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Loess (, ; from german: Löss ) is a
clastic Clastic rocks are composed of fragments, or clasts, of pre-existing minerals In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid chemical compound with a fairly well-defined chemical composition and a specif ...
, predominantly
silt Silt is granular material A granular material is a conglomeration of discrete solid, macroscopic scale, macroscopic particles characterized by a loss of energy whenever the particles interact (the most common example would be friction when gra ...
-sized
sediment Sediment is a naturally occurring material that is broken down by processes of weathering and erosion, and is subsequently sediment transport, transported by the action of wind, water, or ice or by the force of gravity acting on the particles. ...

sediment
that is formed by the accumulation of wind-blown
dust Dust is made of s of solid . On Earth, it generally consists of particles in the that come from various sources such as lifted by wind (an ), , and . Dust in homes is composed of about 20–50% dead . The rest, and in offices, and other ...
. Ten percent of Earth's land area is covered by loess or similar
deposits A deposit account is a bank account maintained by a financial institution in which a customer can deposit and withdraw money. Deposit accounts can be savings accounts, Transaction account#Current accounts, current accounts or any of several other ...
. Loess is an aeolian (windborne) sediment, defined as an accumulation of 20% or less of
clay Clay is a type of fine-grained natural soil Surface-water- gley developed in glacial till, Northern Ireland.">Northern_Ireland.html" ;"title="glacial till, Northern Ireland">glacial till, Northern Ireland. Soil is a mixture of organic m ...

clay
and a balance of roughly equal parts
sand Sand is a granular material composed of finely divided rock (geology), rock and mineral particles. Sand has various compositions but is defined by its grain size. Sand grains are smaller than gravel and coarser than silt. Sand can also refer ...

sand
and silt (with a typical
grain size Grain size (or particle size) is the diameter In geometry Geometry (from the grc, γεωμετρία; ''wikt:γῆ, geo-'' "earth", ''wikt:μέτρον, -metron'' "measurement") is, with arithmetic, one of the oldest branches of ...
from 20 to 50
micrometerMicrometer can mean: * Micrometer (device) A micrometer, sometimes known as a micrometer screw gauge, is a device incorporating a calibrated screw widely used for Accuracy and precision, accurate measurement of components in mechanical engineeri ...
s), often loosely cemented by
calcium carbonate Calcium carbonate is a chemical compound A chemical compound is a chemical substance composed of many identical molecules (or molecular entity, molecular entities) composed of atoms from more than one chemical element, element held together ...

calcium carbonate
. It is usually
homogeneous Homogeneity and heterogeneity are concepts often used in the sciences Science (from the Latin Latin (, or , ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originall ...
and highly
porous Porosity or void fraction is a measure of the (i.e. "empty") spaces in a , and is a of voids over the total volume, between 0 and 1, or as a between 0% and 100%. Strictly speaking, some tests measure the "accessible void", the total amount of vo ...
and is traversed by vertical capillaries that permit the sediment to fracture and form vertical
bluffs Bluff may refer to: Geography * Beach ridge, a ridge running parallel to a shoreline * Bank (geography) * Cliff, a vertical rock exposure formed by erosion Places United States * Bluff, Alabama, an unincorporated community in Fayette County * Th ...

bluffs
.


Properties

Loess is
homogeneous Homogeneity and heterogeneity are concepts often used in the sciences Science () is a systematic enterprise that Scientific method, builds and organizes knowledge in the form of Testability, testable explanations and predictions about th ...
,
porous Porosity or void fraction is a measure of the (i.e. "empty") spaces in a , and is a of voids over the total volume, between 0 and 1, or as a between 0% and 100%. Strictly speaking, some tests measure the "accessible void", the total amount of vo ...
,
friable Friability ( ), the condition of being friable, describes the tendency of a solid Solid is one of the four fundamental states of matter (the others being liquid, gas and plasma). The molecules in a solid are closely packed together and c ...
, pale yellow or
buff Buff or BUFF may refer to: Film festivals * Boston Underground Film Festival * British Urban Film Festival * BUFF International Film Festival, a Swedish film festival Video gaming * Buff (video gaming), a change to a weapon or ability that de ...
, slightly coherent, typically non-
stratified Stratification may refer to: In mathematics: * Stratification (mathematics), any consistent assignment of numbers to predicate symbols * Stratified sampling , Data stratification in statistics In earth sciences: * Stable and unstable stratificati ...
and often
calcareous ''Calcareous'' is an adjective meaning "mostly or partly composed of calcium carbonate Calcium carbonate is a chemical compound A chemical compound is a chemical substance composed of many identical molecules (or molecular entity, molecula ...
. Loess grains are angular, with little polishing or rounding, and composed of crystals of
quartz Quartz is a hard, crystalline mineral composed of silica (silicon dioxide). The atoms are linked in a continuous framework of SiO4 silicon-oxygen Tetrahedral molecular geometry, tetrahedra, with each oxygen being shared between two tetrahedra, ...

