View source for Loess

{{short description|Sediment of accumulated wind-blown dust}}
{{about|the geologic material|the statistical technique|local regression}}
[[File:LoessVicksburg.jpg|thumb|Loess in [[Vicksburg, Mississippi]], United States]]

'''Loess''' ({{IPAc-en|US|'|l|ɛ|s|,_|'|l|ʌ|s|,_|ˈ|l|oʊ|.|ə|s}}, {{IPAc-en|UK|ˈ|l|oʊ|.|ə|s|,_|'|l|ɜ|s}}; from {{langx|de|Löss}} {{IPA|de|lœs|}}) is a [[clastic rock|clastic]], predominantly [[silt]]-sized [[sediment]] that is formed by the accumulation of wind-blown [[dust]].<ref name="Frechen 2011"/> Ten percent of Earth's land area is covered by loesses or similar [[deposition (geology)|deposits]].<ref name=" VasiljevicEtAl2011">{{cite journal |url=https://ojs.zrc-sazu.si/ags/article/viewFile/1328/1091 |title=Loess Towards (Geo) Tourism – Proposed Application on Loess in Vojvodina Region (North Serbia) |first1=D. A.|last1=Vasiljevic |first2=S. B.|last2=Markovic |first3=T. A.|last3=Hose |first4=I.|last4=Smalley |first5=K.|last5=O'Hara-Dhand |first6=B.|last6=Basarin |first7=T.|last7=Lukic |first8=M. D.|last8=Vujicic |journal=Acta Geographica Slovenica |year=2011 |volume=51 |issue=2 |pages=390–406 |doi=10.3986/AGS51305 |doi-access=free |bibcode=2011AcGSG..51..391A |language=sl}}</ref>

Loess is a [[periglacial]] or [[aeolian processes|aeolian]] (windborne) sediment, defined as an accumulation of 20% or less of [[clay]] with a balance of roughly equal parts [[sand]] and silt (with a typical [[grain size]] from 20 to 50 micrometers),<ref>{{cite book |last1=Smalley|first1=I. J. |last2=Derbyshire|first2=E. |year=1990 |chapter=The definition of 'ice-sheet' and 'mountain' loess |title=Area 22 |pages=300–01}}</ref><ref>{{cite book |vauthors=Donahue, Miller, Shickluna |year=1977 |title=Soils: An Introduction to Soils and Plant Growth |edition=4th |publisher=[[Prentice Hall]]}}</ref> often loosely cemented by [[calcium carbonate]]. Usually, they are [[homogeneity and heterogeneity|homogeneous]] and highly [[Porosity#Porosity in earth sciences and construction|porous]] and have vertical capillaries that permit the sediment to fracture and form vertical [[cliff|bluffs]].

==Properties==
[[File:Loess landscape china.jpg|thumb|Loess near [[Hunyuan]], [[Datong]], [[Shanxi]], China]]
[[File:Löss 1.jpg|thumb|Loess from the [[Rhine]] lowlands near [[Mannheim]] with calcareous concretions]]
Loesses are [[wikt:homogeneous|homogeneous]], [[Porosity#Porosity in earth sciences and construction|porous]], [[friable]], pale yellow or [[buff (color)|buff]], slightly [[wikt:coherent|coherent]], typically non-[[stratum|stratified]], and often [[calcareous]]. Loess grains are [[Rounding (sediment)|angular]], with little polishing or rounding, and composed of [[quartz]], [[feldspar]], [[mica]], or other [[mineral]] crystals. Loesses have been described as rich, dust-like soil.<ref>Pearson Prentice Hall - World Studies - Europe and Russia</ref>

Loess deposits may become very thick: at more than a hundred meters in areas of Northwestern China and tens of meters in parts of the [[Midwestern United States|Midwestern]] United States. Loesses generally occur as blanket deposits that cover hundreds of square kilometers. The deposits are often tens of meters thick. Loesses often have steep or vertical faces.<ref>Neuendorf, K.E.K., J.P. Mehl Jr., and J.A. Jackson, 2005, ''Glossary of Geology.'' [[Springer-Verlag]], [[New York City]], 779 pp., {{ISBN|3-540-27951-2}}</ref> Because the grains are angular, loesses will often stand in banks for many years without [[Slump (geology)|slump]]ing. This type of soil has "vertical cleavage", and thus, it can be easily excavated to form cave dwellings, which is a popular method of making [[yaodong|human habitations]] in some parts of China. However, loesses can readily erode.

