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This research provided a model of genesis of soils in North-West Siberia connecting the stages of their development to the main environmental changes over the Late Pleistocene and the Holocene. The “soil memory” showed that the studied soils had a complex polygenetic origin. A gleyed paleosol with signs of solifluction found at a depth of 2 m was most probably formed during the Marine Isotope Stage (MIS) 3 that is the Karginsky interstadial. The following stage, i.e., MIS2 – the Sartanian cryochron was characterized by the eolian sedimentation of silty material. In the Late Sartanian, new soil formation began in the silty parent material, with a strong platy cryogenic aggregation and grain size sorting. The warmer and more humid climate in the early Holocene induced clay illuviation and allowed for the formation of the argic horizon. Finally, the modern climatic conditions have caused ooidal cryogenic aggregation within upper horizons, however recent frost action has not been as strong as it was during the previous cold stage. Additionally, the modern pedogenesis included spodic and stagnic processes as well as clay mineral transformation. We suppose that such a model of soil evolution could be extrapolated to the northern Cis-Ural region, but not to the west in the Baltic region, where the dynamics of pedogenesis were different.

The Gulf of Mexico coastal plain contains one of the largest dune systems in Mexico. These dunes and particularly their paleosols contain valuable paleoenvironmental information, however this aspect has been poorly studied. Here, we present the preliminary results obtained from buried paleosols of coastal dune ridges in Veracruz with the aim to reconstruct the environmental conditions during their formation as well as the phases of stability (pedogenesis) and instability (sedimentation) of the landscape. Three profiles were studied in the areas of Punta Delgada, PD (in the north), Palma Sola, PS, and La Mancha, LM (in the south). The chronological frame was constructed by radiocarbon dating of paleosols organic matter and pedogenic carbonates, and by Optical Stimulated Luminiscence (OSL) dating for the dune sediments. For each section several paleosols levels were identified whose properties permitted the differentiation of pedogenetic trends as well as their periods of formation. Nevertheless, the three sections did not provide for a continuous record of pedogenesis and sedimentation, as most of the paleosols are truncated by erosion. PS is the most complete profile which is formed from Marine Isotope Stage (MIS) 5c to MIS 1, with especially well-developed Holocene paleosols. LM includes only paleosols developed during MIS 4 and MIS 3, and PD shows only one paleosol originated during MIS 2. Although, the chronology is not complete as it has been constructed with a few dates, we consider each section contains information from different chronological windows. The results demonstrate that the oldest paleosols formed under more humid conditions during MIS 5c to 5a and probably MIS 4. As the MIS 4 to MIS 2 paleosols contain pedogenic carbonates, we interpret drier climates or with higher evapotranspiration rates. Paleosols from the early Holocene exhibit vertic properties probably formed by seasonal climates. Soils from the Middle-Late Holocene are less developed, due to the activation of the dune sedimentation. The results found here are compared at a regional scale with the dune system in the northern Gulf of Mexico and Yucatan peninsula, revealing both synchronous and asynchronous systems of eolian dynamics. The major asynchrony relates to the Wisconsinian stage (MIS 4 to MIS 2) for which high intensity of dune development is documented in the Veracruz and northern coasts whereas no dunes of that age are found in the Yucatan peninsula.

Pedogenic carbonates are considered important indicators of past climatic changes. Their formation is due to calcite accumulation through evaporation processes in arid or semi-arid regions. Over time, secondary carbonate accumulation results in the development of calcic and petrocalcic horizons in soil profiles. In this study, we conducted an analysis of pedogenic carbonates as records of paleoenvironmental characteristics in the Teotihuacan Valley, Basin of Mexico. Micromorphological, mineralogical, and geochemical characteristics of secondary carbonates from three paleosol profiles (Cerro Gordo 1, Cerro Gordo 2, and Maseca 1) were analyzed. Pedogenic carbonates were characterized by irregular and variable carbonate crystal sizes, inclusions of soil particles, and dark or light micrite and microsparite laminations. Micromorphology and scanning electron microscopy revealed weathered plagioclase minerals as a potential source of calcium for carbonate precipitation. The 87Sr/86Sr ratio of carbonate laminar crusts and nodules from the analyses pedons in the study area also indicated that rocks of the Transmexican Volcanic Belt were the principal source of Ca and Sr for carbonates, while contribution of a far-distance eolian input was minimal. The δ13C isotopic composition evidenced a mixture of C3 and C4 plants during the Pleistocene and a transition to a higher proportion of C4 vegetal cover during the Holocene. This agreed with an increase in modeled paleo-temperature from 10.9 °C to 13.7 °C based on 18O-temperature equations. Our results support those determined for the regional paleoenvironment during the Pleistocene, the Pleistocene-Holocene transition and Mid-Late Holocene.

A method of the Holocene paleoenvironment reconstruction based on the analysis of pedobiomarkers in tell deposits is suggested. On the Yunacite tell, such a reconstruction has been accomplished applying two types of environmental records: (a) soil records documented in the profiles of two soils within the middle and lower parts of the tell and reflecting changes in the conditions of pedogenesis averaged over relatively long periods and (b) soil-sedimentary records in the cultural deposits of the Eneolithic and the Early Bronze Ages (3.5 and 2.5 m in thickness, respectively). The lower soil identified at the depth of 9.2–10.0 m was buried about 5000 cal BC (the chronology is based on calibrated 14C dates). The low humus and high carbonate contents indicate arid climate conditions in the 6th millennium BC. The middle soil at a depth of 5 m was formed for about 1500 years (4350–2850 cal BC) according to 14C data. According to chemical and micromorphological analyses, it has a higher humus content and is more leached of CaCO3, as it was formed under more humid climate conditions. A detailed time record of CaCO3 leaching processes has been revealed in the sediments of the Eneolithic and the Bronze ages that were accumulating for about 600 years in the 5th millennium BC and for about 350 years in the 3rd millennium BC. Due to the increase in climate humidity, the leaching process was intensified twice: about 4500 and 2800 cal BC. In the same two periods, especially in the former period, the proportion of residues of hydrophilic beech increases significantly, and the proportion of oak residues decreases. Similar data have been obtained by the analysis of phytoliths and pollen.

The main purpose of this work was to study and understand the interaction that occurred between an acid solution spilled from Buenavista del Cobre Mine and the soils located in the Bacanuchi River area. The question put forward in this work was: if the soils of the area were able to cushion the impact of the acid solution?. Two soil profiles were examined: Profile 8A, was located on the riverbank and was affected by the spill, whilst Profile 8B, located on the first terrace of the river valley, remained intact . Both soils profiles were chemically characterized. An additional three surface samples (0-30 cm) were taken for geoavailability tests (RBI, SB2, belonging to Profile 8B, and SB3, belonging to Profile 8A). Two further samples, representing typical unaltered soils of profiles 8A and 8B, were taken for their micromorphological study. The results showed a difference between the two profiles, with profile 8A having more acidic pH, greater electrical conductivity, and higher concentrations of Fe, Pb, Cu and As than profile 8B. The geoavailability test showed that the elements enriched in SB3 were stable and not available to the aqueous phase. The soils of Bacanuchi River contain carbonates, which interacted with the acid solution and stabilized the potentially toxic elements presents in the spilled acid solution. This interaction with carbonates promoted a new minerals formation such as gypsum and copiapite. So, the release of contaminants from soil to surface and ground waters is improbable, unless the redox conditions change or a new spill occurs releasing the potentially toxic elements (PTE) to the environment. In this work we show the importance of pedogenic carbonates in soils of arid and semi-arid environments; these carbonates represent a natural geochemical barrier, that can prevent the migration of PTEs in mining areas.

Environmental conditions and human-landscape interaction during the onset of the irrigated agriculture in Oasisamerica are not clear yet. In la Playa site (Sonora, NW Mexico), the evidences of sedentary population, land cultivation, and water management developed after the end of Altithermal period (around 4500 yr BP) include more than 550 archaeological features including hundreds of human cremations and a net of buried artificial channels. These findings were closely associated with several palaeosol levels alternating with sediments within a large alluvial fan. We studied micromorphological features, physical characteristics (color, texture, rock magnetic properties), and composition of organic matter, from three profiles (Maravillas, Zanja, and Cuatro Suelos), to reconstruct pedogenesis and sedimentary environment of the palaeosol sequences. Additional paleoenvironmental information was extracted from pollen assemblages, extracted from the Cuatro Suelos profile. The results pointed to a long period of geomorphic and climatic stability in the early-middle Holocene marked by a well-developed red Cambisol. This period was followed by an unstable interval around 4.5 kyr BP marked by severe erosion of earlier soil profiles and sedimentation of different kind: channel, floodplain, and fluvio-eolian. Later synsedimentary Fluvisols were formed showing signs of predominantly arid pedogenesis, interrupted by occasional flooding; indicators of human impact were also encountered. We conclude that the shift to irrigated agriculture as the main subsistence activity occurred during the period of major climatic and geomorphic fluctuation and then irrigation developed further under dry environment with limited water resources during the Late Holocene.

