In September 2016, the annual meeting of the International Union for Quaternary Research’s Loess and Pedostratigraphy Focus Group, traditionally referred to as a LoessFest, met in Eau Claire, Wisconsin, USA. The 2016 LoessFest focused on “thin” loess deposits and loess transportation surfaces. This LoessFest included 75 registered participants from 10 countries. Almost half of the participants were from outside the United States, and 18 of the participants were students. This review is the introduction to the special issue for Quaternary Research that originated from presentations and discussions at the 2016 LoessFest. This introduction highlights current understanding and ongoing work on loess in various regions of the world and provides brief summaries of some of the current approaches/strategies used to study loess deposits.

Pre-Quaternary terrestrial climate variability is less well understood than that during the Quaternary. The continuous eolian Red Clay sequence underlying the well-known Quaternary loess-paleosol sequence on the Chinese Loess Plateau (CLP) provides an opportunity to study pre-Quaternary terrestrial climate variability in East Asia. Here, we present new mineral magnetic records for a recently found Red Clay succession from Shilou area on the eastern CLP, and demonstrate a marked East Asian climate shift across the Miocene-Pliocene boundary (MPB). Pedogenic fine-grained magnetite populations, ranging from superparamagnetic (SP)/single domain (SD) up to small pseudo-single domain (PSD) sizes (i.e., from <30 nm up to ~1000 nm), dominate the magnetic properties. Importantly, our mineral magnetic results indicate that both pedogenic formation of SP grains and transformation of SP grains to SD and small PSD grains accelerated across the MPB in the Shilou Red Clay, which are indicative of enhanced pedogenesis. We relate this enhanced pedogenesis to increased soil moisture availability on the CLP, associated with stronger Asian Summer Monsoon precipitation during an overall period of global cooling. Our study thus provides new insights into the Miocene-Pliocene climate transition in East Asia.

The Chinese Loess Plateau (CLP) in North China is an important terrestrial archive that witnessed the environmental changes and mammal and early human evolution in Asia over the past 2.6 Ma. Establishing precise ages for the Pleistocene faunas on the CLP is critical for better understanding of these environmental, biological, and archaeological issues. Here we report a new magnetostratigraphic record that places age constraints on the Linyi Fauna on the southeastern CLP. Our investigated 170-m-thick Linyi section mainly consists of two portions: (1) an overlying eolian Quaternary loess-paleosol sequence and (2) underlying fluvial-lacustrine sand and silty clay. Paleomagnetic results suggest that the composite section records the Brunhes chron, Jaramillo and Olduvai subchrons, and successive reverse polarity portions of the intervening Matuyama chron. The Linyi Fauna is located between Jaramillo and Olduvai subchrons in the fluvial-lacustrine interval, with an estimated age of ~1.5–1.6 Ma. Combining previously dated faunas, we establish a Pleistocene magnetochronology spanning from 2.54 to 0.65 Ma for the faunas on the CLP.

The Chinese Loess Plateau, the world’s largest and oldest loess record, preserves evidence of Asia’s long-term dust source dynamics, but there is uncertainty over the source of the deposits. Recent single-grain detrital zircon U-Pb age analysis has progressed this issue, but debates remain about source changes, and the generation and interpretation of zircon data. To address this, we analyze different groupings of new and existing datasets from the Loess Plateau and potential sources. We also present the results of a first high resolution sampling, multi-proxy provenance analysis of Beiguoyuan loess using U-Pb dating of detrital zircons and detrital garnet geochemistry. The data shows that some small source differences seem to exist between different areas on the Loess Plateau. However, sediment source appears to be unchanging between loess and palaeosols, supporting a recent material recycling hypothesis. Our zircon and garnet data demonstrates, however, that Beiguoyuan experienced a temporary, abrupt source shift during the last glacial maximum, implying that local dust sources became periodically active during the Quaternary. Our results highlight that grouping data to achieve bigger datasets could cause identification of misleading trends. Additionally, we suggest that multi-proxy single-grain approaches are required to gain further insight into Chinese Loess Plateau dust sources.

In this study, we present clay mineral records from a late Pleistocene loess-paleosol sequence in the Ili Basin, Central Asia, and assess their significance for paleoclimatic reconstruction. The results show that the clay minerals are mainly illite (average 60%) and chlorite (28%), with minor kaolinite (9%) and smectite (3%). Illite was of detrital origin with no obvious modification to its crystal structure. Increases in illite content in the loess are ascribed to wind intensity rather than pedogenesis. High proportions of illite in the clay fraction, and of muscovite in the bulk samples of the paleosol units, may lead to an overestimation of the weathering intensity. Kaolinite was likely inherited from the sedimentary rocks, while chlorite might have been inherited from both sedimentary and metamorphic rocks. The paleoclimatic signals of kaolinite and chlorite were unclear, due to reworking by both fluvial and eolian systems. Smectite was more likely formed by the transformation of biotite and illite, and its variation in the loess sequence was also controlled by wind intensity; this was largely due to aggregation and is unlikely to reflect moisture changes. Although the interpretation of paleoclimate evolution may contain some uncertainties, clay mineralogy does provide the possibility of tracing dust provenance.

