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The paleopedological record is, essentially, the fossil record of soils. The paleopedological record consists chiefly of paleosols buried by flood sediments, or preserved at geological unconformities, especially plateau escarpments or sides of river valleys. Other fossil soils occur in areas where volcanic activity has covered the ancient soils. ==Problems of recognition== After burial, soil fossils tend to be altered by various chemical and physical processes. These include: * Decomposition of organic matter that was once present in the old soil. This hinders the recognition of vegetation that was in the soil when it was present. * Oxidation of iron from Fe2+ to Fe3+ by O2 as the former soil becomes dry and more oxygen enters the soil. * Drying out of hydrous ferric oxides to anhydrous oxides - again due to the presence of more available O2 in the dry environment. The keys to recognising fossils of various soils include: * Tubular structures that branch and thin irregularly downward or show the anatomy of fossilised root traces * Gradational alteration down from a sharp lithological contact like that between land surface and soil horizons * Complex patterns of cracks and mineral replacements like those of soil clods (''peds'') and planar ''cutans''. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Paleopedological record」の詳細全文を読む スポンサード リンク
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