The Dungeon

Site of Special Scientific Interest · 53.3395, -3.1261

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Also within

Merseyside County

Condition (Natural England)

Favourable (1)
UnitFeatureConditionArea (ha)Assessed
SJ251831 — Favourable 1.09 2011-10-18

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 Feature: Gorge / Ravine · Geological Period: Triassic · Rock Type: Mudstone, Sandstone, Siltstone

Landscape processes: Coastal

Description

Area,1.2 hectares 2.8 ac Description The Dungeon is a small wooded ravine a quarter of a mile to the north west of Heswall, which shows a natural stream section through the Tarporley Siltstone Formation of the Mercia Mudstone Group, of Triassic age. At the south west end of the section the faulted contact with the older Wilmslow Sandstone Formation is seen. The Tarporley Siltstone section is similar to that in other parts of the Cheshire basin, being made up of red fine sandstones and siltstones, with parallel and rippled bedding and salt pseudomorphs. Current ripple crests indicate that sediment transport was towards the northwest. Sediments and sedimentary structures in these rocks make it possible to infer that they were deposited in a marine intertidal environment.

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