In several areas of the world, loess [[ridge]]s have formed that had been aligned with the [[prevailing wind]]s during the last [[glacial maximum]]; these are called "[[paha (landform)|paha]] ridges" in America and "greda ridges" in Europe. The formation of these loess [[dune]]s has been explained as a combination of wind and [[tundra]] conditions.

==Etymology==
The word ''loess'', with connotations of origin by wind-deposited accumulation, was introduced into English from the [[German language|German]] {{Lang|de|Löss}} (1824),<ref>[https://inhigeo.org/wp-content/uploads/2024/12/207-koelbl-ebert_m._karl_von_leonard_defines_the_term_loess_200_years_ago.pdf KARL CAESAR VON LEONHARD INTRODUCED THE TERM "LOESS"]. INHIGEO, 2024.</ref> which can be traced back to [[Alemannic German|Swiss German]] and is [[cognate]] with the English word ''loose'' and the German word {{Lang|de|los}}.<ref>{{cite web|url=http://www.etymonline.com/index.php?term=loess|title=loess |publisher=Online Etymology Dictionary}}</ref> It was first applied to the [[Rhine]] River valley loesses around 1821.<ref>{{cite encyclopedia|url=https://www.britannica.com/EBchecked/topic/346022/loess |title=loess (sedimentary deposit) |encyclopedia=Encyclopædia Britannica |access-date=2013-12-22}}</ref><ref>{{cite web|url=http://www.dwds.de/?qu=L%C3%B6ss&submit_button=Suche&view=1 |title=DWDS &#124; Suchergebnisse |publisher=Dwds.de |access-date=2013-12-22}}</ref>

==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"/> Research on loesses in China to support [[water conservation]] has been ongoing since 1954.{{fact|date=October 2025}}

[[File:A Loess Storm on the Pampas of Argentina.jpg|thumb|left|[[Artist's impression]] of a scene during the Pleistocene Era. A [[dust storm]] in the distance represents a typical cause of present-day loess. (1918 painting 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>

==Formation==
[[File:Luvos Heilerde.jpg|thumb|[[Medicinal clay]] produced by [[Luvos]]. The clay is composed of loess with a fineness grade of 1.]]
According to Pye (1995),<ref>{{cite journal | last1 = Pye | first1 = K | year = 1995 | title = The nature, origin and accumulation of loess | journal = [[Quaternary Science Reviews]] | volume = 14 | issue = 7–8| pages = 653–667 | doi=10.1016/0277-3791(95)00047-x| bibcode = 1995QSRv...14..653P}}</ref> four fundamental requirements are necessary for the formation of loess: a dust source, adequate wind energy to transport the dust, a suitable accumulation area, and a sufficient amount of time.<ref name="Frechen 2011"/>

===Periglacial loess===
[[Periglacial]] (glacial) loess is derived from the floodplains of [[glacier|glacial]] [[braided river]]s that carried large volumes of glacial meltwater and sediments from the annual melting of continental ice sheets and mountain ice caps during the spring and summer. During the autumn and winter, when the melting of the ice sheets and ice caps ceased, the flow of meltwater down these rivers either ceased or was greatly reduced. As a consequence, large parts of the formerly submerged and unvegetated floodplains of these braided rivers dried out and were exposed to the wind. Because the floodplains consist of sediment containing a high content of glacially ground flour-like [[silt]] and [[clay]], they were highly susceptible to winnowing of their silts and [[clay]]s by the wind. Once entrained by the wind, particles were then deposited downwind. The loess deposits found along both sides of the [[Mississippi embayment|Mississippi River alluvial valley]] are a classic example of periglacial loess.<ref name="MuhsOthers2003a">{{cite journal|last1=Bettis|first1=E.A.|last2=Muhs|first2=D.R.|last3=Roberts|first3=H.M.|last4=Wintle|first4=A.G.|title=Last Glacial loess in the conterminous USA|journal=Quaternary Science Reviews|date=2003|volume=22|issue=18–19|pages=1907–1946|doi=10.1016/S0277-3791(03)00169-0|bibcode=2003QSRv...22.1907A|s2cid=130982847 }}</ref><ref name="esp.cr.usgs.gov">{{cite book|last1=Muhs|first1=D.R.|first2=E.A.|last2=Bettis, III|date=2003|url=https://esp.cr.usgs.gov/info/eolian/MuhsBettis2003GSAsp370.pdf|title=Quaternary loess-paleosol sequences as examples of climate-driven sedimentary extremes|journal=GSA Special Papers|volume=370|pages=53–74|doi=10.1130/0-8137-2370-1.53|bibcode=2003gsas.book...53M |isbn=978-0-8137-2370-9|archive-date=2012-02-10|access-date=2008-06-18|archive-url=https://web.archive.org/web/20120210081127/http://esp.cr.usgs.gov/info/eolian/MuhsBettis2003GSAsp370.pdf}}</ref>

