Dish-shaped lenses of dolomitic limestone commonly occur in the arenaceous Lower Tertiary and Quaternary eolianites of the Central Namib Desert region. They are interpreted as the deposits of vegetated playa lakes and, as such, have been described as "fossil oases." Regional stratigraphic studies have shown that there were two separate wet episodes during which these playa lakes formed. These are the Zebra Pan Carbonates of the Late Eocene-Early Miocene Tsondab Sandstone Formation and the Khommabes Carbonates in the partially consolidated Late Pliocene-Recent Sossus Sand Formation. In plan view, the dolomitic limestone beds have a roughly concentric distribution of lithofacies and trace fossils that reflect the water-table depth and the interaction of the vegetated lake margins with the surrounding dunes.