Complex geoarchaeological research of the archaeological sites with continuous long-term occupation could provide insight into environmental change and human-landscape interaction during the transition from hunter-gatherer to horticulture economy in the north-west of South America. We performed a paleopedological study in the new sections at Tequendama (rockshelter site) and Aguazuque (open-air site) two key pre-ceramic sites of the Savannah of Bogota region of Colombia, combined with traditional archaeological and paleontological investigations. The chronological scales of the sections based on a large number of 14C dates show that their occupation periods are complementary and together cover the period from the terminal Pleistocene to late Holocene. The material of the archaeological layers has a colluvial origin with large tephra input. Presence of volcanic components influence pedogenesis supporting development of granular structure, dark humus accumulation, and Andic properties that could not be used for paleoenvironmental reconstruction. Micromorphological observations however show abundant evidence of pedogenic carbonate accumulation that we interpret as evidence of gradual aridization during the middle Holocene. This conclusion is supported by the paleontological data, an upward increase of the frequency of Cavia sp. remains, and agrees with the regional palynological proxies. Aridization was the background environmental trend during the transition period from a hunter-gatherer economy to an early horticulture and plant and animal domestication.

Fragipan is a compacted but non-cemented subsurface horizon, considered as a pedogenic horizon, but the mechanism of its formation is not well understood. The main hydro-consolidation hypothesis involves a collapse of soil structure when it is loaded and wet, resulting a reorganisation of pore space. Soils with fragipan never have been marked in Russian soil maps. In the South Karelia, located in Eastern Fennoscandia (34.50921 E and 61.33186 N, 110 m asl) we studied a soil profile of Albic Fragic Retisol (Cutanic), developed in the glacial till of Last Glaciation with flat subhorizontal topography under an aspen-spruce forest. The aim of this study was to demonstrate how the fragic horizon was formed in the Retisol located in South Karelia. Observations were made in each soil horizon using micromorphological method, particle size analysis and the study of mineralogical composition of clay fraction by X-ray diffraction. The analysis of the morphological description combined with the laboratory data have led us to the conclusion that the consolidation of the fragipan occurred after the textural differentiation of the profile, following the Atlantic Optimum, and does not depend on the presence of swelling clay minerals. The well-developed argic horizon was probably formed around 6000 years ago, under climatic conditions more favourable for clay illuviation than in present time. Fragipan is supposed to be developed during the Sub-Boreal cooling.

espanolLos suelos de los oasis antarcticos, en las areas libres de hielo tanto en la costa como tierra adentro rodeadas por los glaciares terrestres o plataformas de hielo, atraen la atencion como uno de los componentes de los ecosistemas mas extremos de la Tierra. El conocimiento sobre las etapas iniciales de edafogenesis, formacion y estabilizacion del solum, interaccion entre los componentes organicos y minerales en estos suelos es todavia limitado. Hemos realizado un estudio micromorfologico de algunos perfiles de suelos superficiales, desarrollados en los sedimentos recientes no consolidados, bajo musgos y liquenes en el Oasis Schirmacher. El material mineral esta dominado por particulas de arena, de minerales primarios (cuarzo, feldespatos K-Na y micas). Los granos de cuarzo demuestran estructuras superficiales indicativas de la fragmentacion criogenica, mientras que la biotita tiene signos de alteracion quimica: intemperizacion a lo largo del clivaje, deformacion de las laminillas, perdida de los colores de interferencia y del pleocroismo. A pesar de las condiciones ambientales severas, el intemperismo incipiente genera minerales arcillosos y oxidos de hierro que se incorporan al material fino. Este ultimo forma recubrimientos discontinuos sobre los granos gruesos generando un modelo de distribucion c/f quitonico. La distribucion de los componentes finos en forma de recubrimientos sobre los granos gruesos proporciona una interaccion maxima con la humedad del suelo y la materia organica y con la generacion de micro-habitats para microorganismos. La caracteristica micromorfologica comun de los suelos estudiados consiste en una matriz compleja que combina tejidos bien conservados de musgos y liquenes y particulas minerales distribuidas entre ellos. Se concluye que los cuerpos edaficos estudiados son sin-sedimentarios: el deposito del material mineral ocurre simultaneamente con el crecimiento de las plantas primitivas. Los granos minerales estan atrapados entre los tejidos vegetales que forman el “armazon” de la matriz del suelo. Esta interaccion permite tambien la conservacion de la materia organica en la cubierta del suelo. Los suelos estudiados demuestran similitudes a las costras biologicas de otros ambientes terrestres extremos del presente y del pasado. EnglishThe soils of Antarctic oases - coastal as well as inland ice-free areas limited by ice sheet or ice shelves attract attention as a block of one of the most extreme terrestrial ecosystems of the Earth. The knowledge about early stages of pedogenesis, solum formation and stabilization, interaction between organic and mineral components in these soils is still limited. We performed micromorphological investigation of several thin soil profiles developed under mosses and lichens on the sediments deposited by meltwater in a lake depression of Schirmacher Oasis. Mineral components are dominated by sand particles of primary minerals (mostly quartz, K-Na feldspars and micas) derived from gneiss bedrock. Quartz grains exhibit surface structures indicative of cryogenic fragmentation, whereas biotite has signs of chemical alteration: exfoliation along cleavage planes, deformation of laminae, loss of interference colours and pleochroism. Despite severe environmental conditions, incipient weathering occurs that contribute clay minerals and iron oxides to the fine material. The latter forms discontinuous coatings on the coarse grains providing a chitonic c/f related distribution pattern. Arrangement of the fine components in form of coatings on coarse grains provides their maximal interaction with soil moisture and organic matter and generation of microhabitats for the microorganisms. Common micromorphological features of the studied soils is a complex groundmass which combines well preserved organic tissues of mosses and lichens and mineral particles spread among them. We conclude that the studied soil bodies are synsedimentary: fluvial (and possibly eolian) deposition of mineral material that occurs simultaneously with the growth of primitive plants. The mineral grains are trapped between plant tissues which form a framework of the soil matrix. This interlacing provides also conservation of organic material within the soil layer. Studied soils demonstrate similarities with the biological crusts of other present and past extreme terrestrial environments.

espanolLa region de Yalahau al norte de Quintana Roo, Mexico, contiene abundantes humedales de agua dulce y una historia de ocupacion Maya que abarca casi 3000 anos. Los mayores niveles de poblacion regional ocurrieron durante el periodo Preclasico tardio, del 100 AC al 350/450 DC. Los Mayas construyeron alineamientos rocosos cruzando los pantanos, y se ha hipotetizado que estas caracteristicas funcionaron para atrapar suelos y agua para la produccion de alimento y para el uso de recursos biologicos como el perifiton. Los estudios paleoambientales de un humedal de la porcion oriental de la region sugieren que la ocupacion de la region de Yalahau y la manipulacion de los humedales, corresponden con un periodo cuando el manto freatico fue menor que en tiempos modernos, creando ecosistemas de humedal que eran mas productivos para el cultivo. Este trabajo presenta resultados que aplican este modelo a escala regional (en humedales en otras partes de la region). Treinta pequenos nucleos de suelo fueron colectados de 12 humedales a lo largo de la region. Para este Proyecto, 5 nucleos de 4 humedales fueron seleccionados para los analisis que incluyen micromorfologia y fechamiento por radiocarbono. Las laminas delgadas, estudiadas bajo el microscopio petrografico, fueron usadas para identificar los varios tipos de caracteristicas presentes en los nucleos, incluyendo carbonatos, materia organica, conchas, pirita, yeso y espacio poroso. En cada nucleo, distinguimos una unidad superior dominada por carbonato micritico biogenico y una unidad inferior caracterizada por una variedad de caracteristicas de suelo unicas, como cristales espariticos de calcita, pirita, yeso y propiedades gleycas. Basado en esto, se sugiere que mientras que los procesos formadores del suelo moderno son claramente uniformes a lo largo de la region y controlados por la inundacion anual regular (~7 meses de >1 m de profundidad de inundacion cada ano), en el pasado (periodo Preclasico), la inundacion era menos regular y los ambientes de humedal fueron mas pantanosos y variados. Ademas, se sugiere que las depresiones del Preclasico encontradas por los Mayas, fueron un recurso agricola de calidad que permitio el florecimiento de la region durante el Preclasico tardio. Sin embargo, como la inundacion se volvio mas regular al final del periodo Preclasico, la region fue abandonada, solo para ser re-ocupada en el Postclasico tardio, cuando los humedales fueron explotados para recursos acuaticos, mas que para la agricultura. EnglishThe Yalahau region of northern Quintana Roo, Mexico, contains abundant freshwater wetlands and a history of Maya occupation that spans nearly 3000 years. The highest regional population levels occurred during the Late Preclassic period, from ca. 100 BC to AD 350/450. The Maya constructed rock alignments crossing wetland swales, and these have been hypothesized as features used to trap soil and water for production of food and useful biological resources such as periphyton. Paleoenvironmental studies from a wetland in the eastern part of the region suggested that occupation of the Yalahau region, and manipulation of the wetlands, corresponded to a period when the water table was lower than in modern times, creating wetland ecosystems that were most productive for cultivation. This paper presents results that apply this model at the regional scale (in wetlands in other parts of the region). Thirty short soil cores were collected from 12 wetlands across the region. For this project, 5 cores from 4 wetlands were selected for analyses including micromorphology and radiocarbon dating. Thin sections studied under petrographic microscope were used to identify the various types of features present in the core sequences including carbonates, organic matter, shell, pyrite, gypsum, and pore space. In each core, it was possible to distinguish an upper unit dominated by biogenic-micritic carbonate and a lower unit characterized by a variety of unique soil features such as sparitic calcite crystals, pyrite, gypsum, and gleyic properties. Based on this, it is suggested that while modern soil forming processes are fairly uniform across the region and controlled by regular annual flooding (~7 months of >1m deep flooding each year), in the past (Preclassic period), flooding was less regular and wetland environments were more swampy and varied. Furthermore, it is suggested that the Preclassic depressions encountered by the Maya were a prime agricultural resource that allowed the region to flourish during the Late Preclassic period. However, as flooding became more regular at the end of the Preclassic period, the region was abandoned, only to be reoccupied in the Late Postclassic when wetlands were exploited for aquatic resources rather than for agriculture.