quartz
,
feldspar Feldspars are a group of rock-forming aluminium Aluminium (aluminum in and ) is a with the  Al and  13. Aluminium has a density lower than those of other common , at approximately one third that of . It has a great affinity ...
,
mica Micas ( ) are a group of mineral In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid chemical compound with a fairly well-defined chemical composition and a specific crystal structure that occurs natural ...

mica
and other
mineral In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid chemical compound with a fairly well-defined chemical composition and a specific crystal structure that occurs naturally in pure form.John P. Rafferty, ed. (2 ...

mineral
s. Loess can be described as a rich, dust-like soil. Loess deposits may become very thick, more than a hundred meters in areas of Northwestern China and tens of meters in parts of the Midwestern United States. Loess generally occurs as a blanket deposit that covers areas of hundreds of square kilometers. The deposits are often tens of meters thick. Loess often stands in either steep or vertical faces. Because the grains are angular, loess will often stand in banks for many years without slumping. This soil has a characteristic called vertical cleavage which makes it easily excavated to form cave dwellings, a popular method of making human habitations in some parts of China. Loess will erode very readily. In several areas of the world, loess
ridge A ridge or a mountain ridge is a geographical feature consisting of a chain of mountains or hills that form a continuous elevated crest for some distance. The sides of the ridge slope away from narrow top on either side. The lines along th ...

ridge
s have formed that are aligned with the
prevailing wind In meteorology Meteorology is a branch of the atmospheric sciences which includes atmospheric chemistry and atmospheric physics, with a major focus on weather forecasting. The study of meteorology dates back millennia, though significant pr ...

prevailing wind
s during the last
glacial maximum#REDIRECT Ice age {{Redirect category shell, 1= {{R from move {{R from ambiguous term {{R from other capitalisation {{R unprintworthy ...
. These are called " paha ridges" in America and "greda ridges" in Europe. The form of these loess
dune A dune is a landform A landform is a natural or artificial feature of the solid surface of the Earth or other planetary body A planet is an astronomical body Astronomy (from el, ἀστρονομία, literally meaning the ...

dune
s has been explained by a combination of wind and
tundra In physical geography Physical geography (also known as physiography) is one of the two fields of geography Geography (from Greek Greek may refer to: Greece Anything of, from, or related to Greece Greece ( el, Ελλάδα ...

tundra
conditions.


Etymology

The word ''loess'', with connotations of origin by wind-deposited accumulation, came into English from
German German(s) may refer to: Common uses * of or related to Germany * Germans, Germanic ethnic group, citizens of Germany or people of German ancestry * For citizens of Germany, see also German nationality law * German language The German la ...

German
''Löss'', which can be traced back to
Swiss German Swiss German (Standard German Standard High German (SHG), less precisely Standard German or High German (not to be confused with High German The High German languages or High German dialects (german: hochdeutsche Mundarten) comprise th ...
and is
cognate In linguistics Linguistics is the scientific study of language A language is a structured system of communication Communication (from Latin Latin (, or , ) is a classical language belonging to the Italic languages, Itali ...
with the English word ''loose'' and the German word ''los''. It was first applied to Rhine River valley loess about 1821.


History of research

The term "Löß" was first described in
Central Europe Central Europe is an area of Europe Europe is a which is also recognised as part of , located entirely in the and mostly in the . It comprises the westernmost peninsulas of the of Eurasia, it shares the continental landmass of with both ...

Central Europe
by Karl Cäsar von Leonhard (1823–1824) who reported yellowish brown, silty deposits along the Rhine valley near
Heidelberg Heidelberg () is a university town in the German state The Federal Republic of Germany, as a federal state, consists of sixteen partly sovereign federated states (german: Land (state), plural (states); commonly informally / federated s ...

