The Quaternary period began with the Pleistocene stage approximately 1.64 million years ago. This stage is represented by superficial deposits of sand, mud/clay and particularly terraced gravels, which were the by-product of water erosion and changes in sea level during the various interglacial episodes at this time. The Holocene (or post-glacial) stage began 0.01 million years ago and still continues.
Quaternary deposits have been recorded throughout the county, along the coast and on the seabed, both as continuous features and in isolated pockets.
Derived flint casts
The Quaternary gravels contain derived sandstone blocks, flint casts of fossils eroded from the Cretaceous, worked flint tools and pseudo-fossil bone. The Quaternary clays deposited during this period are present offshore and are occasionally seen on the Solent coast. These clays provide important data on history of the Solent and include mammal teeth and bones, mollusc shells and poorly preserved plant remains.
Fossil preservation from the Pleistocene stage varies considerably. Unweathered clay tends to produce good quality specimens, but the high levels of acidity found in the sands and gravels can destroy all but the most robust of specimens.
Quaternary gravels capping the Paleogene, Brownwich, Hampshire
Vertebrate remains are not common in the Quaternary sediments of Hampshire. Marine vertebrate faunas are rare but when present are represented by fossil fish remains. Fossil mammals dominate the terrestrial vertebrate fauna.
Invertebrates remains are common in the Quaternary sediments of Hampshire. Fossil mollusc remains, particularly bivalves and gastropods, dominate the marine faunas. Terrestrial invertebrate faunas are poorly represented in the collection.