During the [[Quaternary]], loess and loess-like sediments were formed in periglacial environments on mid-continental [[Shield (geology)|shield]] areas in Europe and Siberia as well as on the margins of high mountain ranges like in [[Tajikistan]] and on semi-arid margins of some lowland deserts as in China.<ref name="Frechen 2011"/>

In England, periglacial loess is also known as [[brickearth]].

===Non-glacial===
Non-glacial loess can originate from [[desert]]s, [[dune field]]s, [[playa lake]]s, and [[volcanic ash]].

Some types of nonglacial loess are:<ref>{{cite journal | last1 = Iriondo | first1 = M.H. | last2 = Krohling | first2 = D.M. | year = 2007 | title = Non-classical types of loess | journal = [[Sedimentary Geology (journal)|Sedimentary Geology]] | volume = 202 | issue = 3| pages = 352–368 | bibcode=2007SedG..202..352I | doi=10.1016/j.sedgeo.2007.03.012| hdl = 11336/114389 | hdl-access = free }}</ref>
* [[Desert]] loess produced by aeolian attrition of quartz grains;<ref>Whalley, W.B., Marshall, J.R., Smith, B.J. 1982, Origin of desert loess from some experimental observations, Nature, 300, 433-435.</ref> 
* [[Volcanic]] loess in Ecuador and Argentina;
* [[Tropical]] loess in Argentina, Brazil and Uruguay;
* [[Gypsum]] loess in Spain;
* [[Trade wind]] loess in Venezuela and Brazil;
* [[Anticyclonic]] loess in Argentina.

The thick Chinese loess deposits are non-glacial loess having been blown in from deserts in northern China.<ref>{{cite journal | last1 = Ding | first1 = Z. | last2 = Sun | first2 = J. | year = 1999 | title = Changes in Sand Content of Loess Deposits along a North–South Transect of the Chinese Loess Plateau and the Implications for Desert Variations. | journal = [[Quaternary Research]] | volume = 52 | issue = 1| pages = 56–62 | doi=10.1006/qres.1999.2045| bibcode = 1999QuRes..52...56D | s2cid = 128767602 }}</ref> The loess covering the [[Great Plains]] of [[Nebraska]], [[Kansas]], and [[Colorado]] is considered to be non-glacial desert loess.<ref name="MuhsOthers2003a"/> Non-glacial desert loess is also found in Australia<ref>{{cite journal|last=Haberlah|first=D|year=2007|title=A call for Australian loess|journal=Area |volume=39 |issue=2|pages= 224–229|doi=10.1111/j.1475-4762.2007.00730.x|bibcode=2007Area...39..224H}}</ref> and Africa.<ref name="esp.cr.usgs.gov"/>

==Fertility==
Loess tends to develop into very rich soils. Under appropriate climatic conditions, it is some of the most agriculturally productive terrain in the world.<ref>{{cite book|last=Getis|first=Arthur|author2=Judith Getis and Jerome D. Fellmann|title=Introduction to Geography, Seventh Edition|year=2000|publisher=[[McGraw Hill]]|isbn=0-697-38506-X|page=[https://archive.org/details/introductiontoge00geti/page/99 99]|url=https://archive.org/details/introductiontoge00geti/page/99}}</ref>

Soils underlain by loess tend to be excessively drained. The fine grains [[weathering|weather]] rapidly due to their large surface area, making soils derived from loess rich. The fertility of loess soils is due largely to a high [[cation exchange capacity]] (the ability of the soil to retain nutrients) and [[porosity]] (the air-filled space in the soil). The fertility of loess is not due to organic matter content, which tends to be rather low, unlike tropical soils which derive their fertility almost wholly from organic matter.