Heidelberg
.
Charles Lyell Sir Charles Lyell, 1st Baronet, (14 November 1797 – 22 February 1875) was a Scottish geologist who demonstrated the power of known natural causes in explaining the earth Earth is the third planet from the Sun and the only astro ...

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 In geography Geography (from Greek Greek may refer to: Greece Anything of, from, or related to Greece Greece ( el, Ελλάδα, , ), officially the Hellenic Republic, is a country located in Southeast Europe. Its population is ap ...
origin being deposited by the large rivers. It was not until the end of the 19th century that the aeolian origin of loess was recognized (Virlet D'Aoust 1857), especially the convincing observations of loess in China by
Ferdinand von Richthofen Baron Ferdinand Freiherr von Richthofen (5 May 18336 October 1905), better known in English as was a German traveller, geographer A geographer is a physical scientist, social scientist and humanist whose area of study is geography, the stu ...

Ferdinand von Richthofen
(1878). A tremendous number of papers have been published since then, focusing on the formation of loess and on loess/
paleosol In the geosciences Earth science or geoscience includes all fields of natural science Natural science is a branch of science Science (from the Latin word ''scientia'', meaning "knowledge") is a systematic enterprise that Scientific ...

paleosol
(older soil buried under deposits) sequences as archives of climate and environment change. These water conservation works were carried out extensively in China and the research of loess in China has been continued since 1954. (Liu TS, Loess and the environment) Much effort was put into the setting up of regional and local loess and their correlation (Kukla 1970, 1975, 1977). But even the chronostratigraphical position of the last interglacial soil correlating to marine
isotope Isotopes are two or more types of atoms that have the same atomic number 300px, The Rutherford–Bohr model of the hydrogen atom () or a hydrogen-like ion (). In this model it is an essential feature that the photon energy (or frequency) of ...
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 ''Figure 4'': Illustrated method of passively monitoring sand input (Keizars, 2003). Thermoluminescence is a form of luminescence that is exhibited by certain crystalline materials, such as some minerals, when previously absorbed energy from ...
(TL),
optically stimulated luminescence In physics, optically stimulated luminescence (OSL) is a method for measuring doses from ionizing radiation Ionizing radiation (ionising radiation) consists of subatomic particles or electromagnetic waves that have sufficient energy to ionizatio ...
(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 Luminescence is spontaneous emission of light Light or visible light is electromagnetic radiation within the portion of the electromagnetic spectrum that can be visual perception, perceived by the human eye. Visible light is usually defined ...
has significantly improved by new methodological improvements, especially the development of single
aliquot Aliquot ( la, a few, some, not many) may refer to: Mathematics *Aliquot part In mathematics Mathematics (from Ancient Greek, Greek: ) includes the study of such topics as quantity (number theory), mathematical structure, structure (alge ...
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. 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 enabled 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.


Formation

According to Pye (1995), 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.


Periglacial loess

Periglacial Periglaciation (adjective: "periglacial", also referring to places at the edges of glacier, glacial areas) describes Geomorphology, geomorphic processes that result from seasonal thawing of snow in areas of permafrost, the runoff from which refree ...
(glacial) loess is derived from the floodplains of
glacial A glacial period (alternatively glacial or glaciation) is an interval of time (thousands of years) within an ice age An ice age is a long period of reduction in the temperature of Earth Earth is the third planet from the Sun and the ...

glacial
braided river A braided river, or braided channel, consists of a network of river channel Channel, channels, channeling, etc., may refer to: Geography * Channel (geography), in physical geography, a landform consisting of the outline (banks) of the path of ...
s that carried large volumes of glacial meltwater and sediments from the annual melting of continental icesheets and mountain icecaps during the spring and summer. During the autumn and winter, when melting of the icesheets and icecaps 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 these floodplains consist of sediment containing a high content of glacially ground flour-like
silt Silt is granular material A granular material is a conglomeration of discrete solid, macroscopic scale, macroscopic particles characterized by a loss of energy whenever the particles interact (the most common example would be friction when gra ...
and
clay Clay is a type of fine-grained natural soil Surface-water- gley developed in glacial till, Northern Ireland.">Northern_Ireland.html" ;"title="glacial till, Northern Ireland">glacial till, Northern Ireland. Soil is a mixture of organic m ...

clay
, they were highly susceptible to winnowing of their silts and
clay Clay is a type of fine-grained natural soil Surface-water- gley developed in glacial till, Northern Ireland.">Northern_Ireland.html" ;"title="glacial till, Northern Ireland">glacial till, Northern Ireland. Soil is a mixture of organic m ...