Recent revision of the eastern boundary of the last glaciation of Eurasia opened new perspectives in the search of the paleopedological records in the north of Eastern Europe and Western Siberia. We studied paleosol-sedimentary sequences in the Upper Volga and Middle Ob basins as a regional paleoecological record for the Late Pleistocene thermochrons. Two key sections Cheremoshnik and Belaya Gora containing MIS3 and MIS5 paleosol units and additional section Koskovo 2 with polycyclic MIS3 paleosol were investigated. Their timescale are based on C14 and U/Th datings as well as on stratigraphic and paleobotanical correlations. Macro-, meso- and micromorphological observations together with fossil insects and plant macrofossil were used as paleoenvironment proxy. MIS3 paleosols show abundant redoximorphic and cryogenic features that allow interpreting them as gleyic Cryosols. Sub-fossil insects and plant macrofossil reflect the cold climate conditions. Three incipient Ah horizons in Koskovo 2 pedocomplex point to multiple phases of pedogenesis, correlative to the MIS3 paleosol levels in different sections of the Eurasian loess belt and to the major interstadials of the Middle Pleniglacial of the NW Europe MIS5 paleosols are also characterized by gleyzation and peat accumulation, in this case we suppose geomorphological control on hydromorphic pedogenesis; however paleosol in Belaya Gora has clear signs of polygenesis including the phase of clay illuviation. Insect and plant remains from the lower paleosol level of the Belaya Gora section show the transition from cold (terminal phase of MIS6) to warm first, and then to a moderately cold climate (within MIS5). The obtained results contribute to understanding of soil and landscape zonality in the largest plains of Eurasia mostly during the warm phases of Late Pleistocene.

The results of a hierarchical morphogenetic, physicochemical, and mineralogical study of the Ryshkovo full-profile texture-differentiated paleosol of the Mikulino Interglacial from the section at Aleksandrov quarry in Kursk oblast are discussed. The correlation analysis of the stratigraphy of this section with global geological records made it possible to determine the position of the Ryshkovo paleosol in the chronostratigraphic system of the Late Pleistocene and to attribute it to stage MIS 5e; the duration of pedogenesis for this paleosol was no more than 12–15 ka. The results of the study indicate that the Ryshkovo paleosol is close in its properties to the Holocene soddy-podzolic soils of the East European Plain. No direct evidences in favor of the former interpretation of this paleosol as a lessivated soil genetically close to Luvisols of nemoral broadleaved forest of Central Europe have been found. The difference between the paleosol of the Mikulino Interglacial and the modern soddy-podzolic soils is mainly related to the distribution of clay coatings. In the upper part of the illuvial horizon of Mikulino paleosol, clay coatings are few in number, and typical tongues of podzolized (albic) material are absent in the profile. At the same time, silty coatings (skeletans) are abundant even in the lower part of the illuvial horizon. In general, the Mikulino paleosol is characterized by a smaller diversity of clay pedofeatures. These differences might be related to less contrasting fluctuations of the environmental conditions in the second half of the Mikulino Interglacial, to the periodical renewal of the eluvial part of Mikulino paleosol by erosional and accumulative processes, and to the absence of anthropogenic impacts on the soil during the Mikulino Interglacial. The burying of the Ryshkovo paleosol took place due to the intense development of erosional processes induced by the contrasting climatic events at the end of the interglacial period accompanied by catastrophic forest fires and sharp cooling of the climate upon the transition to the Valdai glaciation.

Soils and sediments composing Tell Kortik Tepe (Epipaleolithic, Turkey) and Tell Yunatsite (Chalcolithic (Eneolithic), Bulgaria) have been studied with the aim to gain a better insight into their microfabrics, determine the composition of anthropogenic artifacts, and, on this basis, to analyze similarities and distinctions between these objects and the modern soils of urban areas. The methods of micromorphology, scanning electron microscopy with an energy dispersive X-ray microanalyzer, X-ray fluorometry, and other techniques to determine the chemical and physical properties of the soils and sediments have been applied. Two paleosols have been identified in Tell Yunatsite with a total thickness of 9 m: the paleosol buried under the tell and the paleosol in its middle part. Sediments of Tell Kortik Tepe have a total thickness of up to 5 m; their accumulation began at the end of Pleistocene over the surface of buried paleosol. The cultural layer of the tells consists of construction debris mainly represented by a mixture of clay and sand and of domestic wastes with the high content of phosphorus. The major source of phosphorus is calcium phosphate (apatite) of bone tissues. The abundance of various anthropogenic materials in the sediments is clearly seen in thin sections. Even in the paleosols developed within the cultural layer (the mid-profile paleosol in Tell Yunatsite), the amount of microinclusions of bone fragments, charcoal, and burnt clay (ceramics) is very high. Micromorphological data indicate that up to 50% of the layered material filling an Epipaleolithic construction in Tell Kortik Tepe consists of the anthropogenic inclusions: bone fragments, charcoal, etc. The features of pedogenic transformation are present in the sediments. Such sediments can be classified as synlithogenic soils similar to the modern Urbic Technosols. It is shown that the formation of paleosols and sediments of Tell Kortik Tepe took place under extreme environmental conditions—arid climate of the latest Pleistocene climate cooling phase (the Younger Dryas, Tell Kortik Tepe)—and intensive anthropogenic loads (tells Kortik Tepe and Yunatsite).

Paleosol-sedimentary sequences encountered in the settlements with long occupation history could provide a unique insight into the trends of landscape development and human-environment interaction over long time scales. We studied paleosols exposed by the excavations in the Kremlin of Zaraysk (Central European Russia) which were formed during the late Pleistocene and the Holocene and contain archaeological materials spanning from Upper Palaeolithic till late Medieval. Archaeological findings and numerous radiocarbon dates provide a reliable time frame for paleopedological record which we extracted from paleosols using macro- and micromorphological observations as well as physical and chemical properties and paleobotanical indicators (phytolith assemblages). The basal layer without archaeological materials presents signs of soil formation which resemble Bryansk fossil soil developed in the second half of Marine Isotope Stage (MIS) 3. The overlying archaeological stratum - one of the Gravettian cultural layers is linked to the paleosol level known as Zaraysk soil. Its age is estimated at 16 ka BP. Macro- and micromorphological features point to moderate dark humus accumulation, anthropogenic compaction and cryogenic processes at the final stages of paleopedogenesis. Poorly sorted heterogeneous composition of the mineral material with a large proportion of sand grains indicates colluvial origin of the paleosol parent material. The overlying sorted silty deposit supposes contribution of windblown material to its formation. We associate cryogenic and eolian processes at the end and after Zaraysk soil development with the cold intervals at the end MIS 2, presumably with the Oldest and Younger Dryas. The complete profile of Luvisol/Grey Forest Soil with eluvial and illuvial horizons and relict dark humus morphons is developed within the silty unit. This soil indicates long-term natural pedogenesis under first steppe and then deciduous forest vegetation during major part of the Holocene. The topsoil however is formed by clear plough horizon which points to cultivation started in the Middle Ages. Sharp boundary separates the buried Luvisol from the overlying cultural layer-Technosol developed after building of Zaraysk Kremlin in the 16th century. Technosol presents a mixture of natural soil with construction materials, especially limestone fragments. Soil units, both natural and affected by humans, are not separated one from another by an unaltered C horizon, so soil-forming processes from the upper soils penetrate into the underlying ones forming a multistory pedocomplex.

Northern Mexico is predominantly composed of moderately developed red soils that provide evidence of weathering, rubification, neoformation of clay, and pedogenic carbonate accumulation. These soils constitute a pedological unit named San Rafael Paleosol (SRP) which were developed during the late Pleistocene (MIS 2) to the middle Holocene (15,000–4500 cal years BP). These paleosols can use as a chronologic marker at a regional scale. In this paper, we present a pedogenic interpretation of the paleosol-sedimentary processes during the late Quaternary, which contributes to the reconstruction of regional paleoenvironment. The development of SRP takes place over more than 15,000 years, and this pedogenesis is interrupted by stages of strong climatic instability, causing erosion of the SRP and sedimentation, presumably during the Altithermal. The records of La Playa show that SRP is buried by fluvial sediments, which include different facies. These sedimentation events are associated with the end of the Altithermal period and evidence more active geomorphic processes. These conditions are also observed at El Gramal, where dune sediments overly the SRP. This discontinuity evidence an intense erosional/sedimentation phase. In the particular case of El Fin del Mundo site, it is observed more mesic conditions as the water table rose, creating a wetland. Much of the synchronous variation in the morphology of the paleosols (pedofacies) can be explained by differences in local geomorphological conditions. These palaoesols developed under a semi-arid climate, slightly more humid than the present one with winter dominant rains and marked seasonal changes. These assumptions are supported by soil micromorphology, physical characteristics (color, grain size distribution) and composition of total organic and inorganic carbon. Additional paleoenvironmental information is also extracted from microbiomorphic analyses and diatoms assemblages from the one profile at El Fin del Mundo site.

