremendous number of papers have been published since then, focusing on the formation of loesses and on loess/[[paleosol]] (older soil buried under deposits) sequences as the archives of climate and environment change.<ref name="Frechen 2011"/> These water conservation works have been carried out extensively in China, and the research of loesses in China has been ongoing since 1954. [33]

[[File:A Loess Storm on the Pampas of Argentina.jpg|thumb|left|Illustration of a [[Pleistocene]] loess storm in the [[Pampas]] by [[Charles R. Knight]]]] 
Much effort was put into setting up regional and local loess [[stratigraphy|stratigraphies]] and their correlations (Kukla 1970, 1975, 1977).<ref>Kukla G. (1970). "Correlation between loesses and deep-sea sediments". ''[[Geologiske Foreningen Foerhandlingar]]'' '''92''': 148–180. Stockholm.</ref><ref>Kukla G. J. (1975). "Loess stratigraphy of Central Europe". In: Butzer K. W. & Isaac G. L. (eds.) After the Australopithecus, pp. 99–188. Mouton, The Hague.</ref><ref>{{cite journal |last1=Kukla |first1=G. J. |year=1977 |title=Pleistocene Land-Sea Correlations I. Europe |journal=[[Earth-Science Reviews]] |volume=13 |issue=4 |pages=307–374 |doi=10.1016/0012-8252(77)90125-8|bibcode=1977ESRv...13..307K }}</ref> However, even the chronostratigraphical position of the last interglacial soil correlating with marine [[isotope]] substage 5e was a matter of debate, due to the lack of robust and reliable numerical dating, as summarized, for example, by Zöller et al. (1994)<ref>{{cite journal |last1=Zöller |first1=L. |last2=Oches |first2=E. A. |last3=McCoy |first3=W. D. |year=1994 |title=Towards a revised chronostratigraphy of loess in Austria with respect to key sections in the Czech Republic and in Hungary |journal=[[Quaternary Geochronology]] |volume=13 |issue=5–7|pages=465–472 |doi=10.1016/0277-3791(94)90059-0|bibcode=1994QSRv...13..465Z }}</ref> and Frechen et al. (1997)<ref>{{cite journal |last1=Frechen |first1=M. |last2=Horváth |first2=E. |last3=Gábris |first3=G. |year=1997 |title=Geochronology of Middle and Upper Pleistocene loess sections in Hungary |journal=[[Quaternary Research]] |volume=48 |issue=3 |pages=291–312 |doi=10.1006/qres.1997.1929|bibcode=1997QuRes..48..291F |s2cid=128551599 }}</ref> for the Austrian and Hungarian loess stratigraphy, respectively.<ref name="Frechen 2011"/>

