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Geology of the Lower Trent Valley

The East Trent villages downstream from Newark are situated in the broad alluvial flood plain of the River Trent.
 

The “drift” or “upper” geology of this area consists of sand, gravel and silt which has been deposited since the ends of the last ice-ages which are ascribed to the Quaternary Period of earth history. The Quaternary is divided into two Epochs or sections, the Pleistocene starting some two million years ago and the Holocene lasting from around 10000 years ago to the present day. Over this period, huge ice sheets up to a mile thick covered most of north west Europe with temperate or warm periods intervening. These resulted in repeated extensions and retreats of the ice in what are referred to as inter-glacial periods in which the latter Epoch saw the sculpturing of the land surface to its present state.

During the inter-glacial periods, the warming climate lead to significant ice decay and the rise or rebound of land surfaces in response to the reduction in the considerable weight of the overlying ice. This melting ice released massive volumes of water with huge energy allowing it to carry rocks and gravels over considerable distances down the river valley.

As the rise in land surface slowed the river became less vigorous and unable to support coarse sediment loads. Meanders and remnant pools began to form in the river valley and deposition became confined to fine sediments, silts and clays which form the alluvium covering the valley floor today. Subsequently, the Trent referred to by the Anglo-Saxons as “wild, uncontrollable and unpredictable”, became confined to a single channel over the centuries by the hand of man.

The composition of the gravels shows them to consist predominantly of quartzite pebbles from the Triassic period (225 to 190 million years ago) which forms much of the bedrock further upstream plus minor amounts of flint, limestone and sandstone. Also present are other materials which have been introduced by the river – partly fossilised bog oak, lignite and finer woody debris.

The deposits also yield deer, hippopotamus and mammoth bones and teeth which have been used to date the gravels to between 40,000 and 10,000 years ago. 

Andrew Hindmarsh
Nottinghamshire Wildlife Trust

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