• The Reading and Thanet Beds are the earliest rocks of the Tertiary epoch in this region. They outcrop in Essex, Hertfordshire and south-east Suffolk. Tough sarsen stones and puddingstones found in these areas are thought to have originated from a now-vanished layer of the Reading Beds.

A sarsen stone extracted from the bed of the River Orwell in the 19th century; now on display at Christchurch Park, Ipswich.		Seen here at Ballingdon Pit, Suffolk, the Bullhead Bed features glauconite-coated flints at the base of the Thanet Beds. It is a lag deposit left by the scouring action of the Palaeocene sea over the Chalk seabed.

Eocene

• The London Clay is a blue-grey rock which underlies much of Essex and parts of Hertfordshire. It was laid down in a tropical sea and may contain fossil plant remains and sharks’ teeth. It has been much used for brick making, and its nodular layers (septaria) have been burned to make cement.

London Clay cliffs at Nacton Shore, Suffolk. The grey bands include volcanic ash thought to have been erupted from volcanoes in Germany.		A specimen of London Clay rock showing mud cracks over 45 million years old.

Pliocene

• The Crags are a sequence of sandy, marine deposits laid down in the gradually cooling climatic conditions leading up the ‘Ice Age’. They outcrop in the eastern parts of Suffolk and Norfolk. The Coralline Crag is the oldest layer, a limestone which is only found in Suffolk. The Red Crag and Norwich Crag may include the remains of fossil mammals such as mastodon, sabre-tooth and whale.

Norwich Crag gravels of the Westleton Beds exposed in the cliffs at Dunwich heath, Suffolk.		Fossil shells from the Red Crag at Buckanay Pit, Suffolk, deposited in a current bedded structure.

Pleistocene

• The Pleistocene ‘Ice Age’ is a complex series of cold glacial and warm interglacial climatic periods. It has left an important legacy of ‘drift’ or superficial deposits across the region. Many classic geological sites for understanding the Pleistocene are found in the region.

  During the early Pleistocene the ancestral River Thames flowed diagonally across the south-eastern part of the region, depositing a sequence of river terrace deposits known as Kesgrave Sands and Gravels. The coldest period, the Anglian, saw ice sheets spreading as far south as St Albans, diverting the early Thames southwards and scooping out the broad depression that is now the Fens. It left behind boulder clay and sandy outwash deposits that mantle many parts of the region’s landscape, and which underlie much of the best corn-growing farmland in East Anglia. During cold periods the landscape was also shaped by periglacial freeze-thaw action which mobilized soil layers and shaped the Chalk escarpment and other slopes, while rivers deposited thick sand and gravel sequences in valleys such as the Great Ouse, Lea and Wensum, so providing valuable resources for the aggregate industry. Plants and animals, including humans, were able to colonise the region during warmer interglacial periods. Pakefield in Suffolk has produced evidence of the earliest humans in northern Europe, dating back 680,000 years.
   

  Evidence of glacial conditions about 450,000 years BP: an ice wedge cast at West Runton, Norfolk, showing where a wedge of ice filled a crack in underlying sands and gravels.		Trimingham Cliffs, Norfolk are formed from the moraine of a Pleistocene ice sheet. Blocks of dolerite transported here from northern England by ice action are resting on the beach.

  A scene in the Stour Valley during a warm interglacial period, c.200,000 years ago, reconstructed from geological evidence, including plant and animal fossils and flint tools. The landscape is a wide grassy valley with patches of woodland. Herds of mammoth, bison and wild horse crop the grassland, while forest-dwelling animals browse in the woods. Meanwhile a pack of hyaenas are ready to defend a red deer carcase from a band of Neanderthal hunters. Freshwater clam shells lie on the riverbank, alongside discarded flint tools. This scene is taken from the Suffolk Mammoth Trail panel at Holbrook Bay. Artwork © Beverly Curl.

  A scene in the Waveney valley during a cold glacial period 60,000 years ago, reconstructed from geological evidence, including plant and animal fossils. The landscape is herb-rich steppe grassland with a few scattered trees. Woolly mammoth and woolly rhinoceros are browsing dwarf willow and birch bushes, while a herd of horses views a pack of wolves uneasily. A herd of reindeer are on their way to higher ground to avoid swarms of biting insects. This scene is taken from the Suffolk Mammoth Trail panel at Homersfield. Artwork © Beverly Curl.

Holocene

• The last 10,000 years are part of the Holocene, which is the name of the present interglacial period. Human life has spread throughout the region, modifying and shaping the landscape in new ways through settlement, farming and other activities. Meanwhile geological deposits continue to form under active geomorphological processes, particularly in coastal areas and river valleys. These deposits include dunes, shingle banks and sandbanks, estuarine salt-marshes and mudflats, and layers of peat and alluvium. Notable tracts of peaty land have formed in the Fens and other low-lying areas like the Norfolk Broads. Thus rocks continue to be laid down for the future.

Long-shore drift operates strongly around the East Anglian coast, transporting and depositing shingle in offshore banks and beaches, as seen here at Thorpeness, Suffolk.		Four hundred years ago, the Fenland was a wetland wilderness of fens, rivers, meres and carr woodland. Today it has deep fertile soils, developed from thick layers of peat and alluvium built up since the last Ice Age, as seen here at Wangford Fen, Suffolk.