Area: 342.8 hectares.
Area to north of county boundary notified as Marsland to Blackchurch Rock SSSI. Previously two separate sites: Steeple Point to Blackchurch Rock and Marsland Mouth. Majority of the site is within both the North Cornwall Heritage Coast and North Cornwall Area of Outstanding Natural Beauty.
Description and Reasons for Notification:
This section of the north Cornwall coastline stretching from Steeple Point 5.5 km northwards to Marsland Mouth on the Devon border supports a rich and diverse flora and fauna associated with a wide range of habitats. Oceanic flora is well represented on this exposed west-facing coastal site.
This site is underlain by Upper Carboniferous Culm Measures, comprising of well-bedded shales and siltstones. Differential weathering of the strata has resulted in the formation of a series of deep-sided east-west trending stream valleys, some of which terminate abruptly at the coast in waterfalls, up to 15 metres high. While others have formed wider, deeper valleys with small alluvial flats, such as at Duckpool to the south. Elsewhere the coastline consists of steep high cliffs rising to some 137 metres at Henna Cliff near Morwenstow. Along the foreshore differential erosion of the highly folded strata has formed prominent rocky reefs running at right angles to the coast together with numerous intertidal and offshore stacks and skerries.
The range of habitats between Steeple Point and Marsland Mouth include rocky foreshore and cliffs, streams, ponds, flushes, grassland, heath, scrub and woodland.
Several uncommon plant species occur here, include monks-hood Aconitum anglicum, the prostrate form of dyer's greenweed Genista tinctoria, wavey-leaved St John's wort Hypericum undulatum, Portland spurge Euphorbia portlandica, rock sea-lavender Limonium binervosum and an unusual range of the colour forms of kidney vetch Anthyllis vulneraria.
The narrow margin of maritime grassland along the cliff edge supports species such as red fescue Festuca rubra, Tthrift Armeria maritima, buckshorn plantain Plantago coronupus, carline thistle Carlina vulgaris and wild thyme Thymus polytrichus.
The steep sided valleys support maritime grassland and maritime heath and their seaward margins grading into scrub and woodland further inland.
The Maritime Heath supports species such as red fescue Festuca rubra, heather Calluna vulgaris, bell heather Erica cinerea, western gorse Ulex gallii, wild thyme Thymus polytrichus, yarrow Achillea millefolium, eyebright Euphrasia virgusii, burnet rose Rosa pimpinellifolia and cat's ear Hypochaeris radicata.
Further inland, scrub, with abundant bracken Pteridium aquilinum and bramble Rubus fruticosus is succeeded by woodland. The most extensive woodland, including areas of ancient woodland, is located in the Marsland valley, where there are large areas of sessile oak Quercus petraea coppice; with some beech Fagus sylvatica, sycamore Acer pseudoplatanus and ash Fraxinus excelsior. Stands of alder Alnus glutinosa occur along the valley bottom.
This coastal site is also of particular importance for its rich invertebrate fauna. The diverse butterfly population includes such uncommon species as Ggrayling Hipparchia semele and high brown fritillary Argynnis cydippe, marsh fritillary Euphydryas aurinia, pearl-bordered fritillary Boloria euphrosyne, small pearl-bordered fritillary Boloria selene, silver-washed fritillary Argynnis paphia, dark green fritillary Argynnis aglaja, brown hairstreak Thecla betulae, dingy skipper Erynnis tages and grizzled skipper Pyrgus malvae. In addition this part of the Cornish coastline also supported one of the last known breeding colonies of the large blue butterfly Maculinea arion, a species which is now believed to be extinct in Britain. The nationally rare dipteran species Paraclusia trigina occurs in one of the side valleys; whilst the open water in the Marsland valley is of particular importance for 14 species of dragonflies. An uncommon woodlouse, Halophiloscia couchii has been recorded on the pebble/boulder beach at Marsland Mouth.
Steeple Point to Marsland Mouth supports a high number of breeding bird species; woodland species include buzzard Buteo buteo, sparrowhawk Accipter nisus, dipper Cinclus cinclus and wood warbler Phylloscopus sibilatrix, with great black-backed gull Larus marinus, rock pipit Anthus spinoletta and stonechat Saxicola torquata along the coast.