Some coastal soils in Namaqualand have significant amounts of sepiolite. Palygorskite is relatively low in coastal soils but it is abundant at some inland sites up to 600 km from the coast. This distribution is explained by examining relationships of major ionic species in saturated paste extracts. Our study found two categories of geographically and chemically distinct palygorskite-containing soils: 1) high Mg, palygorskite soils 130 km inland with similar Mg levels to coastal sepiolitic soils, and 2) low Mg, palygorskite soils 600 km inland. The geographic progression from high-Mg sepiolite-containing soils at the coast, through high-Mg palygorskite soils to low-Mg palygorskite soils farthest from the coast parallels the chemical variation in the sepiolite-palygorskite continuum from sepiolite, the most magnesic endmember at the coast, to palygorskite the least magnesic endmember farthest inland. MgSO40 and MgCl+ ion complexes do not appear to depress Mg2+ activity to an extent that is able to distinguish sepiolite-containing from palygorskite-containing soils. Calcite in the profile is strongly associated with occurrence of fibrous clay minerals, and dolomite is absent. Compositions of soil saturated paste extracts conform to their respective mineral stability fields, contrasting with previous work in the area. The previous interpretation, therefore, that fibrous minerals may currently be in a state of alteration requires revision. Evaporation of soil pore waters in the marine-influenced region results in increased Mg and Ca and decreased pH, even with precipitation of sepiolite and calcite. These chemical changes with evaporation are important for understanding the evolution of soil solutions and precipitating minerals in arid coastal environments and the chemistry of waterbodies associated with them.