Browgill & Stockdale Becks

Site of Special Scientific Interest · 54.4440, -2.7873

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Also within

Cumbria County LAKE DISTRICT National Park

Condition (Natural England)

Favourable (1)
UnitFeatureConditionArea (ha)Assessed
NY490056 — Favourable 26.51 2021-11-04

Habitats

Fast flowing river and stream

Geology & landscape

Geological Period: Ordovician, Silurian · Rock Type: Rhyolite

Landscape processes: Volcanic / Igneous

Description

Description Browgill and Stockdale Becks are situated approximately ten kilometres north of Kendal at the northern end of the Longsleddale valley. The site, which is of geological interest, extends for one kilometre up each stream and includes the south and west facing slopes of great Howe. The Stockdale or Yarlside Rhyolite is the only well developed product of volcanism in the Lake District which post dates the extensive Borrowdale Volcanic Group. The rhyolite dates from Ashgill times late Ordovician and is the surface expression of the subterranean activity which produced the Eskdale and Ennerdale granites and marked the final stages of the Caledonian igneous phase in the area. In the Stockdale Beck and on the hill between the beck and Sadgill in Longsleddale, the rhyolite comprises not just one lava but several units, illustrating a complex volcanic history, including tuffs, various types of rhyolite lava and ignimbrites welded tuffs. Browgill Beck provides an almost complete section through the overlying Llandovery Lower Silurian Stockdale Shales, the Browgill Beds for which this is the type locality and the Brathay Flags above. Minor rhyolitic lava flows occur in the Browgill Beds. This is the type locality for the Monograptus turriculatus and M. crispus biozones, based on graptolite faunas collected here. This is therefore a key site for geological studies of the early Silurian.

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