(24 - 1.8 million years ago)
No rocks of this age are known to be preserved within Fforest Fawr Geopark. In common with most of Britain (but not parts of south and east England) the area lay above sea level during most of this period and is believed to have enjoyed a semi-tropical climate. The Antarctic ice-sheet began to develop early during the Neogene.
Far to the west the modern Atlantic Ocean continued to widen and far to the south the Alps were being raised. In Wales, as over much of western Britain, the rocks were lifted up perhaps as much as 1000 metres so that what remains after subsequent erosion forms the present high hills.
The nearest exposures on land of rocks of this age are to be found in Cornwall, Kent and Suffolk.
The Neogene together with the Palaeogene period which precedes it are the new names for what we used to call the Tertiary Period.
The name 'Neogene' derives from the Latin for 'new formation' - the later part of the former Tertiary period.
'Tertiary' belongs to a time in the history of the science when geological time was divided into four great 'orders': the Primary, Secondary, Tertiary and Quaternary. We no longer use the first two terms but 'Tertiary' and 'Quaternary' are still commonly used.
Some geologists also include the Quaternary period (which continues to the present day) as a part of the Neogene.