Geology Site Account

Gravel pit yielding Palaeolithic artifacts and fossils from interglacial sediments. Further excavations could yield further artifacts and fossils.

-----------------------------------------------------------------

Site description

The working gravel pits at Barling are excavating the Barling Gravel, an extensive spread of gravel and sand laid down by the Thames-Medway river when it was a large, braided river flowing north across this part of Essex. It is about 250,000 years old and dates from Marine Isotope Stage 8 (MIS 8) and equivalent to the Lynch Hill/Corbets Tey terrace of the Thames. The Barling Gravel is part of the Low Level East Essex Gravel and forms the lowest tread in this staircase of terrace deposits fringing the Essex coast. Fossils found in the gravel have included the bones of elephant, mammoth, horse, aurochs, bison, red deer, giant deer and possibly rhinoceros, which may represent one of the few MIS 8 assemblages known in Britain.

However, of most interest and importance was the discovery, in January 1983, of interglacial sediments rich in animal and plant fossils in the floor of a gravel pit at Barling (Bridgland et al. 2001). These deposits filled a channel cut into London Clay bedrock and overlain by the Barling Gravel. The channel sediments yielded molluscs and plant remains that imply that they were deposited in fully interglacial conditions. Fossil pollen in the sediments has shown that they accumulated during the early part of an interglacial. Remains of beetles, including dung beetles, were also found, which enabled geologists to make a reliable estimate of the temperature of the interglacial. Different beetle species are known to occupy particular ecological niches and are therefore a good indicator of palaeoclimate. The remains of verte-brates have also been recovered from the interglacial deposits. All this evidence, in a single channel deposit, has enabled geologists to reconstruct the river environment, and the nature of the surrounding woodland and meadows, that was in existence in this part of Essex during this warm period of the Ice Age.

The age of the interglacial deposits is not known but evidence from the molluscs, and its connection with the overlying Barling Gravel, supports an age of about 300,000 years (MIS 9).

The presence of humans on the banks of the Thames-Medway river at this time is indicated by the discovery of numerous Palaeolithic flint implements including at least 10 hand-axes. One of the hand-axes, discovered in 1960, is a particularly fine example and is on display in Southend Museum. It is an elegant 25 centimetre (10 inch) long pointed hand-axe, stained brown and in sharp condition.

In the Barling area the fields sometimes reveal crop marks which are a reminder of a time when Essex was had an extremely cold climate. During the coldest part of the most recent glaciation, about 25,000 years ago, an ice sheet extended as far south as Norfolk and the extremely cold temperatures throughout Essex have left their mark on the landscape. Known as periglacial features they include ice-wedge polygons which are formed when the ground shrinks and cracks creating a network of ice wedges not unlike the much smaller scale pat-tern of cracks that often appears on the dried mud on the edge of a lake. Each summer, these giant cracks filled with water which later froze widening the cracks; a process which continued throughout the glacial stage. At the end of the glaciation, 10,000 years ago, these cracks filled with debris preserving them as ice-wedge casts which are sometimes revealed as crop marks in the fields during hot, dry summers. Some years ago, a remarkable network of fossil ice-wedge polygons were revealed in the Barling Hall Pit.

-----------------------------------------------------------------

Barling Gravel Pit works the Barling Gravel, a cold climate deposit laid down by the Thames-Medway River about 250,000 years ago. Overlying this gravel is about 3 metres of calcareous brickearth or loess. The floor of the pit is London Clay bedrock. Photo © Francis Wenban-Smith, Department of Archaeology, University of Southampton