The MIS3 paleosol units comprise a prominent element of the loess-paleosol sequences throughout the Eurasian Loess Belt. To the north of the loess regions, the findings of MIS3 paleosols were few: it was supposed that geomorphic processes related to the extensive ice cover of the Last Glacial Maximum destroyed the earlier soil mantle. Recently, much smaller extent of continental ice in the east of Northern Europe and ice-free West Siberian Plain during MIS2 has been hypothesized, supposing preservation of MIS3 and earlier paleopedological records. We discovered in the center-north of European Russia (Upper Volga basin) and Western Siberia (Middle Ob basin), MIS3 paleosols within the Late Pleistocene alluvial and lacustrine sequences and correlated the studied profiles on the basis of macro- and micromorphological characteristics and radiocarbon datings of the paleosol organic materials. Paleosols are represented by hydromorphic profiles with Histic horizons and gleyic color pattern. Conspicuously, they are developed in the well drained geomorphic positions, where modern soils are non-gleyic. We suppose that the presence of permafrost was responsible for water logging and generation of reductomorphic soil environment. We further hypothesize a northern zone of MIS3 soil mantle, comprised of Histic and Reductaquic Cryosols different from synchronous Cambisols and Chernozems formed within loess sequences to the south.

Recent revision of the extent of Late Pleistocene glaciations in Northern Eurasia the justified search for the new paleopedological records in the center-north West Siberian Plain. We encountered paleosols in several exposures of the high alluvial terrace of the river Vakh (Middle Ob' basin), buried in the sequence of alluvial and lacustrine sediments. A paleosol dated to the end of Marine Isotope Stage (MIS) 3, Karga thermochron, was studied in detail in the key section “Zeleniy Ostrov”. The paleosol demonstrates strong morphological evidence of gleysation and accumulation of plant residues, both processes indicating water logging and a reduced environment. The modern soil on top of the exposure is a typical Podzol, formed in under conditions of perfect soil drainage and no water excess, in agreement with current geological and geomorphological conditions. We suppose that permafrost was the main factor hampering percolation and switching redoximorphic processes in the paleosol, which thus was classified as a Reductaquic Cryosol. Presence of permafrost implies colder climate than the present one. Furthermore, neutral reaction, presence of neoformed calcium carbonate and abundance of silt fraction, which points to eolian sedimentation, suggest drier conditions. However, the studied paleosols differ considerably from the synchronous Chernozems found in the loess sequences of Southern Siberia. Paleobiological proxies such as pollen, plant macroremains, phytoliths and fossil insects indicate a tundra or tundra-steppe ecosystem (possibly with some forest stands), in good agreement with the paleopedological and sedimentary records.

Stable isotopes of carbon (δ 13 C) in terrestrial geological materials (paleosol humus and carbonates) as well as fossil bones (collagen and tooth enamel) are established as highly specific records on paleoenvironmental characteristics. It was assumed that comparing the results of different types of materials on regional or local scales provides more accurate and reliable reconstructions and even opens new aspects of interpretation. This was tested by the comparison of the data obtained from the late Pleistocene paleosols and/or remains of Pleistocene megafauna in various locations in Northwestern Mexico: Sonora (paleosols formed in MIS3, MIS2 and MIS1); Central-Northern Mexico: San Luis Potosi (teeth, corresponding to MIS2 and MIS1); and Central-Southern Mexico: Puebla (paleosols corresponding to MIS3 and MIS2, and teeth associated with these paleosols), and State of Mexico (teeth, corresponding to MIS2). The results of isotopic studies are complemented with other paleoenvironmental proxies. The δ 13 C values of paleosols of Sonora is −19.8 to −16.95‰ in organic matter, and shows little difference between paleosols and Holocene soils; δ 13 C values of pedogenic carbonates are −6.4 to −4.52‰. In San Luis Potosi, the δ 13 C values of paleosol are −12.16‰ in organic matter. In Puebla, they vary from −24.6‰ in paleosols to −15.16‰ in the modern surface soil, pointing to contrasting vegetation change. The δ 13 C values in fossils range from −10.7 to 1.2‰ in SLP; of −2.73 and −2.93‰ in Puebla; and −6.5 to −1.3‰ in State of Mexico. The δ 13 C values of paleosols and analysis of megafauna in Northwest and Central-Northern Mexico matched each other, indicating mixed C3–C4 vegetation; while for Central-Southern Mexico, paleosols indicated predominance of C3 plants and megafauna indicated mixed C3–C4 composition. In general, the results indicate that in northern Mexico environmental conditions were slightly wetter than at present, while for the central area there was a large change in the environmental conditions of high humidity in MIS3 and MIS2, with a trend to drier climates in MIS1.

Volcanic activity affects past and present landscapes. Here we present a case study related to the heat impact of the Xitle lava flow on the former soil cover. The eruption occurred 1670 years B.P., in south Mexico City. The evaluated properties include those related to the “soil memory”, used as tools of paleoenvironmental interpretation in volcanic paleosols: macro and micromorphology, color, grain size distribution, magnetic susceptibility, and carbon and nitrogen contents. Changes of these properties by the heat influence are relevant for an adequate paleoenvironmental reconstruction. Two sites and three soil profiles are selected to show soil modifications by the volcanic activity. The two sites represent the following: 1) slightly transformed paleosol buried by the lava flow, but separated from it by a 10 cm thick volcanic ash layer (site Cuicuilco-ENAH); 2) moderately and strongly transformed paleosols (two profiles inside the Copilco archeological zone). One of the Copilco profiles represents a buried paleosol with a very thin (3 cm) ash layer on top, at the contact with the lava; the second profile is the most affected by the lava flow, as it is directly beneath the lava. All studied paleosols are sandy, have a low amount of organic matter, narrow C/N ratios, and very high values of magnetic susceptibility. The strongest modifications are observed in the upper horizons, which are in contact with the lava. However, the presence of the ash layer minimizes the heat effect. Despite the observed modifications, it is possible to establish three cycles of soil formation in the paleolandscape. The first, and the oldest, related to the development of a Luvisol type soil, indicates a longer time of landscape stability. During the second cycle a pedosediment with a high concentration of artifacts was formed. The last and the youngest cycle includes the Ab and the AEb horizons (present only in Copilco). They form by an Andosol type pedogenesis, which reflects a shorter time of soil development. The presence of the AEb horizon is interpreted as the result of the degradation of the Ab horizon, either due to the heat effect of the lava, or to cultivation and irrigation practiced by the pre-Hispanic communities.

In the northeastern margin of the Yucatan Peninsula, which is located in southeastern Mexico, three levels of compact carbonate crusts (calcretes) interlayered with indurated coastal calcareous sediments (calcarenites) are discernible. Since both the calcretes and calcarenites form a continuous carbonate sequence, a combined methodology (macro- and micromorphology, geochemistry and mineralogy) is used to differentiate them. Additionally, the calcrete layers are dated using the Uranium-Thorium method in order to establish a chronological framework. The carbonate differentiation and chronology are then used to establish the paleoenvironmental conditions that prevailed during calcrete formation as well as to reconstruct the coastal landscape evolution and its relation to Pleistocene sea-level changes during Marine Isotope Stages (MIS) 6 and 5. Samples of calcrete layers and calcarenites were taken from two sections in the Cancun-Tulum corridor. The lowest level of calcrete underlies a sequence of calcarenites, and the two younger levels cap the sequence. In calcretes, the micromorphology provides evidence of the presence of a relict soil with subangular blocky microstructure, root traces, and needle-fiber calcite (associated with soil-fungi interactions). In contrast, the micromorphology of the calcarenites shows ooids and bioclasts, typical of a coastal environment. Geochemically, calcretes are depleted in δ13C, compared to calcarenite, with values ranging between −2‰ and −10‰, and they have a lower proportion of rare earth elements. Calcrete mineralogy consists mainly of calcite over aragonite with a low proportion of Mg-calcite. U/Th dating indicates that the oldest calcrete was formed during the Penultimate Glacial Maximum (PGM), in MIS 6, and the two younger calcretes correspond to the Last Interglacial Period, in MIS 5c. The calcarenite formation occurred earlier, also during MIS 5. Soil formation, strong karstification and soil erosion have occurred on younger calcretes. This study suggests that these processes developed between MIS 4 to MIS 1.

Soils on volcanic ash have specific physical and chemical properties, as well as typical micromorphological characteristics. They are characterised by an extensive accumulation of short-range order Si-Al compounds, such as allophane and imogolite, formed during weathering. This results in a grouping at the highest taxonomic level as Andosols (WRB) or Andisols (USDA) and in the use of ‘andic’ designations at other levels. The microstructure evolves from coarse monic in fresh ashes over chitonic and enaulic to granular in Andosols. A weakly separated intrapedal granular microstructure may persist in Bw horizons with a blocky microstructure or with a lenticular (freeze-thaw) microstructure. In Vertisols on volcanic ash a blocky microstructure is observed. The coarse material generally includes large amounts of volcanic glass. Fresh ash can already be transformed by hydrothermal alteration, resulting in the presence of secondary products. In the first stages of pedogenic weathering, short range order Si-Al compounds are formed. Pedogenic weathering of basaltic glass can produce palagonite-like alteromorphs of allophane. Magnetite and ilmenite can persist even in strongly weathered soils. Phytoliths and fungal hyphae are generally very abundant. The b-fabric is undifferentiated as long as short range order clays and halloysite are predominant, and it becomes stipple- or mosaic-speckled when kaolinite or illite appears. Micromass coatings around coarse fragments, and internal hypocoatings in the case of pumice, develop during a fist stage of soil formation. Other textural pedofeatures, except for rare allophane coatings, are generally not present in Andosols, but appear in intergrades to Luvisols, often still composed of optically isotropic compounds. In certain duripans (Tepetate), clay coatings with opaline zones are observed. Gibbsite coatings and nodules occur in conditions with strong leaching. Opal nodules are common in many soils formed on volcanic ash.

