نتایج جستجو برای: developed horizons
تعداد نتایج: 772676 فیلتر نتایج به سال:
Four new AMS 14C ages, glacial mapping, and measurements of soil development, loess thickness, and moraine morphology constrain the age and extent of at least three Quaternary advances by outlet lobes of an ice cap over the Ahklun Mountains of southwestern Alaska. The relative-age data are from 107 sites correlated to 25 ice-marginal positions in the Kanektok, Goodnews, Togiak, and Kulukak Rive...
Field and laboratory analyses of soils on 11 well-dated fluvisil terraces spanning the past 0.5 m.y. demonstrate that a threshold governs changes in several morphological and chemical characteristics of increasingly older soils. Correlations with respect to time among iron species, soil morphology, and soil silt and clay demonstrate that the chronosequence at Cajon Pass reflects primarily an ev...
Clay mineralogy of paleosols provides more information about Quaternary climatic changes and paleoenvironmental conditions. Clay minerals of an alluvial fan in eastern Isfahan were studied, using x-ray diffraction analysis. Studied paleosols are located on old Qf1 and Qf2 geomorphic surfaces. Qf1 geomorphic surface is older and topographically higher than Qf2. The results of clay mineralogy sho...
Field and laboratory data combined with geochronological information were used to investigate the nature and rates of pedogenesis of three late Holocene soils at the Lubbock Lake archaeological site (Southern High Plains of Texas). A variety of pedologic characteristics become better expressed with time, and aerosolic additions and burial of the soils significantly affect the development of the...
Within the percolation and soaked facies of the Greenland ice sheet, the relationship between radar-derived internal reflection horizons and the layered structure of the firn column is unclear. We conducted two small-scale ground-penetrating radar (GPR) surveys in conjunction with 10m firn cores that we collected within the percolation and soaked facies of the Greenland ice sheet. The two surve...
Turbic Cryosols (permafrost soils characterized by cryoturbation, i.e., by mixing of soil layers due to freezing and thawing) are widespread across the Arctic, and contain large amounts of poorly decomposed organic material buried in the subsoil. This cryoturbated organic matter exhibits retarded decomposition compared to organic material in the topsoil. Since soil organic matter (SOM) decompos...
Techniques for conventional forest soil surveys in Taiwan need to be further developed in order to save time and money. Although some soil-landscape regression models have been developed to describe and predict soil properties and depths, they have seldom been studied in Taiwan. This study establishes linear soil-landscape regression models related to soil depths and landscape factors found in ...
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Particles were isolated from soil leachates from the genetic horizons of a subalpine Podzol from the central Cascades, Washington. Organic particles containing traces of aluminum, iron, silicon, and sulfur were predominant in the migrant material through the upper horizons (horizons A + B); their movement was arrested in the B2hir horizon. Below B2hir and at depth, phyllosilicates, quartz, and ...
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