Crawton Bay

Site of Special Scientific Interest · 56.9071, -2.1973

Open in the interactive map →

Also within

Kincardineshire County

Condition (NatureScot)

Favourable (2)
UnitFeatureConditionArea (ha)Assessed
F1 Non-marine Devonian Favourable — 2014-03-14
F2 Old Red Sandstone Igneous Favourable — 2009-07-14

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 Period: Devonian, Silurian · Rock Type: Conglomerate, Sandstone

Landscape processes: Coastal, Volcanic / Igneous

Description

CRAWTON BAY Crawton Bay is located on the east coast of Aberdeenshire about 6 km south of Stonehaven. The site is the type locality of the Crawton Volcanic Formation, the youngest formation of the Crawton Group which comprises part of the Lower Old Red Sandstone succession in this area of the Midland Valley. The formation consists of volcanic lavas (olivine-bearing basalts and basaltic andesites) and interbedded river-deposited conglomerates of late Silurian to Early Devonian age. Exposure of the lavas is unusually fine, and features such as large elongate plagioclase crystals (phenocrysts) aligned with the direction of lava flow, and superb polygonal cooling joints, are locally well displayed. The persistent nature of the formation makes it an invaluable stratigraphic marker horizon. The Crawton Volcanic Formation is underlain by the Whitehouse Conglomerate Formation and overlain by the Catterline Conglomerate Formation. Rock clasts within the conglomerates indicate that sediment sources differ from those identified for younger sediments in the same area. This gives important information on adjacent mountain uplift and erosion patterns over time. The conglomerates in all three formations provide evidence for the large size and braided stream character of the river systems that were interrupted by the volcanic outpourings preserved in the Crawton Volcanic Formation. The site clearly shows the relationships between volcanic and sedimentary rocks, and is widely used for teaching purposes.

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