Allt a' Choire

Site of Special Scientific Interest · 57.4139, -3.8892

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Also within

Nairn County

Condition (NatureScot)

Favourable (1)
UnitFeatureConditionArea (ha)Assessed
F1 Fluvial Geomorphology of Scotland Favourable — 2009-07-03

Habitats

Fast flowing river and stream

Geology & landscape

Geological Period: Quaternary · Rock Type: Glacial Till

Landscape processes: Fluvial, Glacial

Description

ALLT A’ CHOIRE The Allt a’ Choire is a small tributary of the River Findhorn, situated on the south-eastern edge of the Drynachan Valley approximately 11 km south of Cawdor. Within a small area of approximately 1.5 square kilometres this upland catchment provides an excellent example of sediment erosion and deposition, clearly demonstrating the relationship between the eroding soils and the sediment deposition in a debris cone and alluvial fan. The bedrock within the Allt a' Choire catchment is overlain by thick deposits of glacial till deposited by the last ice sheet as it retreated. Within the Allt a' Choire catchment there are two main headwaters, to the south and to the east. Both are deeply dissected into the till, which has led to intense gullying of the adjacent hill slopes during periods of extreme rainfall and snow melt. This has resulted in a ‘badlands’ type of environment of unusual extent for Scotland. Several distinct phases of gullying, accumulation of sediments and eventual stabilisation by vegetation are clearly evident. At the base of the active gullies, a debris cone of coarse material has developed. Debris cones are formed from weathered material which moved downslope by mass movement such as landslides. In flood conditions the sediment has been washed out from the debris cone and deposited on an alluvial fan adjacent to the River Findhorn. The alluvial fan is subject to periodic reworking and shows at least four earlier fan surfaces which are considered to date back to the Late Glacial period. These relict alluvial fan surfaces are important because they demonstrate a complex relationship with river terraces which have developed in response to the Late Glacial and Holocene incision of the River Findhorn, most notably at the nearby Findhorn Terraces SSSI.

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