In this paper, we present an overview of the Mexican volcanic palaeosol sequences, as a valuable tool to establish the duration of soil formation at different chronological scales. We have selected four study cases which cover time intervals from decennial, centennial, to millennial pedogenesis. The first case corresponds to the soils in El Chichon volcano, where the short interval between the eruptions gives the opportunity to study the soil formation in periods less than 500 years. In this interval, the transformation from Regosol to Andosol is observable. In El Nevado de Toluca, pedogenesis of longer duration (4000 to 6000 y), characterizes a vitric Andosol stage. In this area, the transformation of Andosol to Luvisol is also shown, in periods longer than 10,000 years. The third study case corresponds to the Tlaxcala palaeosol sequence, where pedogenesis in intervals from 10,000 to 100,000 years is observable. In this case, no Andosols are present, and a complete set of Luvisols showing different properties is found. This differentiation is not only related to the duration of the pedogenesis, but also to the climatic conditions, which lead to changes in specific properties (clay content, weathering of the primary minerals, Fed content). In this way, these soils are valuable for palaeoenvironmental reconstruction. The fourth case is related to faster pedogenesis in the volcanic regions of Mexico, where highly developed Luvisols are found, formed in intervals less than 15,000 y. In this case, the influence of a pre-weathered volcanic material as a source of clay allows the rapid transformation.

In Sonora, northwest Mexico, we have recognized the existence of paleosol units of Late Pleistocene/Early and Middle Holocene age (13,000 to 4,250 Cal years BP) at several archaeological sites with Paleo-indian occupations (e.g. La Playa, Fin del Mundo, El Bajio, El Aigame and El Arenoso). The few paleoenviromental reconstructions from the region indicate that the end of the Pleistocene was dominated by temperate climate that promoted the establishment of the first people in coexistence and interaction with the Pleistocene megafauna. The study of the spatial distribution of various soil units developed during late Pleistocene in the region provides information about local environmental settings of the initial peopling of Sonora. Several pedosedimentary sequences were analyzed in the different parts of Sonora, the age control in which was provided by archaeological and paleontological findings and/or by the radiocarbon dating of carbonates and paleosol humus. Two trends of the Late Pleistocene pedogenesis have been identified. The profiles located in the south, center and north of the state are dominated by red soils (earlier referred as Big Red in the archaeological literature) whose characteristics are represented by the Red San Rafael Paleosol (SRP). The properties of SRP in the lower part of the profile (rubification, clay accumulation, hig magnetic susceptibility, illuvial carbonates, and redoximorphic features) are indicative of a more humid environment. Above them is a late Holocene polycyclic sequence of soils with morphological characteristics displaying a more incipient development. In contrast with the sequence described above, El Arenoso, north of Caborca, show a sequence of gray soils. Two paleosols were formed in alluvial sediments. At the Cantera profile (CTP) and El Arenoso profile (ARP) paleosols are represented by Bgk horizons and evidence of weathering and clay neoformation, redoximorphic processes and illuvial accumulation of carbonates. We explain the differences of north-western profiles by specific geomorphic conditions which imply limited soil drainage and the possibility of over-wetting. These processes indicate alternating a humid environment (weathering, rubification, clay formation and redoximorphic processes); and dry periods (carbonates accumulation). Despite regional differences of the late Pleistocene paleosols, the comparison with the Holocene soils demonstrates clear trends towards desertification in the region. The first people that inhabited Sonora during the late Pleistocene found a more temperate and wetter climate than they encountered further to the north, but subsequent generations witnessed a rapid desiccation of the region with the formation of the Sonoran Desert in the early Holocene.

Based on a W–E transect through the northern loess regions of Austria, palaeoenvironmental studies were carried out in three loess–palaeosol sequences (Gunderding, Krems-Wachtberg and Stillfried B locus typicus) to complement available results in the context of a multi-methodological approach. On the base of previously published datings, our study concentrates on the MIS 3/2 transition. The results of detailed micromorphological investigations prove that palaeopedogenesis, frost processes, and sedimentation rates differ in their spatial occurrence in the loess belt of Austria. All three sequences are in line with the general trend of a reduced intensity of pedogenic and cryogenic features from western to (south-)eastern Europe, which can be explained by lower Atlantic moisture influence towards the east. Interstadial cambic horizons are well developed in the MIS 3 sequence of western Austria, whereas the eastern loess profiles only show weak pedogenesis. In all studied sequences frost processes were active during the upper MIS 3 and MIS 2. The studied MIS 2 records are characterised by tundra soils with reductaquic horizons, which is a clear sign for prolonged phases of permafrost. On the spatial scale, the sedimentation rate increases in the eastern loess regions and particularly the Krems-Wachtberg sequence in the centre of the transect experienced an exceptionally high sedimentation rate and can thus be seen as one of the most important high resolution records for the MIS 3/2 transition in European loess regions.

We present first results about an Archaic (9000–4000 BP) site, El Tebernal, in the eastern part of Mexico. At El Tebernal, a set of lithic artifacts was found associated with a paleosol (lower paleosol) and buried by an upper paleosol and a modern soil. The artifacts are made from local limestone and chert. Selected paleosol properties were evaluated (total organic carbon, grain size distribution, carbon stable isotope composition, magnetic susceptibility, and micromorphology) that provide information about paleoenvironmental conditions. The lower paleosol is composed of the following horizons: 3E, 3EB, 3BE, 3Btg1, 3Btg2, 3C while the upper paleosol only has a 2A horizon. The lower paleosol is very well developed, with in situ clay coatings, moderate weathering of primary minerals, and a matrix free of carbonates, although the alluvium in the lowermost part of the profile contains a mixture of limestone and volcanic materials. The entire sequence is covered by the modern soil mantle which is formed by an A horizon. Radiocarbon ages determined on soil organic matter from the 3Btg1 and 2A horizons were 5580 to 5320 Cal BP and 2350 to 2320 Cal BP, respectively. We interpret the age of 3Btg1 as close to the final stage of soil formation, because the organic matter content in this horizon is illuviated. Pedogenesis likely began sometime prior to the reported age in the Early Holocene. The paleosol properties indicate a long period of landscape stability ( n × 10 3 –10 4 years) under humid and temperate conditions. It is probable that volcanic events from Pico de Orizaba, located several kilometers from El Tebernal, affected this stability. One of the last eruptions produced a block-and-ash flow of dacitic composition dated at 4100 BP that contributed to the end of pedogenesis. The upper paleosol (2A horizon) as well as the modern soil contain ceramics from the Post-classic period (AD 900–1521). The profile is cut by a channel and infilled by a dark material that dates to 1140 to 970 Cal BP (AD 810–980). In consequence, the area has been strongly affected by human occupations during the Holocene. We suggest these ceramic societies caused erosion and activation of geomorphic processes.

Summary Red palaeosols of the late Pleistocene-early Holocene, both buried and non-buried, were studied recently in Sonora (NW Mexico) to reconstruct their pedogenesis as well as the palaeoenvironmental conditions. The alluvial palaeosol-sedimentary sequence of the La Playa archaeological site is a key locality for the buried San Rafael palaeosol, which exhibits a 2Ah-2Bw-2BCk-3Bgk profile and was defined as a Chromic Cambisol. Radiocarbon dates from pedogenic carbonates and charcoal set the soil formation interval between >18000 and 4300calibrated years before present (cal. year BP). Micro-morphological observations together with profile distribution of clay, carbonates, organic carbon, pedogenic iron oxides and rock magnetic properties indicated a strong eluvial-illuvial redistribution of carbonates, moderate silicate weathering and gleying in the lower horizon. Although this soil was much more developed than the overlying syn-sedimentary late Holocene Fluvisols, clay mineral composition and stable carbon isotope signatures of humus and carbonates were similar in both soils. We suggest that pedogenesis of the San Rafael palaeosol took place under a slightly more humid climate and relative geomorphic stability. This agrees with the regional palaeoclimate reconstruction, which indicates a moister climate during the Late Wisconsin glaciation (MIS 2). An abrupt termination of the San Rafael pedogenesis marked by disturbance and aridization features in the Ap horizon of the palaeosol could be linked to a global drought around 4200years cal. year BP. Surface Chromic Cambisols in northern Sonora show similar pedogenetic characteristics to the buried red palaeosols of La Playa. They appear to be a relict component of the present day soil mantle.

