Area: 265.7 hectares.
Partly Biogenetic Reserve. Nature Conservation Review Site. Contains two Geological Conservation Review Sites. Area of Outstanding Natural Beauty. Partly within The Lizard National Nature Reserve. Part owned by the National Trust.
Kennack to Coverack is located some 14 kilometres south east of Helston on the east coast of the Lizard Peninsula, the most southerly tip of mainland Britain. Most of the site is underlain by serpentinite with intrusions of gabbro. Both of these rocks are silica-poor and weather to form gleys and brown earths which are base rich. In the west of the site more recent intrusions of granitic Kennack gneiss occurred, now supporting typical brown earth soils. Alluvium occurs locally in the valleys within the site. Rocks at Kennack Sands provide evidence of the likely sequence of events in the emplacement of the Lizard complex of rocks, while around Lankidden shear zones in gabbro, and dunite veins cutting the peridotite, indicate events in the formation of the Variscan oceanic crust.
The combination of mild oceanic climate together with the unusual geology, soils and varied topography has led to the development of a range of vegetation types which, in Britain, is unique to the Lizard Peninsula. Of particular note is the Red Data Book (RDB) (*) species cornish heath Erica vagans, a plant which is confined in the British Isles to County Fermanagh, Northern Ireland and to the Lizard Peninsula, where it is abundant. Eight other RDB (*) species and sixteen nationally scarce species have been recorded at this site.
The dunes at Kennack are one of only three dune systems on the Lizard and constitute a rare calcareous habitat on the Peninsula. Dominant plants here are sea couch Elytriga atherica and sand sedge Carex arenaria. Lesser meadow-rue Thalictrum minus, a basicole species absent from other Cornish dune systems has strong populations here. A host of rare plants has been recorded here, namely the RDB (*) species fringed rupturewort Herniaria ciliolata, early meadow-grass Poa infirma and Babington’s leek Allium ampeloprasum subsp.babingtonii and the nationally scarce galingale Cyperus longus, suffocated clover Trifolium suffocatum, autumn squill Scilla autumnalis, tree-mallow Lavatera arborea, tall ramping-fumitory Fumaria bastardii, sea radish Raphanus maritimus, upright chickweed Moenchia erecta, Musk stork’s-bill Erodium moschatum and yellow bartsia Parentucellia viscosa.
Semi-natural vegetation stretches inland from the dunes to the heathland of Goonhilly Downs. On the well-drained parts of the valleys, around rock outcrops, stands of 'Mixed Heath' occur. These are dominated by western gorse Ulex gallii, gorse Ulex europaeus and cornish heath, with frequent dropwort Filipendula vulgaris, saw-wort Serratula tinctoria, tormentil Potentilla erecta, bell heather Erica cinerea and wild thyme Thymus polytrichus subsp. arcticus. Closer to the valley streams woodland occurs, parts of which display rich lower plant communities. Further east, Downas Valley supports extensive mixed heath, as well as royal fern Osmunda regalis and great fen-sedge Cladium mariscus, two local species, in the wetter valley floor. Near the head of this valley are two areas of unenclosed heathland supporting a mosaic of mixed heath, 'short heath' and 'tall heath' communities. Tall heath occurs on gleys over serpentinite and is dominated by Cornish heath, black bog-rush Schoenus nigricans and purple moor-grass Molinia caerulea. In places the serpentinite is covered by more acidic loess deposits, over which short heath develops. Dominants here are heath Calluna vulgaris, bell heather, cross-leaved heath, western gorse, purple moor-grass and bristle bent Agrostis curtisii.
At exposed sites, cliffside vegetation displays a clear zonation. Lankidden promontory is the only site on gabbro on the Lizard where this zonation is seen. Lowest down the cliff face a maritime rock-crevice community develops, typical plants being thrift Armeria maritima subsp. maritima and rock samphire Crithmum maritimum. The nationally scarce golden-samphire Inula crithnoides also occurs. Maritime grasslands and heathlands develop further up the cliff, the grasslands usually dominated by red fescue Festuca rubra, or cock’s-foot Dactylis glomerata and Yorkshire-fog Holcus lanatus. Within the maritime heathland plants such as heath, sheep’s-fescue Festuca ovina and cat’s-ear Hypochoeris radicata are common, with the nationally scarce hairy bird’s-foot-trefoil Lotus subbiflorus and thyme broomrape Orobanche alba also present. Particularly important are populations of the RDB (*) species hairy greenweed Genista pilosa, land quillwort Isoetes histrix and the uncommon prostrate broom Cytisus scoparius subsp. maritimus.