Even well managed loess [[arable land|farmland]] can experience dramatic [[erosion]] of well over 2.5&nbsp;kg/m<sup>2</sup> per year. In China, the [[Loess Plateau|loess deposits]] which give the [[Yellow River]] its color have been farmed and have produced phenomenal yields for over one thousand years. Winds pick up loess particles contributing to the [[Asian Dust]] pollution problem. The largest deposit of loess in the [[United States]] which is the [[Loess Hills]] along the border of [[Iowa]] and [[Nebraska]], has survived [[intensive farming]] and [[Land degradation|poor farming practices]]. For almost 150 years, this loess deposit was farmed with [[mouldboard plough]]s and tilled in the fall, both intensely erosive practices. At times it suffered erosion rates of over 10 kilograms per square meter per year. Today this loess deposit is worked as low till or [[no till]] in all areas and is aggressively [[terrace (agriculture)|terraced]].{{citation needed|date=October 2017}}

==Large areas of loess deposits and soils==
=== Central Asia ===
An area of multiple loess deposits spans from southern [[Tajikistan]] up to [[Almaty]], [[Kazakhstan]].<ref>{{cite journal |last=Ding |first=Z.L. |date=2002 |title=The loess record in southern Tajikistan and correlation with Chinese loess |journal=Earth and Planetary Science Letters |publisher=Elsevier |volume=200 |issue=3–4 |pages=387–400|doi=10.1016/S0012-821X(02)00637-4 |bibcode=2002E&PSL.200..387D }}, Fig. 1 (b) showing the distribution of loess, deserts, and mountains in Central Asia (adopted from [T.S. Liu, Loess and the Environment, China Ocean Press, Beijing, 1985.]). The locality of the Chashmanigar loess section is indicated by the solid arrow.</ref>

=== East Asia ===
====China====
[[File:Yellow River - panoramio.jpg|thumb|The [[Yellow River]]'s distinctive light yellow colour is due to the large amounts of loess it carries from the [[Loess Plateau]].]]
The [[Loess Plateau]] ({{zh|s=黄土高原|t=黃土高原|p=Huángtǔ Gāoyuán}}), also known as the Huangtu Plateau, is a [[plateau]] that covers an area of some 640,000&nbsp;km<sup>2</sup> around the upper and middle reaches of China's [[Yellow River]]. The Yellow River was so named because the loess forming its banks gave a yellowish tint to the water.<ref>{{cite encyclopedia|title=Huang He |url=http://www.bartleby.com/65/hu/HuangHe.html |encyclopedia=[[The Columbia Encyclopedia]] |edition=6th |year=2007 |archive-url=https://web.archive.org/web/20090605050404/http://www.bartleby.com/65/hu/HuangHe.html |archive-date=June 5, 2009 }}</ref> The soil of this region has been called the "most highly erodible soil on earth".<ref>John M. Laflen, Soil Erosion and Dryland Farming, 2000, CRC Press, 736 pages {{ISBN|0-8493-2349-5}}</ref> The Loess Plateau and its dusty [[soil]] cover almost all of [[Shanxi]], [[Shaanxi]], and [[Gansu]] provinces; the [[Ningxia Hui Autonomous Region]], and parts of others.{{citation needed|date=January 2016}}