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 River Alluvial Valley are a classic example of periglacial loess. During the
Quaternary The Quaternary ( ) is the current and most recent of the three periods of the Cenozoic The Cenozoic ( ; ) is Earth's current geological era An era is a span of time defined for the purposes of chronology or historiography, as in the regnal ...
, loess and loess-like sediments were formed in periglacial environments on mid-continental
shield A shield is a piece of personal armour held in the hand, which may or may not be strapped to the wrist or forearm. Shields are used to intercept specific attacks, whether from melee weapon, close-ranged weaponry or projectiles such as arrows, ...
areas in Europe and Siberia, on the margins of high mountain ranges like in
Tajikistan ) , image_map = Tajikistan (orthographic projection).svg , map_caption = , capital = Dushanbe Dushanbe ( tg, Душанбе, ; ; russian: Душанбе) is the Capital city, capital and largest ...

Tajikistan
and on semi-arid margins of some lowland deserts like in China. In England, periglacial loess is also known as
brickearth Brickearth is a term originally used to describe superficial windblown deposits found in southern England England is a Countries of the United Kingdom, country that is part of the United Kingdom. It shares land borders with Wales to it ...
.


Non-glacial

Non-glacial loess can originate from
desert A desert is a barren area of landscape where little precipitation occurs and, consequently, living conditions are hostile for plant and animal life. The lack of vegetation exposes the unprotected surface of the ground to the processes of ...

desert
s,
dune field A dune is a landform composed of wind- or water-driven sand. It typically takes the form of a mound, ridge, or hill. An area with dunes is called a dune system or a dune complex. A large dune complex is called a dune field, while broad, fla ...
s,
playa lake A dry lake, also known as a playa, is either a basin or depression that formerly contained a standing surface water body, which disappeared when evaporation processes exceeded recharge. If the floor of a dry lake is covered by deposits of alkali ...
s, and
volcanic ash Volcanic ash consists of fragments of rock, mineral In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid chemical compound with a fairly well-defined chemical composition and a specific crystal structure ...
. Some types of nonglacial loess are: *
Desert A desert is a barren area of landscape where little precipitation occurs and, consequently, living conditions are hostile for plant and animal life. The lack of vegetation exposes the unprotected surface of the ground to the processes of ...

Desert
loess produced by aeolian attrition of quartz grains; *
Volcanic A volcano is a rupture in the crust of a planetary-mass object A planet is an astronomical body orbit In physics, an orbit is the gravitationally curved trajectory of an physical body, object, such as the trajectory of a planet ar ...

Volcanic
loess in Ecuador and Argentina; *
Tropical The tropics are the region of Earth Earth is the third planet from the Sun and the only astronomical object known to harbour and support life. 29.2% of Earth's surface is land consisting of continents and islands. The remaining 70.8% ...

Tropical
loess in Argentina, Brazil and Uruguay; *
Gypsum Gypsum is a soft sulfate mineral The sulfate minerals are a class of mineral In geology Geology (from the Ancient Greek γῆ, ''gē'' ("earth") and -λoγία, ''-logia'', ("study of", "discourse")) is an Earth science concerned with ...

Gypsum
loess in Spain; *
Trade wind The trade winds or easterlies are the permanent east-to-west prevailing winds that flow in the Earth's equatorial region. The trade winds blow mainly from the northeast in the Northern Hemisphere The Northern Hemisphere is the half of E ...
loess in Venezuela and Brazil; *
Anticyclonic File:HadleyCross-sec.jpg, 230px, Hadley cell circulation tends to create anticyclonic patterns in the Horse latitudes, depositing drier air and contributing to the world's great deserts. An anticyclone is a weather meteorological phenomenon, pheno ...
loess in Argentina. The thick Chinese loess deposits are non-glacial loess having been blown in from deserts in northern China. The loess covering the
Great Plains The Great Plains (french: Grandes Plaines), sometimes simply "the Plains", is a broad expanse of flatland ''Flatland: A Romance of Many Dimensions'' is a satire, satirical novella by the English schoolmaster Edwin Abbott Abbott, first publi ...
of
Nebraska Nebraska () is a state State may refer to: Arts, entertainment, and media Literature * ''State Magazine'', a monthly magazine published by the U.S. Department of State * The State (newspaper), ''The State'' (newspaper), a daily newspaper ...