In this work, we present the results of a soil study in the Teuhtli volcano, located to the south of the Basin of Mexico with the aim to understand the pedogenetic pathways and the evolution of the landscape dynamics. Two different types of soil prof iles were sampled: in “conserved” areas, with less anthropogenic influence and in sites with intense agriculture activities since pre-Hispanic times. The three conserved prof iles are located in different landscape positions: the Cima prof ile in the summit, the Ladera prof ile in the high slope, and the Yotecón in a lower position of the piedemont. The agriculture prof iles are La Cruz, La Era and El Llano, situated in the foothill. Properties in both kind of soils are similar, however, in agriculture sites, structure (evaluated in macro and microscale) is weaker, total organic carbon content is smaller and bulk density is higher. Both soils show two main pedogenetic processes: andosolization and carbonate formation. Despite the age of the parent material (36 000 years), the Andosol phase has not been lost. This is because of the geomorphological dynamics of the zone, in which the processes of erosion and colluviation promote soil loss, restarting the pedogenetic clock. The detection of lithological discontinuities (by the Ti/Zr ratio) documents these processes. By the other hand, the formation of pedogenic carbonates is governed by the seasonal conditions of drought. The age of these carbonates places their formation in the mid-Holocene, an epoch for which drier conditions are detected in other sites of the Basin of Mexico. The agricultural land use has also promoted morphological, chemical and physical changes in the soils. The continuous tillage of the sites has prevented the soils from developing. This could have a negative effect on the fertility of those soils currently used to sustain the peri-urban agroecosystems of Mexico City.

A fragipan is a diagnostic subsurface soil, not a cemented horizon, which is characterised by high density, and so restricts root penetration and water percolation. Although fragic horizons are considered to be pedogenic, the exact genesis of this phenomenon is not well understood. Quantitative study of pore space characteristics in a profile with a fragipan could help in understanding its origin and its pedogenic links to the other diagnostic horizons. Micromorphological and morphometric study of the porous network in soil thin sections and computed tomography in an Albic Fragic Retisol (Cutanic), formed in glacial till of Valday (Wurm) Glaciation in the South Karelia region in the north of Russia, showed a differentiation of pores by shape and distribution for each soil horizon controlled by the type of soil-forming processes. In particular we detected a difference in pore space organisation in the fragic EBx compared with other horizons. The pore space in the EBx was mainly represented by closed micropores, spread homogenously in the soil horizon body, independent of fissure and packing pores. Thus we propose that the pore system in this horizon was heterochronous, with micropores formed at the time of structural collapse and the fissures and other pores formed later.

Although archaeologists have generally assumed that the ancient landscape in the Teotihuacan Valley was somewhat similar to the present day, recent research has documented large-scale modification of the soil by accelerated human-induced erosion–sedimentation processes from the pre-Hispanic and Colonial periods up until the present. Consequently, the Formative and Classic period soil (approximately 400 B.C.–A.D. 650) is buried in most of the Teotihuacan Valley. Recent soil survey and archaeological excavation have shown that the modern soil horizon differs remarkably from the Teotihuacan soil horizon. In this paper, we present a pedogenic interpretation of the Teotihuacan paleosol referred to as the Black San Pablo Paleosol (BSPP), which contributes to the reconstruction of regional paleoenvironment and human-induced processes. The BSPP has been identified in both natural landscapes and under Classic period Teotihuacan buildings, as well as inside the fill of the Moon Pyramid. Maize pollen and phytoliths testify to the soils use for agriculture, whereas diatoms and phytoliths indicate irrigation practices. These results are supported by soil micromorphology. The evaluation of agronomic properties of the BSPP indicates qualities suitable for agriculture; however, water infiltration is low, indicating possible problems with seasonal water saturation.

Two paleosol-sedimentary sequences Koskovo and Puzbol developed within the nearest periglacial zone of Valday glaciation of the East European Plain (56.7°–58.5° N, the Upper Volga River basin) were studied to reconstruct soil mantle and landscape evolution since Marine Isotope Stage (MIS) 3. The sequences are formed on terraces at 130–141 and 172 m a.s.l., constituted by ancient (Early Valday (Wurm) or Late Moscow (RissII)) lake clayey sediments. The buried paleosols are represented by system of horizons Hb–G3b (Histosol), Agb–G3b and AGb horizon (Umbric Gleysol). The 14 C age of the paleosol humus and peat varied between 50,300–39,700 cal. BP. These paleosols were developed under forest-tundra and pine-spruce forests with the meadow plant communities and the areas of swampy vegetation according to palynological data from Puzbol. They represent the northernmost occurrence of the MIS3 fossil soil in Europe dominated by the features of gleyzation, cryogenic aggregation, cracking, and humus and peat formation. Clay coatings in the Middle Valday paleosols and pedosediments are products of Holocene pedogenesis. The upper lithological layers covering the MIS3 paleosols are loess-like (mantle) loams underlain by clayey Late Pleistocene lake deposits. They mark the presence of wide extraglacial lakes with existed within the Upper Volga basin during the maximum advance of the Valday glaciation (MIS2). Based on the stratigraphy of the studied sections, the highstands of these Late Quaternary lakes might exceed ≈170 m a.s.l. For the first time it was possible to date the age of humus-clay coatings developed in the Bthk3 horizon (c.1.6–2.0 m) of Puzbol where in the upper part of the section the Cutanic Albeluvisol formed. The Early Middle Holocene age of humic acid of humus-clay coatings (≈10,900 cal. BP) and carbonate nodules 7500–8180 cal. BP refer to the first stage of pedogenesis of this polygenetic soil, which occurred from pre-Boreal to the Atlantic period, and was characterized by dark humus accumulation and carbonate precipitation in a poorly drained landscape. The 14 C age of the fulvic acids of these coatings (≈6130 cal. BP) is indicative of the beginning of the second stage, dominated by clay illuviation under a better drained, leaching environment.

The Alexandrovsky quarry exposure (near Kursk, central European Russia) represents one of the most complete and detailed records of paleosols, colluvial sediments and loess for the last glacial-interglacial cycle in Eastern Europe. The buried toposequence of Mikulino (Eemian) paleosols, developed on a gully slope cut in the Dnepr (Riss) loess and overlain by Early Valdai (Wurmian) colluvium, was subjected to detailed morphological study. The paleosol on the upper slope is an Albeluvisol that contrasts from the Holocene Chernozem. Analysis of thin sections of the Albeluvisol demonstrated that elluvial features – concentrations of bleached silt in the pores and in the groundmass – dominate not only in E and EB but also in the Bt 1 horizon. They also penetrate into lower Bt 2 and Bt 3 horizons where they combine with illuvial clay pedofeatures. The paleosol profile at the bottom of the gully shows synsedimentary development with several A, AE and E horizons reflecting several phases of geomorphic activity as a response to a complex environmental history during the last interglacial. The shift from dark humus accumulation under grasslands towards forest pedogenesis dominated by clay illuviation and stagnic processes comprised the major trend of the Mikulino (Eemian) soil evolution.

Factors controlling spatial soil organization have recently attracted the attention of soil scientists because they can contribute to regional management of soil resources. We present here a case study in the Glacis de Buenavista (Mexico), an extended volcanic piedmont, in order to develop an integral understanding of its soil cover as a product and, at the same time, as a record of the main stages of landscape evolution. Three phenomena were considered: Luvisol and Vertisol type soils, and pedosediments, all of them analyzed in terms of their development degree (clay content, macro and micromorphology, selective extractions of Fe (Fed, Feo), silicon (Sio) and aluminum (Alo), weathering index and clay mineralogy). Luvisols, represented in the Ahuatenco, Mexicapa and Buenavista sections, are located in the northern and central part of the area. They are red-clayey, polygenetic soils that show strong weathering (with high kaolinitic clay content and high weathering index values), clay illuviation, and reductomorphic processes, combined with vertic features in some parts of the profiles. Vertisols dominate the central and southern portion of the Glacis. They exhibit cracking, angular blocks with wedge-like shapes, slickensides and stress-cutans. The pedogenesis of the Vertisol type is clearly associated with the presence of smectitic minerals in the clay fraction as a product of neoformation. Factors controlling this pedodiversity are: relief, which affects bioclimatic differentiation within the studied landsurface and defines the lateral redistribution of moisture and dissolved substances; and time. Luvisols represent a longer pedogenetic phase that started in the Late Pleistocene, according to the age of buried paleosols, while Vertisols mainly originated in the Late Holocene (according to the age of buried organic horizons). Pedosediments are located in the central area of the Glacis. Here, past and present geomorphic processes interact to produce the greatest soil diversity. The recent human-induced erosion partly destroyed polycyclic Luvisols and exposed ancient subsurface pedosedimentary strata. At the same time it produced patches of unconsolidated pedosediments consisting mostly of redeposited Luvisol materials.

article i nfo At the Tongoy palaeobay in north-central Chile, a series of beach ridges developed during seaward progradation that took place after the MIS 11 sea-level highstand (412 ka). The microrelief left by this succession of beach ridges has been well preserved from erosion due to the development of a calcrete (petrocalcic horizons), which was resistant to the chemical and physical weathering that characterized the area during humid phases of the late Pleistocene and middle Holocene. Macro- and micro-morphological analysis shows that the calcrete is of pedogenic origin and formed during two stages: in the first stage a massive (beta) calcrete developed, followed during the second stage by a laminar (alpha) calcrete. Each event in the development of the calcrete was intimately related to the foregoing process, mainly due to changes in the permeability of the profile horizons. During the first stages of development, organisms played an important role in the precipitation of calcite, which made the calcrete less permeable and favored the accumulation of ponded water during the wet season. As a result of this increased humidity, calcium carbonate with a laminar structure was precipitated. The development of the calcrete was also intimately associated with the evolution of the drainage network, which is characterized by a trellis pattern of tributaries parallel to the beach ridges. This study demonstrates the importance of soil genesis in the geomorphological evolution of landscapes.

