The Aquitanian is, in the ICS' geologic timescale, the oldest age or lowest stage in the Miocene. It spans the time between 23.03 ± 0.05 Ma and 20.43 ± 0.05 Ma (million years ago) during the Early Miocene. It is a dry, cooling period. The Aquitanian succeeds the Chattian (the youngest age of the Oligocene) and precedes the Burdigalian.
The Aquitanian age overlaps with the Harrisonian, Agenian, Pareora, Landon, Otaian, and Waitakian ages from various regional timescales.
Aquitanian (stage) Wikipedia
The Aquitanian stage was named after the region Aquitaine in France and was introduced in scientific literature by Swiss stratigrapher Karl Mayer-Eymar in 1858.
The base of the Aquitanian (also the base of the Miocene series and the Neogene system) is defined as the place in the stratigraphic column at the first appearance of foram species Paragloborotalia kugleri, the extinction of calcareous nannoplankton species Reticulofenestra bisecta (which forms the base of nannoplankton biozone NN1), and the base of magnetic chronozone C6Cn.2n. The official GSSP for the Aquitanian stage lies in the Lemme-Carrosio section near the small village of Carrosio (north of Genoa) in northern Italy.
The top of the Aquitanian stage (the base of the Burdigalian) is at the first appearance of foram species Globigerinoides altiaperturus and the top of magnetic chronozone C6An.