Nebraska
,
Kansas Kansas () is a U.S. state, state in the Midwestern United States, Midwestern United States. Its Capital city, capital is Topeka and its largest city is Wichita, Kansas, Wichita. Kansas is a landlocked state bordered by Nebraska to the north; ...

Kansas
, and
Colorado Colorado (, other variants) is a state in the Mountain West The Mountain West Conference (MW) is one of the collegiate athletic conferences affiliated with the National Collegiate Athletic Association The National Collegiate Athletic ...

Colorado
is considered to be non-glacial desert loess. Non-glacial desert loess is also found in Australia and Africa.


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. Soils underlain by loess tend to be excessively drained. The fine grains
weather Weather is the state of the atmosphere An atmosphere (from the greek words ἀτμός ''(atmos)'', meaning 'vapour', and σφαῖρα ''(sphaira)'', meaning 'ball' or 'sphere') is a layer or a set of layers of gases surrounding a p ...
rapidly due to their large surface area, making soils derived from loess rich. One theory states that the fertility of loess soils is due largely to
cation exchange capacity Cation-exchange capacity (CEC) is a measure of how many cation An ion () is a particle, atom or molecule with a net electric charge, electrical charge. The charge of the electron is considered negative by convention. The negative charge of ...
(the ability of plants to absorb nutrients from the soil) and
porosity Porosity or void fraction is a measure of the void Void may refer to: Science, engineering, and technology * Void (astronomy) Cosmic voids are vast spaces between filaments (the largest-scale structures in the universe The universe ( ...
(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
farmland Agricultural land is typically land ''devoted to'' agriculture Agriculture is the science, art and practice of cultivating plants and livestock. Agriculture was the key development in the rise of sedentary Image:Family watching televis ...

farmland
can experience dramatic
erosion In earth science Earth science or geoscience includes all fields of natural science Natural science is a branch of science Science (from the Latin word ''scientia'', meaning "knowledge") is a systematic enterprise that Scientific ...

erosion
of well over 2.5 kg /m2 per year. In China the loess deposits which give the
Yellow River The Yellow River (Chinese: , Jin: uə xɔ Mandarin Mandarin may refer to: * Mandarin (bureaucrat), a bureaucrat of Imperial China (the original meaning of the word) ** by extension, any senior government bureaucrat A bureaucrat is ...
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, the
Loess Hills flying in front of the Loess Hills at Squaw Creek National Wildlife Refuge in the Missouri River bottoms near Mound City, Missouri The Loess Hills are a formation of wind-deposited loess, loess soil in the westernmost parts of Iowa and Missouri, an ...

Loess Hills
along the border of
Iowa Iowa () is a U.S. state, state in the Midwestern United States, Midwestern region of the United States, bordered by the Mississippi River to the east and the Missouri River and Big Sioux River to the west. It is bordered by six states: Wiscon ...

Iowa
and Nebraska, has survived
intensive farming Intensive agriculture, also known as intensive farming (as opposed to extensive farming Extensive farming or extensive agriculture (as opposed to intensive farming) is an agricultural Agriculture is the science, art and practice of cultiv ...
and poor farming practices. For almost 150 years, this loess deposit was farmed with s and fall tilled, both intensely erosive. 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 terraced.


Large areas of loess deposits and soils


Central Asia

From southern
Tajikistan ) , image_map = Tajikistan (orthographic projection).svg , map_caption = , capital = Dushanbe Dushanbe ( tg, Душанбе, ; ; russian: Душанбе) is the Capital city, capital and largest ...

Tajikistan
up to
Almaty Almaty (; ; cyrl, Алматы), formerly known as Alma-Ata and Verny (russian: Верный), is the largest city in Kazakhstan, with a population of about 2,000,000 people, about 11% of the country's total population, and more than 2.7 milli ...

Almaty
,
Kazakhstan Kazakhstan ( kk, Қазақстан, Qazaqstan; russian: Казахстан, Kazakhstan), officially the Republic of Kazakhstan,; russian: Республика Казахстан, Respublika Kazakhstan, link=no) is a country located mainly in ...

Kazakhstan
, spans an area of multiple loess deposits.


