Volcanic ash layers were penetrated in three of the sediment cores recovered during 1965 off Florida as part of the JOIDES deep drilling program. The ash in these cores consists of shards of fresh acidic glass with a size distribution centered in the 30-60-micron fraction. In all samples, the ash is in Oligocene strata, as indicated by planktonic Foraminifera such as Chiloguembelina cubensis, Globoanomalina micra, Globorotalia postcretacea, and G. yeguaensis. Such a fauna is typical of the Vicksburg Group of the United States, and other Oligocene sections in Europe and Africa. Potassium-argon dates of the ashes provide absolute ages for the Oligocene. These JOIDES ash layers appear not to be correlative with ash beds found in the Tertiary Oceanic Formation of Barbados.