Paleosol identification is simplified by considering soil as a natural body withinternal organization and a history of formation. This definition assumes that we accept paleosolsas soils. In a paleosol classification,...Paleosol identification is simplified by considering soil as a natural body withinternal organization and a history of formation. This definition assumes that we accept paleosolsas soils. In a paleosol classification, inclusion of the cold region paleosols at the suborder levelplaces temperature (climate) in balance with the other soil forming factors. Because ancienttemperatures were not recorded, we use soil and parent material properties as proxies to identifyancient soils from Arctic and Subarctic regions. The properties include permafrost andcryoturbation features as well as those resulting from glacial processes. These features generallypersist through later cycles of soil formation as climate has changed. Examples both within andbeyond the glacial borders in Wyoming, Illinois, and Indiana, USA are presented and classifiedusing an arctic paleosol suborder modifier, the formative element.展开更多
Thirty-nine soils were studied on Holocene and late Pleistocene geomorphic surfaces.Granodiorite, sandstone, and alluvium derived from these rocks are the parent materials. Climateis Mediterranean. Chamise （Adenostom...Thirty-nine soils were studied on Holocene and late Pleistocene geomorphic surfaces.Granodiorite, sandstone, and alluvium derived from these rocks are the parent materials. Climateis Mediterranean. Chamise （Adenostoma faciculatum） is on the drier sites and redwood （Sequoiasempervirens） on the moister sites. Our objectives are twofold, （1） Find if today’s two-season wet-dry, subhumid climate explains the general noncalcic nature of the soils, or if not （2） accept thattheir noncalcic nature results from more moist past climates and define some indicator soilproperties. The depth to carbonate in the soils formed in calcareous materials on Holocenesurfaces corresponds roughly to the average annual depth of water movement, not to the predictedwettest years. We accept then, that the relict paleosols formed under one or more pluvial cyclesbecause they are free of carbonate below their B horizons. Defined levels of pedon clayaccumulation, dithionite-citrate extractable Fe （Fe<sub>d</sub>） accumulation in the B horizons, cationexchange capacity at pH 7 （CEC<sub>7</sub>） to clay ratios, and the minimum base saturation at pH 7 （BS<sub>7</sub>） inthe pedons are useful properties for separating these relict paleosols from the Holocene age soils.A further evidence of the relict nature of the soils on the Pleistocene surfaces is the weatheringreversal noted in these previously weathered materials.展开更多
文摘Paleosol identification is simplified by considering soil as a natural body withinternal organization and a history of formation. This definition assumes that we accept paleosolsas soils. In a paleosol classification, inclusion of the cold region paleosols at the suborder levelplaces temperature (climate) in balance with the other soil forming factors. Because ancienttemperatures were not recorded, we use soil and parent material properties as proxies to identifyancient soils from Arctic and Subarctic regions. The properties include permafrost andcryoturbation features as well as those resulting from glacial processes. These features generallypersist through later cycles of soil formation as climate has changed. Examples both within andbeyond the glacial borders in Wyoming, Illinois, and Indiana, USA are presented and classifiedusing an arctic paleosol suborder modifier, the formative element.
文摘Thirty-nine soils were studied on Holocene and late Pleistocene geomorphic surfaces.Granodiorite, sandstone, and alluvium derived from these rocks are the parent materials. Climateis Mediterranean. Chamise （Adenostoma faciculatum） is on the drier sites and redwood （Sequoiasempervirens） on the moister sites. Our objectives are twofold, （1） Find if today’s two-season wet-dry, subhumid climate explains the general noncalcic nature of the soils, or if not （2） accept thattheir noncalcic nature results from more moist past climates and define some indicator soilproperties. The depth to carbonate in the soils formed in calcareous materials on Holocenesurfaces corresponds roughly to the average annual depth of water movement, not to the predictedwettest years. We accept then, that the relict paleosols formed under one or more pluvial cyclesbecause they are free of carbonate below their B horizons. Defined levels of pedon clayaccumulation, dithionite-citrate extractable Fe （Fe<sub>d</sub>） accumulation in the B horizons, cationexchange capacity at pH 7 （CEC<sub>7</sub>） to clay ratios, and the minimum base saturation at pH 7 （BS<sub>7</sub>） inthe pedons are useful properties for separating these relict paleosols from the Holocene age soils.A further evidence of the relict nature of the soils on the Pleistocene surfaces is the weatheringreversal noted in these previously weathered materials.
