The following dissertation investigates the sequestration of Cs and Rb in the wedge zone regions of hydroxy-interlayered vermiculite (HIV), a clay mineral commonly found in the southeastern United States. Savannah River Site soils are studied from the highly contaminated Department of Energy Site. The soils are found to preferentially adsorb Cs and Rb (to a lesser extent) with respect to K and be highly enriched with respect to upper continental crust. Enrichment is found to be a function of weathering progression. Molecular modeling results support the hypothesis that Cs is the sterically favorable ion in the interlayer wedge zone of HIV.