a name given by many geologists to the rock layer whose base defines the beginning of the Pleistocene Epoch, approximately 1.8 million years ago. As defined in 1985, the global stratotype section and point (GSSP) for its lower boundary is the base of clay stones in a sequence of marine strata about 4 km (2.5 miles) south of Crotone on the Marchesato Peninsula of Calabria, Italy. The upper boundary of the Calabrian Stage has not been agreed upon universally. Some geologists have considered the Calabrian to encompass all rocks laid down during the entire Pleistocene, which was succeeded by the Holocene Epoch approximately 11,800 years ago. Other geologists consider the Calabrian to be an alternate name for the Lower Pleistocene Stage, which is overlain by the Middle Pleistocene Stage at a boundary laid down some 780,000 years ago. In neither case has a GSSP been agreed upon for the upper boundary of the Calabrian Stage.