Great Blakenham Pit

Site of Special Scientific Interest · 52.1062, 1.0899

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Also within

Suffolk County

Condition (Natural England)

Favourable (2) Unfavourable Declining (1)
UnitFeatureConditionArea (ha)Assessed
TM103505 — Favourable 0.23 2021-11-15
TM108503 — Favourable 0.04 2021-11-15
TM116498 — Unfavourable Declining 1.96 2022-03-30

Climate exposure

This is about exposure to a nationwide pressure this habitat type carries — not a verdict on this site's own management.

Coastal

Coastal habitats are exposed to sea-level rise and storm erosion. Where hard sea defences sit behind them, there's nowhere landward to retreat to — a squeeze that keeps compressing the habitat no matter how well it's managed.

Habitats

Fast flowing river and stream

Geology & landscape

Mining / Industrial: Quarry · Geological Period: Quaternary · Rock Type: Glacial Till

Landscape processes: Coastal, Glacial, Periglacial

Description

Description The great Blakenham site exposes a sequence through Early and Middle Pleistocene sediments and soils. These include residual Crag, a thick body of estuarine sands, a thin layer of Thames river gravels, a buried soil complex, an extensive glacial till and associated outwash gravels. The present top soil developed on the till includes periglacial soil structures and lenses of wind blown sand. All these deposits make the site of great importance in interpreting the glacial history of southern Britain in Middle Pleistocene times. The Thames river deposits are part of a terrace sequence which represents the former course of the Thames through East Anglia. The buried soil shows a bright red colour caused by redeposited hematite, resulting from temperate weathering during several stages of the Middle Pleistocene, in addition to a periglacial soil formed in the early part of the Anglian Glaciation but before the Anglian glaciers reached the site. Formerly, the till was considered to be evidence for two separate glacial stages, but recent analysis show that differences in appearance are due to the upper part being oxidised and the sediment is now considered to represent only one glacial event, of Anglian age, but within the till three facies are represented. In the western part of the quarry there is lodgement till; to the east, on the valley side, melt out till overlies a sheared basal till. In this part of the quarry the till is associated with chalky ice proximal outwash gravels. The quarry is very important for showing the spatial relationship of the till facies and the topographic position of the outwash gravels. The wind blown sands in the top soil are Devensian. This is a key locality for Pleistocene studies.

Plant communities

A9 — Fast flowing river and stream, Marginal and inundation, Pond ditch and canal, Sluggish river and stream

Potamogeton natans community

Schoenoplectus lacustris, Juncus bulbosus, Sparganium angustifolium, Sparganium erectum, Sparganium minimum, Alisma plantago-aquatica, Lobelia dortmanna, Equisetum fluviatile, Myriophyllum alterniflorum, Elodea canadensis, Lemna minor, Lemna trisulca, Nymphaea alba, Callitriche platycarpa, Callitriche stagnalis, Littorella uniflora, Potamogeton natans, Ranunculus trichophyllus, Glyceria fluitans, Chara subspinosa

A14 — Fast flowing river and stream

Myriophyllum alterniflorum community

Isolepis fluitans, Juncus bulbosus, Fontinalis antipyretica, Lobelia dortmanna, Equisetum fluviatile, Myriophyllum alterniflorum, Lemna minor, Callitriche stagnalis, Littorella uniflora, Potamogeton filiformis, Potamogeton gramineus, Potamogeton natans, Ranunculus peltatus, Chara spp., Nitella hyalina

A17 — Chalk river and stream, Fast flowing river and stream

Ranunculus penicillatus ssp. pseudofluitans community

Berula erecta, Nasturtium officinale, Elodea canadensis, Lemna minor, Callitriche stagnalis, Veronica beccabunga, Polygonum amphibium, Polygonum hydropiper, Potamogeton crispus, Potamogeton pectinatus, Ranunculus penicillatus ssp. pseudofluitans

A18 — Fast flowing river and stream

Ranunculus fluitans community

Fontinalis antipyretica, Fontinalis squamosa var. curnowii, Myriophyllum alterniflorum, Myriophyllum spicatum, Elodea canadensis, Mentha aquatica, Lemna gibba, Lemna minor, Potamogeton perfoliatus, Ranunculus fluitans, Glyceria fluitans, Phalaris arundinacea