Lake Torrens, a normally - dry salina whose surface is 112 feet above sea level, has been the site of accummulation of some l,000 feet of continental lacustrine sediments since Eocene times. Sublake sediments encountered in boring comprise in ascending order, Eocene carbonaceous mudstones, sands and siltstones, a ?Miocene dolomite-mudstone sequence, and Quaternary red-brown siltstones, clays, gypsum, sands and muds. The lake has been the focus of an internal drainage system obviously for only limited periods during its existence. The sea has not had access to this portion of the graben since the foundering of the Spencer-Vincent-Torrens rift system. The brines enclosed by the sublake sediments are chloride waters without useful concentrations of salts other than sodium chloride.