A paleosol sequence in the Teotihuacan valley was studied in order to reconstruct landscape evolution during the Late Pleistocene–Holocene, in a cut belonging to a river gully (San Pablo). The sequence is constituted by 4 pedostratigraphic units labeled as SP1–SP4, separated by volcanogenic-alluvial/colluvial sediments. SP4, at the base of the sequence, has a prismatic structure, clay cutans and vertic features. SP3 shows abundant signs of zooturbation (krotovinas) and clay cutans. Both paleosols are interpreted to have formed in stable, humid, forest landscapes, during Marine Isotope Stage 3 (MIS3). However, towards the end of MIS3, these conditions alternated with the periods of contrasting seasonal climate. The overlying SP2 unit is a pedocomplex demonstrating 2 petrocalcic horizons combined with redoximorphic features. The pedocomplex merges laterally with gradually stratified gleyic channel deposits (gravels in the base to fine sand and silt in the top). The age of the lower caliche is 24,000 BP, and thus SP2 formed during MIS2, including the Last Glacial Maximum (LGM). The environmental conditions during LGM are mostly dry with stages of high humidity evidenced by gleyic processes and fluvial activity. At the end of the Pleistocene, the landscape becomes highly unstable, and pedogenesis is replaced by sedimentation. New paleochannels cut through the previously formed paleosols. These channels are infilled by poorly sorted sediments with no gradation. The configuration of all paleochannels is NNE–SSW, nearly at 90° to the modern San Pablo river flow. Geomorphic stability during the early and middle Holocene allowed the development of SP1 in a dry environment. The A horizon of this paleosol has been dated at 2900 BP. It is well developed with strong vertic features. This paleosol is thought to have formed the soil cover when the Classic period Teotihuacan culture flourished in the valley, between the first and third centuries AD. Soils above SP1 are poorly developed and erosion/deposition processes predominate over pedogenesis. Recent landscape instability is due to human activities that intensified erosion processes during the Classic and, especially, the Postclassic and Colonial periods.

The origin of red clayey soils developed on limestones has been largely questioned. We have analyzed thick red soils on Eocene-Pliocene limestones of the Yucatan peninsula (with detail in the Kantunil Kin area). The morphological, geochemical and mineralogical characteristics were interpreted as a record of pedogenesis and geomorphic dynamics during the Quaternary. Sand fraction mineralogy, the Zr/Ti ratio and ternary diagrams of Trace elements (Ti-Y-Zr, La-Th-Sc and Zr-Th-Sc) indicated a mixed origin of the soil parent material; volcanic and granitic/metamorphic components, redeposited by eolian transport. Within the soil matrix, primary minerals were transformed by weathering and caused desilication with the accumulation of kaolinitic clay. Reworked pedofeatures were originated from different soil bodies eroded. In the lower part of the profiles, we described the zone of carbonate leaching front, were the clay translocation in suspensions and posterior coagulation is more probable than the migration of elements in solutions and posterior synthesis.

The pedogenetic and geomorphic processes controlling soil development in tropical karstic landscapes, are still poorly understood. We have discovered and studied thick pedosediments in karst pockets, developed in Late Pleistocene lithified calcareous dunes (eolianites), in the NE coast of the Yucatan peninsula. The morphological geochemical and mineralogical characteristics of the pocket fills, were interpreted as a record of pedogenesis and geomorphic dynamics, that shaped the soil mantle during the Holocene. Sand fraction mineralogy and the Zr/Ti ratio, indicated a mixed origin of the soil parent material; volcanic and granitic/metamorphic components, redeposited in the lithoral and coastal environments were identified. Within the soil matrix, primary minerals were transformed by weathering and caused desilicification, accumulation of clay (hydroxy-interlayered vermiculite and kaolinite) and dithionite–citrate–bicarbonate extractable iron oxides (Fed). Reworked pedofeatures indicative of clay illuviation and redoximorphic processes were observed. This set of processes points to a continuous phase of humid pedogenesis, several thousand years long in the Early–Middle Holocene. However, the development of thick recalcified pedosediments in the pockets, contrasting with the thin background Rendzinas requires active soil redeposition, during a late phase of geomorphic activity. The available Accelerator Mass Spectrometry (AMS) radiocarbon date indicates that the switch of the erosion/sedimentation processes could be related to ancient Maya land-use impact.

At present, many parts of river valleys, including floodplains, are being actively used for urban construction. This leads to the disturbance of normal functioning of the valleys; alluvial deposits and soils become buried under the thickness of various anthropogenic materials. Four profiles of typical urban soils (urbanozems) developed on the floodplain of the Moskva River and its small tributaries have been studied. The macro- and micromorphological characteristics (including data of submicroscopic studies) and the chemical and physicochemical properties of these soils are analyzed. It is shown that the influence of ground-water on the anthropogenically transformed soils of floodplains and low terraces is preserved even upon the cessation of regular flooding. The substitution of urban pedosedimentogenesis for alluvial pedosedimentogenesis has a gradual character with a transitional stage of simultaneous occurrence of both processes. Clayey and clayey-calcareous infillings in the middle-profile horizons and newly formed phosphates of iron and calcium in the lower horizons affected by the groundwater can be considered typical diagnostic features of the urban-alluvial pedogenesis.

The soils of montane cloud forests (MCF) are still insufficiently studied. A number of researchers report Podzols to be the main soil group for MCF ecosystems; however, a great deal of contradictory data exists. We studied an altitudinal sequence of soils formed on ferrous chlorite shale under natural MCF vegetation in Sierra Juarez, Southern Mexico, from 1500 to 2500 m asl. The soils of the upper part of the toposequence were Folic Stagnic Podzols, with inclusions of Folic Stagnosols in local depressions, while the soils of the lower part of the toposequence were Folic Cambisols (Humic, Hyperdystric). All the soils in the toposequence were extremely acid, and had thick organic surface horizon. Mineral horizons of all soils were poor both in exchangeable and total reserves of bases; the bases were concentrated mainly in organic topsoil. With decreasing altitude both the thickness of albic horizons, the depth of the maximum acid oxalate-extractable Fe and Al concentrations, and the difference in clay content between the eluvial and illuvial horizons decreased. In the upper part of the toposequence the composition of soil clays was similar to that of parent material (chlorite and mica), with some mixed-layered 2:1 minerals. However, gibbsite and kaolinite were also present in the soils of the other site within the same upper MCF belt. The phenomenon was ascribed to parent material heterogenity. In the medium and lower parts of the toposequence gibbsite and kaolinite were the dominant minerals. We consider that the main pedogenic processes in the study area are raw humus accumulation, weathering in situ, podzolization, and iron reduction due to water stagnation in mineral topsoil. The intensity of weathering decreases, while the extent of water stagnation increases with altitude. To a great extent the genesis and altitudinal distribution of the soils in the MCF depends on parent material.

High rates of pedogenesis on unconsolidated volcanic materials imply the accelerated generation of the soil memory. The purpose of this research was to extract the high resolution (centennial scale) paleopedological records from the Late Holocene paleosols of the El Chichon volcano formed during the last 2000 years. We studied buried monogenetic Andosols on the dated tephras and a pedocomplex formed from a set of thin ash layers deposited on older Acrisol derived from shales. Particle size distribution, DCB-extractable Fe, oxalate-extractable Fe, Al and Si, sand and clay mineralogy, organic carbon content and stable C isotope composition in humus were evaluated and interpreted as the elements of the soil memory. However, some differences were found in properties of two buried soils, especially in the kind of A horizons. We attribute such differences of individual Andosols to be caused by ancient human impact because it has been demonstrated that humid conditions persisted during the last 1300 years. Thus the drought that was supposed to provoke the collapse of the Maya civilization at the end of I millennium A.D., should have been a short-term event, below the resolution of this paleopedological record. The Andic Acrisol pedocomplex demonstrated the domination of the humid tropical climate over longer time intervals (probably major part of the Holocene) with possible minor dry episodes.

Despite a vast literature concerning magnetic properties of loess sequences, we still do not fully understand how magnetic components and properties are related to particular soil-forming processes that can vary with each type of genetic horizon. In order to establish the role of lithogenic factors in the link between magnetic properties and soil-forming processes, we carried out a study of two complete profiles of buried interglacial Luvisols, one formed in loess in Russia (Alexandrovsky quarry) and the other in volcaniclastics in Mexico (Barranca Tlalpan). In both profiles, soil genetic horizons have contrasting differences of their magnetic properties. In the Alexandrovsky profile, the magnetic susceptibility (χ) is enhanced in the paleosol compared to parent material. In the Barranca Tlalpan sequence, χ enhancement is absent in the soil profile. Increase of fine-grained magnetic components in the soil is attributed to neoformed minerals. However, this process cannot compensate for the loss of lithogenic magnetic minerals in any of the genetic horizons, and the resulting trend is χ depletion in the whole soil profile. The pedogenic environment of eluvial horizons in both Luvisols is destructive to all magnetic components, both primary and secondary. Higher concentrations of antiferromagnetic components (hematite and goethite) found in E horizons are related to redoximorphic processes.

