Downfield Pit, Westmill

Site of Special Scientific Interest · 51.8318, -0.0428

Also within

Hertfordshire County

Condition (Natural England)

Favourable (1) Unfavourable Declining (1)
UnitFeatureConditionArea (ha)Assessed
TL349164 Favourable 0.17 2021-11-20
TL349166 Unfavourable Declining 0.15 2021-11-20

Geology & landscape

Geological Period: Quaternary

Landscape processes: Fluvial, Glacial

Description

Area,3.6 hectares 8.9 ac Description The Westmill area shows a thick and complex sequence of Pleistocene gravels and tills. The sequence at Downfield Pit shows the Westmill Lower Gravel a fluvial deposit of Thames origin overlain by two lithologically distinctive diamicts the Ware and Stortford Tills. These tills are overlain by a thick development of the Westmill Upper Gravel the lower part being dominantly fluvial, the upper being largely fluvioglacial. Elsewhere in the region, this gravel is succeeded by a further till, the Westmill Till. This sequence is important for establishing the pre-diversion course of the Thames, the nature of the post diversion Lea deposits and their relationship to the complex Anglian glaciations of the region. Downfield Pit, Westmill is a key site linking two classic areas of Middle Pleistocene stratigraphy the middle Thames region and East Anglia.