Deeper soils over serpentinite support extensive mixed heath, often reaching down the cliff face a considerable way due to the relatively sheltered, easterly aspect of this site. Moderately sheltered parts of these cliff tops support in places a community where bloody crane’s-bill Geranium sanguineum is constant. The unusual soil chemistry on serpentinite appears to be an important factor governing the distribution of this community.
In the most sheltered locations, scrub communities develop with gorse, blackthorn Prunus spinosa and bracken Pteridium aquilinum the dominant species. Nationally scarce ivy broomrape Orobanche hederae and Italian lords-and-ladies Arum italicum have been recorded in scrub here.
Parts of the more level areas of clifftop have been grazed by domestic stock. These sites now hold key populations of the RDB (*) plants dwarf rush Juncus capitatus and twin-headed clover Trifolium bocconei and nationally scarce bird’s-foot clover Trifolium ornithopodioides.
In places along the cliffs the characteristic vegetation zonation is broken by flushes running down the cliff profile. These are usually dominated by black bog-rush and common reed Phragmites australis. One flush supports a strong population of wood small-reed Calamagrostis epigejos -- its only known location in Cornwall. Other parts of the cliff face are masked by clitter slopes, relics of periglacial activity. This site has the most extensive clitter developments on the Lizard and Orpine Sedum telephium occurs here at its only site on the Lizard. Lanceolate spleenwort Asplenium billotii and the RDB (*) plant western ramping-fumitory Fumaria occidentalis have been recorded, the latter thought to be at its only known natural location.
The site is an important refuge for a number of non-vascular plants. Eight rare bryophytes have been recorded, including Gongylanthus ericetorum, black crystalwort Riccia nigrella and entire threadwort Cephaloziella calyculata, three RDB (*) bryophytes found in short, cliff top turf. Cliff top crevices provide a habitat for the Nationally Rare dog screw moss Tortula canescens. The site is also important for lichens, being a Grade II lichen site of the Calluna -- Erica vagans type.
In addition to the rich botanical interest of the site a number of rare invertebrates occur including the RDB (*) mining bee Andrena falsifica and the RDB (*) mason bee Ancistrocerus antilope Libellula fulva, a RDB (*) dragonfly, has been recorded in the Gwendreath valley. Birds also find the area attractive, especially during spring and autumn migration periods when the scrub areas in particular offer useful cover and food. Dartford warbler Sylvia undata and hobby Falco subbuteo have bred here recently.
The Lizard Complex consists of a large serpentinitised peridotite body, cut by later gabbros, basic dykes and granitic veins and having spatial affinities with amphibolitic rocks. Recent interpretations consider the Complex to represent the tectonically juxtaposed remnants of a disrupted ophiolite.
Kennack Sands is the type locality for, and best exposure of, the Kennack Gneiss. The coastal exposures are famous for the display of the complicated contact relationships between the gneiss and the main lizard serpentinite. The complex field relations have led to a variety of contrasting theories as to the origin of the gneiss. Recent interpretations, however, agree that the gneiss formed late in the evolution of the Complex. One such interpretation considers the gneiss to represent a migmatised equivalent of the Old Lizard Head Series and lower Landewednack Schists seen at Lizard Point, developed in response to the early stages of obduction of the Lizard ophiolite.
The cliffs around the prominent headlands at Lankidden show superb examples of high- temperature shear zones along the margins of a coarse gabbro sheet cutting the peridotite. Also in Lankidden Cove are the best examples of dunite veins cutting the peridotite. The exact origin of the veins is unclear but they are probably the pathways of magmas or fluids ascending from deeper mantle levels. Chromite lenses are enclosed within some of the dunite veins.
* These plants and insects are included in the Red Data Book listing of rare and endangered species.