=== Europe ===
Loess deposits of varying thickness (decimeter to several tens of meters) are widely distributed over the European continent.<ref name=":0">{{Cite journal|last1=Schaetzl|first1=Randall J.|last2=Bettis|first2=E. Arthur|last3=Crouvi|first3=Onn|last4=Fitzsimmons|first4=Kathryn E.|last5=Grimley|first5=David A.|last6=Hambach|first6=Ulrich|last7=Lehmkuhl|first7=Frank|last8=Marković|first8=Slobodan B.|last9=Mason|first9=Joseph A.|last10=Owczarek|first10=Piotr|last11=Roberts|first11=Helen M.|date=May 2018|title=Approaches and challenges to the study of loess—Introduction to the LoessFest Special Issue|journal=Quaternary Research|volume=89|issue=3|pages=563–618|doi=10.1017/qua.2018.15|issn=0033-5894|bibcode=2018QuRes..89..563S|doi-access=free|hdl=1871.1/74383097-8ffd-4d02-9616-33a106668755|hdl-access=free}}</ref> The northern European loess belt stretches from southern England and northern France to Germany, Poland and the southern Ukraine and deposits are characterized by strong influences of [[periglacial]] conditions.<ref>{{Cite journal|last1=Vandenberghe|first1=Jef|last2=French|first2=Hugh M.|last3=Gorbunov|first3=Aldar|last4=Marchenko|first4=Sergei|last5=Velichko|first5=Andrey A.|last6=Jin|first6=Huijun|last7=Cui|first7=Zhijiu|last8=Zhang|first8=Tingjun|last9=Wan|first9=Xudong|date=2014|title=The Last Permafrost Maximum (LPM) map of the Northern Hemisphere: permafrost extent and mean annual air temperatures, 25–17 ka BP|journal=Boreas|volume=43|issue=3|pages=652–666|doi=10.1111/bor.12070|bibcode=2014Borea..43..652V |issn=1502-3885|doi-access=free}}</ref> [[Southeast Europe|South-eastern European]] loess is mainly deposited in plateau-like situations in the [[Danube basin]]s, likely derived from the Danube River system.<ref>{{Cite journal|last1=Fitzsimmons|first1=Kathryn E.|last2=Marković|first2=Slobodan B.|last3=Hambach|first3=Ulrich|date=2012-05-18|title=Pleistocene environmental dynamics recorded in the loess of the middle and lower Danube basin|journal=Quaternary Science Reviews|volume=41|pages=104–118|doi=10.1016/j.quascirev.2012.03.002|issn=0277-3791|bibcode=2012QSRv...41..104F}}</ref><ref>{{Cite journal|last=Jipa|first=Dan C.|date=November 2014|title=The conceptual sedimentary model of the Lower Danube loess basin: Sedimentogenetic implications|journal=Quaternary International|volume=351|pages=14–24|doi=10.1016/j.quaint.2013.06.008|issn=1040-6182|bibcode=2014QuInt.351...14J}}</ref><ref>{{Cite journal|last1=Újvári|first1=Gábor|last2=Varga|first2=Andrea|last3=Ramos|first3=Frank C.|last4=Kovács|first4=János|last5=Németh|first5=Tibor|last6=Stevens|first6=Thomas|date=April 2012|title=Evaluating the use of clay mineralogy, Sr–Nd isotopes and zircon U–Pb ages in tracking dust provenance: An example from loess of the Carpathian Basin|journal=Chemical Geology|volume=304-305|pages=83–96|doi=10.1016/j.chemgeo.2012.02.007|issn=0009-2541|bibcode=2012ChGeo.304...83U}}</ref> In [[Iberian Peninsula|south-western Europe]], relocated loess derivatives are mostly restricted to the [[Ebro Valley]] and central Spain.<ref>{{Cite journal|last1=Boixadera|first1=Jaume|last2=Poch|first2=Rosa M.|last3=Lowick|first3=Sally E.|last4=Balasch|first4=J. Carles|date=July 2015|title=Loess and soils in the eastern Ebro Basin|journal=Quaternary International|volume=376|pages=114–133|doi=10.1016/j.quaint.2014.07.046|issn=1040-6182|bibcode=2015QuInt.376..114B|s2cid=129905410 }}</ref><ref>{{Cite journal|last1=Bertran|first1=Pascal|last2=Liard|first2=Morgane|last3=Sitzia|first3=Luca|last4=Tissoux|first4=Hélène|date=November 2016|title=A map of Pleistocene aeolian deposits in Western Europe, with special emphasis on France|journal=Journal of Quaternary Science|volume=31|issue=8|article-number=e2909|doi=10.1002/jqs.2909|issn=0267-8179|bibcode=2016JQS....31E2909B|s2cid=132258680 }}</ref>

===North America===
====United States====
[[File:Distribution of loess in North America.gif|thumb|Map showing the distribution of loess in the United States<ref name="usgs muhs">{{cite web |author= Muhs|title=Eolian History of North America: Task 2, Understand the paleoclimatic significance of loess |url= https://gec.cr.usgs.gov/archive/eolian/task2.shtml |publisher= [[USGS]] |date= 2013-02-06|archive-url= https://web.archive.org/web/20130218195902/http://gec.cr.usgs.gov/archive/eolian/task2.shtml |archive-date= 2013-02-18 |display-authors=etal}}</ref>]]
{{more citations needed section|date=January 2016}}
The [[Loess Hills]] of [[Iowa]] owe their fertility to the [[prairie]] [[topsoil]]s built by 10,000 years of post-glacial accumulation of organic-rich [[humus]] as a consequence of a persistent [[grassland]] [[biome]]. When the valuable [[A horizon|A-horizon]] topsoil is eroded or degraded, the underlying loess soil is infertile and requires the addition of [[fertilizer]] to support [[agriculture]].