We report on a loess-paleosol sequence (LPS) near Remizovka, located in the northern Tian Shan piedmont of southeastern Kazakhstan. This site represents a key record for Late Pleistocene climatic fluctuations at the intersection of major northern hemisphere climate subsystems. This paper develops a synthesized dataset of previous conflicting studies at Remizovka by characterizing their (paleo)topographic context, which had remained previously overlooked. Digital elevation models, satellite images, and archival photography characterize recent topographic developments. Two well-developed pedocomplexes, which we investigate in detail and date by luminescence mark the paleotopography during Marine Oxygen Isotope Stage (MIS) 5. Peak dust accumulation rates here occurred during the middle MIS 5 and MIS 4/early MIS 3. These are partially comparable with records from neighboring regions, but not in phase with global ice volume records. This discrepancy may be related to a distinct regional environmental response to larger-scale climatic drivers and local topographic influences on dust deposition patterns. Our findings confirm the potential of the LPS Remizovka to provide high-resolution paleoclimate data for the Late Pleistocene. The three-dimensional stratigraphic reconstruction reinforces the caution required to correctly interpret loess formation processes prior to their interpretation as paleoclimate archives, and provides guidelines for a more suitable approach.

Rich ancient societies of central Asia developed on the basis of trade between East and West; their existence was dependent on natural resources that favoured agriculture. The branches of the Silk Road in central Asia clearly coincide with loess areas, where many settlements were erected based on the presence of fertile loess soil and water. The aim of the study was to analyse the environmental factors that led to the growth and decline of one of the most important Silk Road “loess towns,” ancient Panjikent, as an example of human and climatic impacts on landscape changes. The town, established in the fifth century, quickly became one of the most important cities of Sogdiana. Local loess material was used for the production of the sun-dried bricks. Rapid population growth led to deforestation and consequently increased the intensity of erosion rates and reductions in cultivation area. A period of drought near the end of the first millennium AD influenced the final abandonment of the ancient town and its relocation to the lower terrace of the Zarafshan River. A decline in natural and agricultural resources and subsequently climatic forces caused a decline in the number of cities in semiarid regions of central Asia.

This paper evaluates the possible contribution of aeolian silt to soils of Mt. Ślęża (southwest Poland). Silt loam textures are common across Lower Silesia and are often confused with silt clay loam, especially at the outer boundaries with thin loess deposits. Eight study sites with different thicknesses of silt loam mantles that are covered and/or mixed with underlying sediments were examined in the field. To test our hypothesis, we analyzed the particle size and geochemistry of representative horizons. Concentrations of major and trace elements as well as their cross ratios confirmed the aeolian origin of silt loam materials and clearly distinguished them from basal sediments. There is a clear relationship between the presence and depth of aeolian mantles and mixing zones with the type of underlying material. Furthermore, the incorporation of aeolian silt to regoliths/soils was a main agent initiating and stimulating clay translocation leading to the formation of an argic horizon below the silt mantles. Mixing aeolian silt with acid granite regoliths and further illuviation resulted in the formation of alisols, while silt contributions to serpentine sediments resulted in development of skeletic luvisols. Soils receiving very weak input of aeolian silts remain as leptosols/cambisols.

Thin loess deposits on the uplands of the southeastern Colorado Plateau have previously not been well studied. We sampled deposits and soils from trenches on Hatch Point (HP) mesa near Canyonlands National Park, Utah, and from two outcrops in Mesa Verde National Park, Colorado. At HP, the oldest buried unit yielded 2 optically stimulated luminescence (OSL) ages of 10,370 and 7555 yr; the middle unit yielded 10 OSL ages from 6220 to 1385 yr; and the youngest unit had a single age of 1740 yr. At Mesa Verde (MV), three loess units are preserved in the two outcrops we examined; 6 OSL ages range from 51 to 17 ka. At least one buried soil is present between two units with ages of about 50 and 40 ka. The ages of the loess units in both study areas correspond well with OSL-dated dune sands in Canyonlands National Park and with dune sands on Black Mesa, Arizona. Particle-size distribution combined with chemical and magnetic data indicate that HP loess was derived mostly from nearby sandstone sources with a small component of far-traveled atmospheric dust, whereas MV loess was sourced both from the nearby sandstone and the San Juan River and its tributaries.

