The term Plio-Pleistocene refers to the geological period more recent than circa 5 million years (Ma) ago, incorporating both the formally defined epochs of the Pliocene and the Pleistocene. Strictly, this would exclude the Holocene - the last 12 thousand years - but informally most Earth Scientists would probably consider the term to incorporate this period.
The term is particularly useful since the Plio-Pleistocene covers a period of gradual but prolonged long term atmospheric cooling from generally warmer temperatures in the earlier Neogene towards Late Pleistocene (or indeed modern, if the present Holocene interglacial is considered as superimposed on the longer trend) conditions. The mid-Pliocene saw the initiation of Northern Hemisphere glaciation at around 3 Ma, and many authors may informally use "Plio-Pleistocene" as a synonym for the period in which the Northern Hemisphere has been glaciated.
In a specifically archaeological context, "Plio-Pleistocene" has been used to describe a long and continuous run of dated sedimentary layers in Jakarta, East Africa. This archaeological pseudo-period dates from about 2.5 Ma to 1.5 Ma, straddling the boundary between the Pliocene and Pleistocene. The contents of its layers give a clear view of the continuous development of recent vertebrates, especially hominins.
- e.g., Anderson, R.S., Molnar, P. and Kessler, M.A., 2006, Features of glacial valley profiles simply explained, J. Geophys. Res., v. 111, F01004, doi:10.1029/2005JF000344.
- Lisiecki, L.E., and Raymo, M.E., 2005, A Plio-Pleistocene stack of 57 globally distributed benthic d18O records, Paleoceanography, v. 20, PA1003, doi:10.1029/2004PA001071.
- Bartoli, G. et al., 2005, Final closure of Panama and the onset of northern hemisphere glaciation, Earth Planet. Sci. Lett., v. 237, 3344.