Eas na Broige

Site of Special Scientific Interest · 56.6230, -4.9503

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Also within

Inverness County Ben Nevis and Glen Coe Scenic Area 09. Loch Etive mountains Wild Land Area

Condition (NatureScot)

Favourable (2)
UnitFeatureConditionArea (ha)Assessed
F1 Fluvial Geomorphology of Scotland Favourable — 2014-03-03
F2 Quaternary of Scotland Favourable — 2014-03-03

Habitats

Fast flowing river and stream

Geology & landscape

Geological Period: Quaternary

Landscape processes: Fluvial

Description

EAS NA BROIGE Eas na Broige SSSI is located above Alltchaorunn in Glen Etive, 12km south east of Glencoe village. It is a fine example of the landforms associated with fluvial geomorphological processes. In all, three stages of erosion activity are displayed – debris flow, alluvial fan development and contemporary stream erosion. The site is important in the Scottish Highlands for interpreting the historical sequence of events leading to the onset and cessation of each stage of activity. Such changes may be related to changes in land use at the site. The site comprises a relict debris cone and inset alluvial fan. The debris cone was formed by the fall of rocks and sediment from the steep, rock-cut gully above. Subsequent alluvial erosion during the Holocene reworked the sediments resulting in the development of an extensive alluvial fan. The latter displays the classic development of ‘incised’ fans, with three different surfaces inset into one another. The final stage of activity, incision by the present-day stream, clearly demonstrates the stratigraphic relationships between the debris cone and alluvial fan. Radiocarbon dating of organic horizons within fossil soils has provided a chronology for the cessation of debris flow activity and the onset of fluvial erosion. Such a change in geomorphological regime has not previously been identified from the Scottish Highlands.

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