River West Allen at Blackett Bridge
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Condition (Natural England)
| Unit | Feature | Condition | Area (ha) | Assessed |
|---|---|---|---|---|
| NY780538 | — | Favourable | 7.31 | 2024-02-22 |
| NY781542 | — | Favourable | 0.8 | 2024-02-22 |
| NY781543 | — | Favourable | 5.41 | 2024-02-22 |
Habitats
Geology & landscape
Landscape processes: Fluvial
Description
Description The River West Allen at Blackett Bridge is representative of the geomorphology of many of the small river valleys that drain the north and north west parts of the northern Pennines. The extent to which valley floors in the area have been reworked by recent lateral channel migration is determined principally by the degree to which the rivers are confined by drift or bedrock. The West Allen at Blackett Bridge exemplifies excellently the effects of these controls. The reach comprises two alluvial basins which have been characterised by comparatively high rates of lateral channel movement and flood plain sedimentation during the last hundred years. In contrast, these basins are separated by a short section where the present day channel is laterally confined by steep drift bluffs. The West Allen is also typical in showing high levels of metal contaminants in historic flood plain and terrace sediments associated with metal mining. Other Information 1. This site is identified as being of national importance in the Geological Conservation Review. 2. Part of this site is also notified as Ninebanks River Shingles SSSI for the interest of its flora.
Plant communities
A9 — Fast flowing river and stream, Marginal and inundation, Pond ditch and canal, Sluggish river and stream
Potamogeton natans community
Show 20 indicator speciesSchoenoplectus 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
Show 15 indicator speciesIsolepis 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
Show 11 indicator speciesBerula 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
Show 12 indicator speciesFontinalis 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