East Asia


China

The
Loess Plateau The Chinese Loess Plateau, or simply the Loess Plateau, is a plateau In geology Geology (from the Ancient Greek γῆ, ''gē'' ("earth") and -λoγία, ''-logia'', ("study of", "discourse")) is an Earth science concerned with the solid ...
(), also known as the Huangtu Plateau, is a
plateau In geology Geology (from the Ancient Greek γῆ, ''gē'' ("earth") and -λoγία, ''-logia'', ("study of", "discourse")) is an Earth science concerned with the solid Earth, the rock (geology), rocks of which it is composed, and the proces ...

plateau
that covers an area of some 640,000 km2 around the upper and middle reaches of China's
Yellow River The Yellow River (Chinese: , Jin: uə xɔ Mandarin Mandarin may refer to: * Mandarin (bureaucrat), a bureaucrat of Imperial China (the original meaning of the word) ** by extension, any senior government bureaucrat A bureaucrat is ...
. The Yellow River was so named because the loess forming its banks gave a yellowish tint to the water. The soil of this region has been called the "most highly erodible soil on earth". The Loess Plateau and its dusty
soil Soil is a mixture In chemistry Chemistry is the science, scientific study of the properties and behavior of matter. It is a natural science that covers the Chemical element, elements that make up matter to the chemical compound, comp ...

soil
cover almost all of
Shanxi Shanxi (; ; Chinese postal romanization, formerly romanised as Shansi) is a landlocked Provinces of China, province of the China, People's Republic of China and is part of the North China region. The capital and largest city of the province is ...

Shanxi
,
Shaanxi Shaanxi (; , ; Chinese postal romanization, alternately Shensi) is a landlocked Provinces of China, province of the China, People's Republic of China. Officially part of Northwest China, it borders the province-level divisions of Shanxi (NE, ...

Shaanxi
, and
Gansu Gansu (, ; alternately romanized as Kansu) is a landlocked province A province is almost always an administrative division Administrative division, administrative unitArticle 3(1). , country subdivision, administrative region, subnatio ...

Gansu
provinces, the
Ningxia Hui Autonomous Region Ningxia (, ; Chinese postal romanization, alternately romanized as Ninghsia), officially the Ningxia Hui Autonomous Region (NHAR), is a landlocked Autonomous regions of China, autonomous region in the Northwest China, northwest of the China, Pe ...
, and parts of others.


Europe

Loess deposits of varying thickness (decimeter to several tens of meters) are widely distributed over the European continent. 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 Periglaciation (adjective: "periglacial", also referring to places at the edges of glacier, glacial areas) describes Geomorphology, geomorphic processes that result from seasonal thawing of snow in areas of permafrost, the runoff from which refree ...
conditions. South-eastern European loess is mainly deposited in plateau-like situations in the
Danube basin The Danube ( ; ) is Europe Europe is a continent A continent is one of several large landmasses. Generally identified by convention (norm), convention rather than any strict criteria, up to seven regions are commonly regarded as c ...

Danube basin
s, likely derived from the Danube River system. In south-western Europe, relocated loess derivatives are mostly restricted to the
Ebro Valley , name_etymology = , image = Zaragoza shel.JPG , image_size = , image_caption = The Ebro River in Zaragoza , map = SpainEbroBasin.png , map_size = , map_caption = The Ebro ri ...
and central Spain.


North America


United States

The
Loess Hills flying in front of the Loess Hills at Squaw Creek National Wildlife Refuge in the Missouri River bottoms near Mound City, Missouri The Loess Hills are a formation of wind-deposited loess, loess soil in the westernmost parts of Iowa and Missouri, an ...

Loess Hills
of Iowa owe their fertility to the
prairie Wheatfield intersection in the Southern Saskatchewan prairies, Canada. Prairies are ecosystem An ecosystem is a community (ecology), community of living organisms in conjunction with the nonliving components of their environment, interact ...
topsoil Topsoil is the upper, outermost layer of soil Soil is a mixture In chemistry Chemistry is the science, scientific study of the properties and behavior of matter. It is a natural science that covers the Chemical element, elements t ...
s built by 10,000 years of post-glacial accumulation of organic-rich
humus In soil science Soil science is the study of soil Surface-water- gley developed in glacial till, Northern Ireland.">Northern_Ireland.html" ;"title="glacial till, Northern Ireland">glacial till, Northern Ireland. Soil is a mixture of ...

humus
as a consequence of a persistent
grassland Grasslands are areas where the vegetation Vegetation is an assemblage of species and the they provide. It is a general term, without specific reference to particular , life forms, structure, extent, or any other specific or geographic ...