The loess along the [[Mississippi River]] near [[Vicksburg, Mississippi]], consists of three layers. The ''Peoria Loess'', ''Sicily Island Loess'', and ''Crowley's Ridge Loess'' accumulated at different periods during the [[Pleistocene]]. Ancient soils, called [[paleosol]]s, have developed on the top of the [[Sicily Island, Louisiana|Sicily Island]] Loess and [[Crowley's Ridge]] Loess. The lowermost loess, the Crowley's Ridge Loess, accumulated during the late [[Illinoian (stage)|Illinoian Stage]]. The middle loess, Sicily Island Loess, accumulated during the early [[Wisconsin glaciation|Wisconsin Stage]]. The uppermost loess, the Peoria Loess, in which the modern soil has developed, accumulated during the late Wisconsin Stage. Animal remains include terrestrial [[gastropod]]s and [[mastodon]]s.<ref name="MillerOthers1">Miller, B.J., G.C. Lewis, J.J. Alford, and W.J. Day, 1985, [https://www.scribd.com/doc/18934817/1984-Louisiana-Loess-Fieldtrip-Guidebook ''Loesses in Louisiana and at Vicksburg, Mississippi. Guidebook, Friends of the Pleistocene Field Trip, 12-14 April, 1985.''] [[LA Agricultural Experimental Station]], [[Louisiana State University]], [[Baton Rouge]], [[Louisiana]]. 126 pp.</ref>

===Oceania===
====New Zealand====
Extensive areas of loess occur in [[New Zealand]] including the [[Canterbury Plains]]<ref>{{cite web|url=https://teara.govt.nz/en/canterbury-region/page-3|title=Canterbury Region|publisher= Encyclopedia of New Zealand|author=John Wilson|access-date=16 February 2020}}</ref> and on the [[Banks Peninsula]].<ref>{{cite web|author=Eileen McSaveney|title= Glaciers and glaciation - Retreating ice and the glacier legacy|publisher= Te Ara - the Encyclopedia of New Zealand|url=http://www.TeAra.govt.nz/en/photograph/10750/loess-deposits-banks-peninsula|access-date=16 February 2020}}</ref><ref>Smalley, I.J., Davin, J.E. 1980. The First Hundred Years-A Historical Bibliography of New Zealand Loess. New Zealand Soil Bureau Bibliographic Report 28, 166pp.</ref> The basis of loess stratigraphy was introduced by [[John Hardcastle]] in 1890.<ref>*Hardcastle, J. 1890. On the Timaru loess as a climate register. Transactions & Proceedings of the New Zealand Institute 23, 324-332 (on line: Royal Society of New Zealand http://rsnz.natlib.govt.nz; reproduced in Loess Letter supplement 23, November 1988).</ref>{{Primary source inline|date=September 2020}}

===South America===
====Argentina====
[[File:ArgentinaLoess.JPG|right|thumb|An [[outcrop]] of loess in [[Patagonia]]]]
Much of [[Argentina]] is covered by loess. Two areas of loess are usually distinguished in Argentina: the neotropical loess north of [[30th parallel south|latitude 30° S]] and the pampean loess.<ref name=Sagayo/>

The neotropical loess is made of silt or silty clay. Relative to the pampean loess the neotropical loess is poor in [[quartz]] and [[calcium carbonate]]. The source region for this loess is thought by some scientists to be areas of [[fluvio-glacial]] deposits the [[Andes|Andean]] foothills formed by the [[Patagonian Ice Sheet]]. Other researchers stress the importance of [[tephra|volcanic material]] in the neotropical loess.<ref name=Sagayo/>

