Pleistocene deposits were excavated in 2016 at Former HM Prison, Canterbury.
Analysis of the geological sequence suggested that deposits were cut into by a side valley, thought to be related to a spring (either subterranean or extinct). The first deposit in the base of the valley comprised clay with chalk clasts; this either formed as a coombe deposit brought in by fluvial/colluvial activity, or through freeze-thawing of ground water. This deposit is indicative of a cold and occasionally wet environment, and the valley itself if suggested to be contemporary with the First Terrace associated with the Stour - between 25,000-400,000 years BP (before present).
This layer was overlain by clayey sand with flints, indicative of high energy head deposition in the side valley.
These layers were overlain by a series of clays indicative of lower energy head or alluvial deposition.
The clays were overlain in one area by finer grained brickearth clays, suggesting that they were windblown in origin. They are likely to date to the Last Glacial Maximum around 22,000 yrs BP.
Overlying this sequence were deposits of heavy, gravelly clays thought to represent head deposits which formed during a rapid warming period interrupted by three cooler periods, ending the Pleistocene and beginning the Holocene around 12,000yrs BP
No finds were recovered.(1)

<1> Canterbury Archaeological Trust Ltd, 2016, Former HM Prison, Longport, Canterbury Archaeological watching brief on geotechnical work (Unpublished document). SKE52667.