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Existance, formation and effects of hardpans were studied in soils of Rudasht region in Isfahan . By determining the similarity indices, lithologic discontinuity was surveyed in these soils. In the sites with the same depth of hardpan and lithologic discontinuity , the origin of hardpans was related to river sedimentation , while in other locations ,it was related to pedogenesis (soil and water interactions ).
Topography of the hardpans was effective on direction of lateral drainage flow and caused water- logging in some locations. Hardpans, with depths of more than 190-280 cm from soil surface, caused soil salinization , alkalinization , and as a result, low crop production. In the study region, it was shown that low terraces of the river were with lothologic discontinuity (resedimentation) and high terraces of the river were without lithologic discontinuity. From the slope of lithologic discontinuity, wich was toward the river, it was concluded that the location of the river has not been changed (since the latest lithologic discontinuity).