The chronology and cause of millennial depositional oscillations within last glacial loess of the Central Lowlands of the United States are uncertain. Here, we present a new age model that indicates the Peoria Silt along the Illinois River Valley accumulated episodically from ~28,500 to 16,000 cal yr BP, as the Lake Michigan Lobe margin fluctuated within northeastern Illinois. The age model indicates accelerated loess deposition coincident with regional glacial advances during the local last glacial maximum. A weakly developed paleosol, the Jules Geosol, represents a period of significantly slower deposition, from 23,700 to 22,000 cal yr BP. A gastropod assemblage-based reconstruction of mean July temperature shows temperatures 6–10°C cooler than modern during Peoria Silt deposition. Stable oxygen and carbon isotope values (δ18O and δ13C) of gastropod carbonate do not vary significantly across the pedostratigraphic boundary of the Jules Geosol, suggesting slower loess accumulation was a result of reduced glacial sediment supply rather than direct climatic factors. However, a decrease in δ18O values occurred between 26,000 and 24,000 cal yr BP, synchronous with the Lake Michigan Lobe’s southernmost advance. This δ18O decrease suggests a coupling of regional summer hydroclimate and ice lobe position during the late glacial period.

Paleosols occur in the Driftless Area of southwestern Wisconsin because this area escaped direct Pleistocene glaciation, allowing long-term loess and colluvium accumulation in selected settings. The most complete known depositional sequence at Oil City, Wisconsin, contains eight lithologic units with five paleosols, all with normal remanent magnetism (i.e., <780 ka). Previous work characterized the stratigraphy, pedology, micromorphology, and clay mineralogy of the section. We investigate chemical weathering of the 8–63 µm silt fraction using X-ray diffraction (XRD) and elemental geochemistry by portable X-ray fluorescence (pXRF). Elemental ratios TiO2/CaO, Zr/Sr, and Rb/Sr generally align with the pedological evidence of weathering. Mineral ratios plagioclase/quartz and K-feldspar/quartz display greater scatter and less certainty in interpretation. The paleosols with Bt horizons have ratios indicating greater weathering than the modern soil. The most weathered paleosol is formed in the unnamed fourth loess unit stratigraphically below the Loveland Member. The stratigraphic position and higher degree of weathering support correlation of the fourth loess with the Yarmouth Geosol and Crowley’s Ridge Silt of the Middle Mississippi valley. Geochemical indices by pXRF are more consistent with established lithologic breaks than mineralogy by XRD. Our results support the use of pXRF for stratigraphic and weathering studies of Quaternary sediments.

Our study adds to the Quaternary history of eolian systems and deposits in western Wisconsin, USA, primarily within the lower Chippewa River valley. Thickness and textural patterns of loess deposits in the region indicate transport by west-northwesterly and westerly winds. Loess is thickest and coarsest on the southeastern flanks of large bedrock ridges and uplands, similar in some ways to shadow dunes. In many areas, sand was transported up and onto the western flanks of bedrock ridges as sand ramps, presumably as loess was deposited in their lee. Long, linear dunes, common on the sandy lowlands of the Chippewa valley, also trend to the east-southeast. Small depressional blowouts are widespread here as well and often lie immediately upwind of small parabolic dunes. Finally, in areas where sediment was being exposed by erosion along cutbanks of the Chippewa River, sand appears to have been transported up and onto the terrace treads, forming cliff-top dunes. Luminescence data indicate that this activity has continued throughout the latest Pleistocene and into the mid-Holocene. Together, these landforms and sediments paint a picture of a locally destabilized landscape with widespread eolian activity throughout much of the postglacial period.

Loess is common in the Mid-Atlantic region of the United States south of the Late Wisconsinan glacial border particularly along rivers draining the glaciated areas of Pennsylvania, New Jersey, and New York. The broadest deposits occur on the flat landscapes of the Delmarva Peninsula in Maryland where two episodes of deposition have been identified. The earlier Miles Point Loess has a limited distribution and is buried by the more widespread Paw Paw Loess. OSL and 14C dates place deposition of the Miles Point Loess during MIS 3. The well developed paleosol formed in the Miles Point Loess acts as a stratigraphic marker. The Paw Paw Loess buries Clovis age cultural materials which date deposition to the end of the Pleistocene. Loess deposits and paleosols are critical in understanding regional landscape evolution, Late Pleistocene environments, and early North American cultural history. Mapping the extent of loess in the Mid-Atlantic using the Natural Resources Conservation Service’s gSSURGO database overrepresents loess in some areas and underrepresents in others.

Loess is widespread over Alaska, and its accumulation has traditionally been associated with glacial periods. Surprisingly, loess deposits securely dated to the last glacial period are rare in Alaska, and paleowind reconstructions for this time period are limited to inferences from dune orientations. We report a rare occurrence of loess deposits dating to the last glacial period, ~19 ka to ~12 ka, in the Yukon-Tanana Upland. Loess in this area is very coarse grained (abundant coarse silt), with decreases in particle size moving south of the Yukon River, implying that the drainage basin of this river was the main source. Geochemical data show, however, that the Tanana River valley to the south is also a likely distal source. The occurrence of last-glacial loess with sources to both the south and north is explained by both regional, synoptic-scale winds from the northeast and opposing katabatic winds that could have developed from expanded glaciers in both the Brooks Range to the north and the Alaska Range to the south. Based on a comparison with recent climate modeling for the last glacial period, seasonality of dust transport may also have played a role in bringing about contributions from both northern and southern sources.