Since the 1980s, [[thermoluminescence]] (TL), [[optically stimulated luminescence]] (OSL), and infrared stimulated luminescence (IRSL) dating have been available, providing the possibility for dating the time of loess (dust) depositions, i.e., the time elapsed since the last exposure of the mineral grains to daylight.<ref name="Frechen 2011" /> During the past decade, [[luminescence dating]] has significantly improved by new methodological improvements, especially the development of single [[wikt:aliquot|aliquot]] regenerative (SAR) protocols (Murray & Wintle 2000)<ref>{{cite journal |last1=Murray |first1=A. S. |last2=Wintle |first2=A. G. |year=2000 |title=Luminescence dating of quartz using an improved single aliquot regenerative-dose protocol |journal=[[Radiation Measurements (journal)|Radiation Measurements]] |volume=32 |issue=1 |pages=57–73 |doi=10.1016/S1350-4487(99)00253-X|bibcode=2000RadM...32...57M }}</ref> resulting in reliable ages (or age estimates) with an accuracy of up to 5 and 10% for the [[last glacial]] record.<ref name="Frechen 2011"/> More recently, luminescence dating has also become a robust dating technique for penultimate and antepenultimate glacial loess (e.g. Thiel et al. 2011,<ref>{{cite journal |last1=Thiel |first1=C. |last2=Buylaert |first2=J. P. |last3=Murray |first3=A. S. |last4=Terhorst |first4=B. |last5=Tsukamoto |first5=S. |last6=Frechen |first6=M. |last7=Sprafke |first7=T. |year=2011 |title=Investigating the chronostratigraphy of prominent palaeosols in Lower Austria using post-IR IRSL dating |journal= E&G Quaternary Science Journal|volume=60 |issue=1|pages=137–152 |doi=10.3285/eg.60.1.10|doi-access=free |hdl=11858/00-1735-0000-0001-B8C7-1 |hdl-access=free }}</ref> Schmidt et al. 2011)<ref>{{cite journal |last1=Schmidt |first1=E. D. |last2=Semmel |first2=A. |last3=Frechen |first3=M. |year=2011 |title=Luminescence dating of the loess/palaeosol sequence at the gravel quarry Gaul/Weilbach, Southern Hesse (Germany) |journal= E&G Quaternary Science Journal|volume=60 |issue=1|pages=116–125 |doi=10.3285/eg.60.1.08|doi-access=free |hdl=11858/00-1735-0000-0001-B8C4-7 |hdl-access=free }}</ref> 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).<ref name="Frechen 2011"/><ref>{{cite journal|last1=Frechen|first1=M.|title=Loess in Eurasia|journal=Quaternary International|date=2011 |volume=234|issue=1–2|pages=1–3|doi=10.1016/j.quaint.2010.11.014|bibcode=2011QuInt.234....1F}}</ref> Furthermore, the numerical dating provides the basis for quantitative loess research applying more sophisticated methods to determine and understand high-resolution proxy data including the palaeodust content of the atmosphere, variations of the atmospheric circulation patterns and wind systems, palaeoprecipitation, and palaeotemperature.<ref name="Frechen 2011" />

Besides luminescence dating methods, the use of radiocarbon dating in loess has increased during the past decades. Advances in methods of analyses, instrumentation, and refinements to the radiocarbon calibration curve have made it possible to obtain reliable ages from loess deposits for the last 40–45 ka. However, the use of this method relies on finding suitable in situ organic material in deposits such as charcoal, seeds, earthworm granules, or snail shells.<ref name=":0" /><ref>{{Cite journal|last1=Újvári|first1=Gábor|last2=Stevens|first2=Thomas|last3=Molnár|first3=Mihály|last4=Demény|first4=Attila|last5=Lambert|first5=Fabrice|last6=Varga|first6=György|last7=Jull|first7=A. J. Timothy|last8=Páll-Gergely|first8=Barna|last9=Buylaert|first9=Jan-Pieter|last10=Kovács|first10=János|date=2017-12-12|title=Coupled European and Greenland last glacial dust activity driven by North Atlantic climate|journal=Proceedings of the National Academy of Sciences|volume=114|issue=50|pages=E10632–E10638|doi=10.1073/pnas.1712651114|issn=0027-8424|pmc=5740632|pmid=29180406|bibcode=2017PNAS..11410632U|doi-access=free}}</ref><ref>{{Cite journal|last1=Moine|first1=Olivier|last2=Antoine|first2=Pierre|last3=Hatté|first3=Christine|last4=Landais|first4=Amaëlle|last5=Mathieu|first5=Jérôme|last6=Prud’homme|first6=Charlotte|last7=Rousseau|first7=Denis-Didier|date=2017-06-13|title=The impact of Last Glacial climate variability in west-European loess revealed by radiocarbon dating of fossil earthworm granules|journal=Proceedings of the National Academy of Sciences|volume=114|issue=24|pages=6209–6214|doi=10.1073/pnas.1614751114|issn=0027-8424|pmc=5474771|pmid=28559353|bibcode=2017PNAS..114.6209M|doi-access=free}}</ref>