Bleadon Hill

Site of Special Scientific Interest · 51.3119, -2.9323

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Also within

Somerset County Mendip Hills Scenic Area

Condition (Natural England)

Favourable (1)
UnitFeatureConditionArea (ha)Assessed
ST351573 — Favourable 13.42 2012-12-06

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

Geological Period: Jurassic, Quaternary · Rock Type: Conglomerate

Landscape processes: Coastal, Glacial

Description

Description This site shows a low ridge of calcite cemented Pleistocene sand and gravel on the southern side of Bleadon Hill, separated from the main hill slope by a dry valley. The sands show laminae and ripple marks typical of a waterlain environment. Various marine or glacial origins have been postulated for the sediments and it has even been suggested as the sediments contain Jurassic foraminifers that this is a Mesozoic beach conglomerate. The origin of these sands and gravels, however, still remains equivocal as their occurrence at 82 metres OD is likely to be too high for either an ancient river or beach deposit. On the basis of the sedimentology, it is most likely that these sediments accumulated during the Quaternary Era when an ice sheet rested against Bleadon Hill. Meltwater from this ice sheet deposited sands and gravels across the area the remnants of which form the deposits on the side of Bleadon Hill. This site is important for delineating the southern margins of the Quaternary glaciation, although further research is still needed to fully understand this enigmatic site.

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