The pampean loess is sandy or made of silty sand.<ref name=Sagayo>{{cite journal |last=Sagayo |first=José Manuel |date=1995 |title=The Argentine neotropical loess: An overview |journal=Quaternary Science Reviews |publisher=Pergamon |volume=14 |issue=7–8 |pages=755–766 |doi=10.1016/0277-3791(95)00050-X |bibcode=1995QSRv...14..755S }}</ref>

==See also==
* {{annotated link|Börde}} – North German loess regions
* {{annotated link|Gäu|Gäue}} – South German loess regions
* {{annotated link|Loam}}

==References==
; Attribution
This article incorporates CC-BY-3.0 text from the reference "Loess in Europe: Guest Editorial".<ref name="Frechen 2011">{{cite journal | last1 = Frechen | first1 = M | year = 2011 | title = Loess in Europe: Guest Editorial| journal = E&G Quaternary Science Journal| volume = 60 | issue = 1| pages = 3–5 | doi = 10.3285/eg.60.1.00 | doi-access = free }}</ref>

{{Reflist}}

==Further reading==
* Smalley, I. J. (editor) 1975. ''Loess Lithology & Genesis''. Benchmark Geology 26. Dowden, Hutchinson & Ross 454pp.
* Smalley, I. J. 1980.  ''Loess: A Partial Bibliography''.  Geobooks/Elsevier. {{ISBN|0 86094 036 5}}. 103pp.
* Rozycki, S. Z. 1991. ''Loess and Loess-like Deposits''. Ossolineum Wroclaw {{ISBN|83-04-03745-9}}. 187pp.

==External links==
{{Wiktionary|loess}}
{{commons category|Loess}}
{{Americana Poster}}
* 2006, ''[https://web.archive.org/web/20090511201317/http://www.semp.us/publications/biot_printview.php?BiotID=357 The Secret of China's Vast Loess Plateau]'' [[Suburban Emergency Management Project]], Chicago, Illinois.
* 2007, ''[https://www.ufz.de/index.php?en=35690 New European Loess Map.]'' [[Helmholtz Centre for Environmental Research]], [[Leipzig]], Germany.
* ''[https://www.museum.state.il.us/exhibits/larson/loess.html Glacial Deposits: Loess and Till.]'' [[Illinois State Museum]], [[Springfield, Illinois]].
* Briedis. C.A., 2006, [https://web.archive.org/web/20080905190943/http://www.isgs.uiuc.edu/sections/quat/loessthick-map.shtml ''Loess Thickness Map (of Illinois).''] [[Illinois State Geological Survey]], [[Champaign, Illinois]].
* Heinrich, P.V., 2008, [https://web.archive.org/web/20090325233831/http://www.lgs.lsu.edu/deploy/uploads/Loess%20Map%20of%20LA.pdf ''Loess map of Louisiana.''], Public Information Series. no. 12, [[Louisiana Geological Survey]], [[Baton Rouge]], [[Louisiana]].
* Prior, J.C., and D.J. Quade, nd, [https://web.archive.org/web/20080521133019/http://www.igsb.uiowa.edu/browse/loess/loess.htm ''The Loess Hills: A Geologic View.''] [[Iowa Geological Survey]], [[Iowa Department of Natural Resources|Department of Natural Resources]], [[Iowa City]], Iowa.
* [[U.S. Geological Survey]], 1999, ''[https://pubs.usgs.gov/info/loess/ Geology of the Loess Hills, Iowa]''
* [[U.S. Geological Survey]], 2006, ''[https://web.archive.org/web/20080513165050/http://esp.cr.usgs.gov/info/eolian/task2.html Eolian History of North America]'' Why is loess important to study?
* [https://web.archive.org/web/20080626123416/http://www.nfinity.com/~exile/loesspg.htm ''The Loess Hills of Western Iowa'']
* [http://www.mojeroztocze.pl/index.php/galeria?func=viewcategory&catid=3 ''The Loess Hills of Roztocze in Poland''] {{Webarchive|url=https://web.archive.org/web/20110102213203/http://www.mojeroztocze.pl/index.php/galeria?func=viewcategory&catid=3 |date=2011-01-02 }}

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[[Category:Pedology]]
[[Category:Glaciology]]
[[Category:Sedimentary rocks]]
[[Category:Sediments]]
[[Category:Types of soil]]
[[Category:Aeolian landforms]]