grassland
biome A biome is a collection of plants Plants are predominantly photosynthetic Photosynthesis is a process used by plants and other organisms to Energy transformation, convert light energy into chemical energy that, through cellular respi ...
. When the valuable A-horizon topsoil is eroded or degraded, the underlying loess soil is infertile, and requires the addition of
fertilizer A fertilizer (American English American English (AmE, AE, AmEng, USEng, en-US), sometimes called United States English or U.S. English, is the set of varieties of the English language native to the United States. Currently, American E ...

fertilizer
in order to support
agriculture Agriculture is the science, art and practice of cultivating plants and livestock. Agriculture was the key development in the rise of sedentary Image:Family watching television 1958.jpg, Exercise trends, Increases in sedentary behaviors su ...

agriculture
. The loess along the
Mississippi River The Mississippi River is the second-longest river and chief river A river is a natural flowing watercourse, usually freshwater, flowing towards an ocean, sea, lake or another river. In some cases, a river flows into the ground and b ...

Mississippi River
near Vicksburg,
Mississippi Mississippi () is a U.S. state, state in the Southeastern United States, Southeastern region of the United States, bordered to the north by Tennessee; to the east by Alabama; to the south by the Gulf of Mexico; to the southwest by Louisiana; a ...
, consist of three layers. The ''Peoria Loess'', ''Sicily Island Loess'', and ''Crowley's Ridge Loess'' accumulated at different periods of time during the
Pleistocene The Pleistocene ( , often referred to as the ''Ice Age'') is the geological Epoch (geology), epoch that lasted from about 2,580,000 to 11,700 years ago, spanning the earth’s most recent period of repeated glaciations. Before a change finally ...
. Ancient soils, called
paleosol In the geosciences Earth science or geoscience includes all fields of natural science Natural science is a branch of science Science (from the Latin word ''scientia'', meaning "knowledge") is a systematic enterprise that Scientific ...

paleosol
s, have developed in the top of the Sicily Island Loess and
Crowley's Ridge Crowley's Ridge (also Crowleys Ridge) is a geological formation that rises 250 to above the alluvial plain of the Mississippi embayment in a line from southeastern Missouri Missouri is a U.S. state, state in the Midwestern United State ...
Loess. The lowermost loess, the Crowley's Ridge Loess, accumulated during the late Illinoian Stage. The middle loess, Sicily Island Loess, accumulated during early 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 The gastropods (), commonly known as snails and slugs, belong to a large taxonomic Taxonomy (general) is the practice and science of classification of things or concepts, including the principles that underlie such classification. The term may ...
s and
mastodon A mastodon ( 'breast' + 'tooth') is any proboscidea The Proboscidea (, from the Greek Greek may refer to: Greece Anything of, from, or related to Greece Greece ( el, Ελλάδα, , ), officially the Hellenic Republic, is a country ...

mastodon
s.Miller, B.J., G.C. Lewis, J.J. Alford, and W.J. Day, 1985
''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 Louisiana State University (officially Louisiana State University and Agricultural and Mechanical College, commonly referred to as LSU) is a Public university, public Land-grant university, land-grant research university in Baton Rouge, Louisian ...
,
Baton Rouge Baton Rouge ( ; ) is the capital city of the U.S. state of Louisiana. On the eastern bank of the Mississippi River, it is the county seat, parish seat of East Baton Rouge Parish, Louisiana, East Baton Rouge Parish, the most-populous List of par ...

Baton Rouge
,
Louisiana Louisiana (Standard French Standard French (in French: ''le français standard'', ''le français normé'', ''le français neutre'' eutral Frenchor ''le français international'' nternational French is an unofficial term for a standard ...

Louisiana
. 126 pp.


Oceania


New Zealand

Extensive areas of loess occur in New Zealand including the
Canterbury Plains The Canterbury Plains is an area in New Zealand centred in the Mid Canterbury Mid Canterbury (also spelt Mid-Canterbury and mid-Canterbury) is a traditional, semi-official subregion of New Zealand's Canterbury Region extending inland from the Pac ...
and on the
Banks Peninsula in the early 19th century Banks Peninsula is a peninsula of volcanic origin on the east coast of the South Island of New Zealand. It has an area of approximately and encompasses two large harbours and many smaller bays and coves. The South Is ...
. The basis of loess stratigraphy was introduced by John Hardcastle in 1890.*Hardcastle, J. 1890. On the Timaru loess as a climate register. Transcations & 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).


