BASAL MIXING ZONES IN LOESSES OF LOUISIANA AND IDAHO .2. FORMATION, SPATIAL-DISTRIBUTION, AND STRATIGRAPHIC IMPLICATIONS

Basal mixing zones of loess with different underlying materials in Louisiana and Idaho have been identified. Formation of basal mixed zones occurs when loess is deposited on a pedogenically active surface and becomes incorporated into the underlying stratigraphic unit through bioturbation and pedoturbation processes. Factors influencing basal mixed zone formation include climate, nature of stratigraphic materials underlying the loess deposits, and rate of loess deposition. The warm, humid climate in Louisiana is more conductive to the formation of thicker basal mixed zones than the cool, semiarid climate of Idaho. In Louisiana, thicker basal mixing zones were found where loess was underlain by coarse textured, unconsolidated materials than where underlain by unconsolidated materials with similar or finer textures.