Both mature and underdeveloped soils are present in tropical mountainous landscapes. The spatial arrangement of mountainous soils is ascribed mainly to geomorphologic processes. We studied two soil toposequences (one on a convex, and the other on a concave slope with a gradient 40–60%) at the coffee-growing farm La Cabana, situated in the mountains of the Sierra Madre del Sur, southern Mexico. Mature (Alisols) as well as moderately developed (Luvic Phaeozems) and underdeveloped soils (Fluvic and Skeletic Phaeozems) were detected in the study area. The sequence of sediments and soils is unusual for a classical soil catena. Buried clayey reddish soils are present on the shoulder of a slope; colluvial sediments with weakly developed soils form convex and concave footslopes. The peculiarity of the slopes and spatial distribution of soils in the studied toposequences were ascribed to intensive linear erosion (due to tectonic uplift), seismically induced landslides, and K-cycles of laminar erosion. The diversity of sediments leads to considerable variation in soil texture and mineralogical composition, and, thus, to the diversity of soil properties, which is considered to be a positive feature of a landscape.

Surface and buried Andosols and buried Luvisols of the Nevado de Toluca Late Quaternary tephra-paleosol sequence (Central Mexico) were studied to show whether these soils present an evolutionary sequence and to determine the pedogenic mechanisms and environmental factors involved in the evolutionary process. Micromorphological observations and mineralogical composition of fine sand and clay fractions were used to detect type and succession of soil-forming process. Some of the buried Andosols, defined as “intergrade” Andosols, have a predominantly blocky structure, humus-depleted areas, redoximorphic features and thin clay coatings in Ah horizons. Clay fractions of buried Andosols contain halloysite besides amorphous components, whereas in modern Andosols, allophane is dominant. Luvisols have micro-areas with granular structure and abundant phytoliths in the groundmass of Bt horizons assumed to be the relict Andosol features. Luvisol clay fractions are dominated by halloysite and kaolinite. Primary minerals show micromorphological weathering features in all studied soils being stronger in Luvisols; however, even in Luvisols, sand fractions consist mostly of unstable volcanic silicates. We hypothesise that the studied profiles form an evolutionary sequence: Andosols–“intergrade” Andosols–Luvisols; the soil transformation is supposed to be linked to progressive crystallisation of 1:1 clay minerals. Comparing the Nevado de Toluca paleosol properties with the existing data on volcanic soil climo- and chronesequences and assessing the regional paleopedological and lacustrine records of Quaternary paleoclimates, we concluded that wet/dry climatic oscillations took place during the formation of the studied paleosols. Rapid crystallisation of 1:1 minerals occurred during dry phases, which speeded up the Andosol to Luvisol transformation and made it independent from the primary mineral weathering status. The Andosol to Luvisol transformation accelerated by climatic fluctuations is thought to be a common soil evolutionary pathway in the subtropical and tropical regions of recent volcanism, which suffered contrasting precipitation oscillations in the Quaternary.

Surface Terrae Rossae (Rhodoxeralfs), and a Terra Fusca (Petrocalcic Palexeralf) developed on mid-Quaternary calcarenites in the moister region of Rabat, show substantial pedogenic formation of clay minerals, particularly kaolinite, mainly in the fraction μm . For the most part, the pedogenic kaolinites show poor crystallinity of the fireclay type. They are mainly formed from feldspars and perhaps also amphiboles and pyroxenes in the fractions >2 μm , and from smectites inherited from the calcarenite-residual loam in the coarse (2– 0.2 μm ) and fine clay fractions ( μm ). In one Terra Rossa soil, formation was interrupted twice by deposition of eolian materials, and it is regarded as a polycyclic pedocomplex. Eolian input was much less important during development of the other surface Terrae Rossae. On younger calcarenites ( ⩾100 ka ) near the coast, three Rendzinas (Typic Calcixerolls) show only slight mineral weathering and pedogenic clay formation, in spite of a varied spectrum of primary minerals. In one example, kaolinite formation has just started. The Calcixerolls were probably recalcified by addition of eolian material as a result of anthropogenic thinning of the vegetation and/or due to the vicinity of the coast. These results suggest that, at least in this region, the younger Terrae Rossae of the coastal area were formed over much of the Brunhes epoch. In areas farther from the coast they have been developing for almost all of the Brunhes epoch. Because climatic fluctuations in the Quaternary were generally slight in this region, the direction of soil formation was constant. Therefore we regard the Rhodoxeralfs in the northern part of our study area as Vetusols. According to our expanded definition, Vetusols are surface soils which underwent almost constant processes of soil formation under an almost constant constellation of soil-forming factors, especially climate and vegetation, over a long period of time, including at least some part of the Pleistocene. Consequently the present patchy distribution of Terrae Rossae is hardly a result of climatically induced periods of “geomorphological activity and stability”. but the result of the removal of an earlier dense forest cover, followed by severe soil erosion. The human impact on the ecosystem is much more serious than any climatic fluctuations. In the southwestern part of the study area, between El Jadida and Agadir, the soil moisture regime is dry xeric to aridic and Terrae Rossae occur only in small areas, mostly in depressions. However, two selected Rhodoxeralfs in the vicinity of Tamanar show considerable pedogenic mineral weathering and clay mineral formation, though hardly any kaolinite. The strong weathering and clay illuviation must have been preceded by decalcification, implying a distinctly moister climate here in the past. However, micromorphological features of recent recalcification are common in these Rhodoxeralfs, suggesting that their main properties are not in equilibrium with the present climate and the soils should be regarded as nonburied paleosols or relict paleosols.

Results of earlier studies of Quaternary tephra–paleosol sequences in Central Mexico revealed contradictions between paleopedological and lacustrine records. To settle the contradictions, selected quantitative characteristics of mineral and organic components of the paleosols PT1–PT7 from the Nevado de Toluca sequence were studied as independent paleoclimate proxies. Mineralogical composition of sand and clay fractions allows assessment of weathering and secondary mineral formation, both being climate-dependent processes. Stable carbon isotope ratios of humus and phytolith morphology indicate paleovegetation. In all paleosols, the sand fractions consist mainly of unstable volcanogenic minerals, although the grains have weathering features. Short durations of pedogenesis are responsible for limited weathering status. The clay fraction is dominated by halloysite and dehydrated halloysite in units PT1–PT4, which suggests drier periods during paleosol formation, whereas major amounts of kaolinite in the units PT5–PT7 indicate extended humid pedogenesis. δ 13C values of PT2–PT4 humus are intermediate between those characteristic of C3 and C4 plants. Phytolith assemblages which include both forms of C3 (dominant) and C4 (minor quantities) grasses agree with carbon isotope data. These data indicate plant cover changes driven by wet/dry paleoclimate oscillations. The new results, showing drier stages during the formation of Late Pleistocene paleosols PT2 and PT3, correct the primary interpretation of these units as indicating only humid pedogenesis, and settles the contradiction between paleopedological and lacustrine records.

Two sections (Buenavista and Ahuatenco) of Late Quaternary paleosol-sedimentary sequences of the Glacis de Buenavista, Morelos, Central Mexico, were studied and interpreted as a regional record of climatic change and interaction of pedogenesis and volcanic sedimentation. Buenavista is the deepest section and includes seven pedostratigraphic units, with Andosol (surface unit) and Luvisol (all underlying units) types of pedogenesis. Both types indicate a humid forest environment, the divergency being related to differences in pedogenesis duration. Albeluvisol with a bleached E horizon in unit 5 indicates cooler but still moist conditions in the final Late Pleistocene, whereas strong vertic properties in unit 4 indicate a climate with contrasting seasonal variation of precipitation during the first part of the Holocene. In the upper part of the Ahuatenco section, Bt horizons of different pedogenetic events form a welded Luvisol profile instead of a set of separate paleosols due to less intensive sedimentation. Material of indurated Cm horizons (tepetates) in the lower part of the Ahuatenco section is a mixture of fresh coarse volcanoclastic components and re-deposited Luvisol clayey material, formed by mass movement associated with volcanic events. The resulting granulometric composition of these layers is favourable for structural collapse and hydroconsolidation, which caused hardening together with subsequent pedogenic illuviation and redoximorphic processes.

Buried palaeosols of central Mexico, not previously analysed from a palaeopedological standpoint, have helped to develop a reliable regional model of Late Quaternary climatic change. This paper focuses upon morphological and micromorphological properties, particle-size distribution, and extractable Fe, Al and Si of seven palaeosols (named PT1–PT7) in the vicinity of the Nevado de Toluca volcano. The characteristics of Andic Cambisol PT1, similar to those of modern soils in semi-arid environments, indicate a drier climate in the first half of the Holocene. Humic Andosols PT2–PT4 are analogous to modern volcanic soils of humid forest environments. They show evidence that a moist palaeoclimate prevailed during marine oxygen isotope stages (OIS) 2 and 3. Luvisols PT5 and PT6, which are assumed to have formed at the end of marine OIS 5 to marine OIS 4, also indicate humid conditions. We attribute the differences between Andosols PT2–PT4 and Luvisols PT5–PT7 to variations in the duration in the pedogenesis rather than to changes in palaeoclimate. Micromorphological features of Andosol to Luvisol transition confirm that these soils form an evolutionary sequence. Being for the most part consistent with lacustrine records, the palaeosol properties do not reflect the episodes of ‘drier climate’ during the Last Glacial Maximum, however, as shown by diatom and palynological data from lake sediments. Mesoclimate variations and/or incompleteness of ‘soil memory’, reflecting mostly periods of humid pedogenesis, probably provide the reason for this disagreement. Copyright © 2001 John Wiley & Sons, Ltd.