South America


Argentina

Much of Argentina is covered by loess. Two areas of loess are usually distinguished in Argentina: the neotropical loess north of latitude 30° S and the pampean loess. The neotropical loess is made of silt or silty clay. Relative to the pampean loess the neotropical loess is poor in
quartz Quartz is a hard, crystalline mineral composed of silica (silicon dioxide). The atoms are linked in a continuous framework of SiO4 silicon-oxygen Tetrahedral molecular geometry, tetrahedra, with each oxygen being shared between two tetrahedra, ...

quartz
and
calcium carbonate Calcium carbonate is a chemical compound A chemical compound is a chemical substance composed of many identical molecules (or molecular entity, molecular entities) composed of atoms from more than one chemical element, element held together ...

calcium carbonate
. The source region for this loess is thought by some scientists to be areas of
fluvio-glacialFluvio refers to things related to rivers and glacial refers to something that is of ice. Fluvio-glacial refers to the meltwater Meltwater is water released by the melting of snow or ice, including glacial ice, tabular icebergs and ice shelves ...
deposits the Andean foothills formed by the
Patagonian Ice Sheetimage:Magellanglaciacion.jpg, Map showing the extent of the Patagonian Ice Sheet in the Strait of Magellan area during the last glacial period. Selected modern settlements are shown with yellow dots. Sea level was much lower than shown here. The Pat ...
. Other researchers stress the importance of
volcanic material A volcano is a rupture in the Crust (geology), crust of a Planet#Planetary-mass objects, planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and volcanic gas, gases to escape from a magma chamber below the surface. On Ear ...

volcanic material
in the neotropical loess. The pampean loess is sandy or made of silty sand.


See also

* – North German loess regions * – South German loess regions *


References

This article incorporates CC-BY-3.0 text from the reference


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. . 103pp. * Rozycki, S. Z. 1991. ''Loess and Loess-like Deposits''. Ossolineum Wroclaw . 187pp.


External links

* 2006
''The Secret of China’s Vast Loess Plateau''
Suburban Emergency Management Project, Chicago, Illinois. * 2007
''New European Loess Map.''
Helmholtz Centre for Environmental Research The work of the Helmholtz Centre for Environmental Research – UFZ (prior to 28 November 2006 UFZ-Umweltforschungszentrum Leipzig-Halle GmbH) covers both basic research and applied research. The UFZ was established on 12 December 1991. The Centr ...
,
Leipzig Leipzig (, ; Upper Saxon: ) is the most populous city in the Germany, German States of Germany, state of Saxony. With a population of 605,407 inhabitants as of 2021 (1.1 million residents in the larger urban zone), it surpasses the Saxon c ...

Leipzig
, Germany.
''Glacial Deposits: Loess and Till.''
Illinois State Museum The Illinois State Museum features the life, land, people and art of the State of Illinois. The headquarters museum is located on Spring and Edwards Streets, one block southwest of the Illinois State Capitol, in Springfield. There are three sate ...
,
Springfield, Illinois Springfield is the capital of the U.S. state of Illinois Illinois ( ) is a in the region of the . Of the fifty U.S. states, it has the , population, and the . is the state's largest city and the fifth with the capital in , located ...
. * Briedis. C.A., 2006
''Loess Thickness Map (of Illinois).''
Illinois State Geological Survey, Champaign, Illinois.
The Bibliography of Aeolian Research
* Heinrich, P.V., 2008
''Loess map of Louisiana.''
Public Information Series. no. 12, Louisiana Geological Survey,
Baton Rouge Baton Rouge ( ; ) is the capital city of the U.S. state of Louisiana. On the eastern bank of the Mississippi River, it is the county seat, parish seat of East Baton Rouge Parish, Louisiana, East Baton Rouge Parish, the most-populous List of par ...

Baton Rouge
,
Louisiana Louisiana (Standard French Standard French (in French: ''le français standard'', ''le français normé'', ''le français neutre'' eutral Frenchor ''le français international'' nternational French is an unofficial term for a standard ...

Louisiana
. * Prior, J.C., and D.J. Quade, nd
''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
''Geology of the Loess Hills, Iowa''
* U.S. Geological Survey, 2006
''Eolian History of North America''
Why is loess important to study?


''The Loess Hills of Roztocze in Poland''
{{Authority control Pedology Glaciology Sedimentary rocks Sediments Types of soil Aeolian landforms