Area: 152.28 hectares.

A new site. In Cornwall Area of Outstanding Natural Beauty: In Cornwall Heritage Coast. Contains a Geological Conservation Review site. Part owned by The National Trust. 

* These plants are included in the Red Data Book listing of rare and endangered species.

Description and Reasons for Notification: 

Introduction 

Baulk Head to Mullion is located some 7 kilometres south of Helston on the west coast of the Lizard Peninsula, the southern most part of the British mainland. Most of the site lies on Devonian sedimentary rocks of the Meneage district, but in the south metamorphic rocks of the Lizard district underlie the site. Much of the rock exposure here is of special importance in the study of the relationships between these two distinctive geological regions. The reedbeds here are the second most extensive in Cornwall and harbour a number of uncommon breeding birds, including Cetti’s warbler Cettia cetti

Biology 

Maritime grasslands occupy much of the exposed clifftop, the dominant species being red fescue Festuca rubra, cock’s-foot Dactylis glomerata and Yorkshire-fog Holcus lanatus. Thrift Armeria maritima subsp. maritima and sea carrot Daucus carota subsp. gimmifer grow in these grasslands. In places where the brown earth soils are shallower, plant communities with an abundance of annual species such as English Stonecrop Sedum anglicum and sea mouse-ear Cerastium diffusum are present: Rare plants such as western clover Trifolium occidentale and autumn squill Scilla autumnalis occur in some of these stands. One such stand supports the most northerly population on the Lizard of the RDB (*) plant fringed rupturewort Herniaria ciliolata. This is a curiously isolated population to the north of the Lizard geological district, where it grows more abundantly. 

On some of the cliff faces a maritime rock-crevice community occurs, with highly salt-tolerant species such as thrift and rock samphire Crithmum maritimum characteristic. One crevice contains the only Lizard population of the nationally scarce rock sea-lavender Limonium binervosum. Other rare plants occur in the south of the site where an outcrop of silica poor serpentinite occurs. These include the RDB (*) hairy greenweed Genista pilosa and scarce plants such as spring sandwort Minuartia verna and thyme broomrape Orobanche alba

Where cliff topography affords more shelter, scrub can develop on the clifftops. Blackthorn Prunus spinosa is usually the most abundant species but sometimes gorse Ulex europaeus or bracken Pteridium aquilinum dominate.

At Church Cove and Poldhu Cove vegetation reaches onto the beach. Behind the high tide mark strand line vegetation with spear-leaved orache Atriplex prostrata, sea rocket Cakile maritima and sea sandwort Honkenya peploides occurs. In a further cove, there are records of the Schedule 8 species, shore dock Rumex rupestris and in another location, the only population of an additional Schedule 8 species, sea knotgrass Polygonum maritimum survives. Further back, foredunes exist, dominated by sea couch Elytriga atherica but with populations of sea bindweed Calystegia soldanella, sand sedge Carex arenaria and sea-holly Eryngium maritimum also present The sand dune system further inland is the largest on the Lizard and supports a number of calcicole species, such as salad burnet Sanguisorba minor subsp. minor, which are rare in the Lizard area. 

Species poor red fescue dominated grasslands occupy some areas of the dune, gradually merging into wet grassland on the edge of the reedbeds and marsh. Strawberry clover Trifolium fragiferum and tubular water-dropwort Oenanthe fistulosa occur in the wet grassland. These are two very local species in Britain. Nationally scarce corky-fruited water-dropwort Oenanthe pimpinelloides and Galingale Cyperus longus occur also. Three species rare in Cornwall, horned pondweed Zannichellia palustris, blunt-fruited water-starwort Callitriche obtusangula and lesser pond-sedge Carex acutiformis grow in the streams here. The only recent record on the Lizard Peninsula of RDB (*) wild leek Allium ampeloprasum subsp. ampeloprasum was made in the marsh near Poldhu Bridge. 

The common reed Phragmites australis dominated reedbeds are an extremely important habitat for birds. A number of species of warbler Sylviidae breed including reed warbler Acrocephalus scirpaceus, sedge warbler A. schoenobaenus, grasshopper warbler Locustella naevia and the rare Cetti’s warbler. Savi’s warbler Locustella luscinoides may well breed here occasionally. The secretive water rail Rallus aquaticus is also thought to breed here. Other birds use the marshland as feeding grounds, particularly during spring and autumn migration when species such as the swallow Hirundo rustica and house martin Delichon urbica congregate to feed on airborne invertebrates. The declining sand martin Riparia riparia, which nests in the periglacial head deposits of the local cliffs, feeds over the marshland throughout the summer. 

Six species of dragonfly Odonata spp. have been recorded here including the scarce emperor dragonfly Anax imperator. Several rare mosses reside in this site including the RDB (*) Pottia starkenna subsp. starkenna var. brachyodus

Geology
Gunwalloe Coastal Section

This site exposes sections through presumed late Middle-Upper Devonian Meneage Formations (Gramscatho Group). It shows the transition from well-bedded greywackes to large-scale melange deposits containing phacoides up to 100 metres long. The bedded sediments at Halsferran Cove contain a bed-parallel unit of greywacke melange, which clearly indicates a sedimentary origin for this unit and the other more chaotic deposits seen in the formation. In addition, there are areas of polymict melange with included igneous blocks. The site is of great importance for the study of the complex relationships between the Devonian rocks of this region and the mechanics of the emplacement of the Lizard ophiolite.