1,721,210 research outputs found
The potential of combining of lacustrine, palaeopedological and other palaeo-environmental archives – general idea and examples from the Late Pleistocene in the Mediterranean
No full textGenese, Verbreitung und Eigenschaften periglaziärer Lagen im Rheinischen Schiefergebirge - anhand von Beispielen aus Westerwald, Hunsrück und Eifel
No full text
Genese, Verbreitung und Eigenschaften periglaziärer Lagen im Rheinischen Schiefergebirge - anhand von Beispielen aus Westerwald, Hunsrück und Eifel
No full text
Approaches to quantify progressive soil development with time in Mediterranean climate—I. Use of field criteria
No full textSoil‐chronosequence studies are useful to assess relationships between land‐surface ages and stages of soil formation. Such relationships may then be applied to establish relative chronologies of development of land surfaces of unknown ages, contributing to landscape‐history reconstruction. For this purpose, it is important to identify those soil properties that are most closely related to soil age. This article reviews soil‐chronosequence studies from Mediterranean regions in Europe and California. Soil properties described in the field and soil‐development indices based on field criteria that have been used in the studies are evaluated. The properties total texture, rubification, clay films, dry consistence, and soil thickness are identified as useful and easy‐to‐obtain soil parameters, which are generally closely related to soil age. Most soil properties exhibit their greatest changes during certain phases of soil development, e.g., soil structure in soils 100,000 y. The specific time spans of major changes of soil properties need to be considered, when looking for appropriate parameters to study a particular chronosequence. Indices, which combine several soil properties having their greatest changes in different phases of soil development, are useful to study soil chronosequences comprising large time spans, e.g., from Holocene to Middle Pleistocene. It is important to be aware that soil chronofunctions obtained from Pleistocene soils integrate rates of soil‐forming processes over periods of very variable climate and environment, and that soil development crossed internal and external pedogenic thresholds that are not reflected in soil chronofunctions
Soil Development: Numerical Indices
No full textNumerical indices of soil development provide highly useful tools for comparing soil profiles or soil horizons in terms of the degree of pedogenesis that has taken place in them. In this way, numerical indices may also help to establish chronologies of the age of different land surfaces. Common indices used in soil sciences, and the pedogenic processes associated with them, comprise the theme of this entry. Indices based on field data include the redness rating and the profile development index, or PDI. Clay formation can be evaluated by the clay accumulation index (CAI), and pedogenic iron oxides by ratios of iron fractions. Various ratios of mobile versus immobile elements are used as indices that reflect silicate weathering and leaching of released mobile elements. Indices of profile anisotropy are based on the concept that pedogenesis increases anisotropy in soils over time. Some indices reflecting specific processes (carbonate accumulation and podzolization) are also described. Appropriate use of any soil development index requires that the soil-forming processes which the index was designed to reflect match with the processes that take place in the soils under investigation. Hence, knowledge on both the concepts of the indices and the processes taking place in the soils is needed, including variations in soil-forming processes in both space and time (especially over time spans that include major climatic shifts)
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