A division of the Quaternary System defined by its deposits. It is a worldwide division of rocks deposited during the Pleistocene Epoch (1,600,000-10,000 years ago). It overlies rocks from the Pliocene Epoch (5.3-1.6 million years ago) and is itself overlain by rocks of the Holocene Series; together these two latter divisions make up the Quaternary System. These deposits contain evidence of humans and their development throughout glacial and interglacial conditions. . By international agreement, the global stratotype section/point for the base of the Pleistocene Series is in the Vrica section in Calabria, Italy. The Pleistocene's boundary with the Pliocene occurs just above the position of the magnetic reversal that marks the Olduvai Normal Polarity Subzone, thus allowing the worldwide correlation of Pleistocene rocks with reference to the magneto-stratigraphic timescale.