Area: 371.1 hectares.
Description and Reasons for Notification:
Gwithian to Mexico Towans constitutes the second largest dune system in Cornwall, stretching for approximately three kilometres along the North Cornwall coast from Hayle to Gwithian. These northwest facing dunes rise to a maximum height of over 60 metres. This exposed, dynamic dune system is subject to the full force of Atlantic gales, resulting in several large blow-outs along the seaward margin. This complex and extensive dune system supports a rich and diverse flora.
The dunes are composed of wind-blown calcareous shell sand, giving rise to raw skeletal soils which overlie the fine-grained Devonian slates of the Mylor Series.
This site is important in illustrating successive erosional and depositional phases in coastal development. It contains an assemblage of dunes in the south which are progressively replaced northwards by rock cliffs, caves, stacks and arches; overlain by blown sand and dunes. These erosional features have been exposed, as formerly much larger dunes have eroded. Remnants of former dunes are also preserved on stacks. The site clearly demonstrates the relict nature of the cliffed coastline and allows examination of the interface between dunes and the sub-dune surface.
This extensive dune system supports a number of rare native plant species, including balm-leaved figwort Scrophularia scorodonia and hairy-fruited cornsalad Valerianella eriocarpa, also twiggy mullein Verbascum virgatum, ivy broomrape Orobanche hederae, western clover Trifolium occidentale and autumn lady's-tresses Spiranthes spiralis. Past industrial and agricultural use of these dunes has created additional habitats and led to the introduction of several alien plants, including alkanet Anchusa officinalis, the garden escape garden anchuso Anchusa azurea, yellow alkanet Anchusa ochroleuca and argentine dock Rumex frutescens.
The unstable foredunes support sand couch Elytriga juncea and are backed by an extensive range of fixed dunes, dominated by marram grass Ammophilia arenaria, with species such as red fescue Festuca rubra, kidney vetch Anthyllis vulneraria, wild carrot Daucus carota and sand sedge Carex arenaria. In addition sea spurge Euphorbia paralias and Portland spurge Euphorbia portlandica, which are scarce outside Cornwall, also occur here.
The short turf of the intervening areas of herb-rich calcareous grassland is dominated by grasses, including meadow-grass Poa annua, spreading meadow-grass Poa subcaerulea, early hair-grass Aira praecox and fern grass Catapodium rigidum with associated herb species, such as wild thyme Thymus polytrichus, kidney vetch Anthyllis vulneraria, cowslip Primula veris, and sedge, pyramidal orchid Anacamptis pyramidalis, eyebright Euphrasia officinalis, viper's bugloss Echium vulgare and yellow rattle Rhinanthus minor.
The drier dune-slacks are dominated by red fescue and herbs such as buck's-horn plantain Plantago coronopus, ribwort plantain Plantago lanceolata, wild thyme Thymus praecox, carline thistle Carline vulgaris, and grasses, including dune fescue Vulpia fasciculata, upright brome Bromus erectus and sand cat's-tail Phleum arenarium.
In the wetter dune-slacks southern marsh-orchid Dactylorhiza praetermissa and field horsetail Equisetum arvense commonly occur, together with yellow bartsia Parentucellia viscosa. One particular dune-slack is noted for the occurrence of variegated horsetail Equisetum variegatum.
The small pond on Phillack Towans supports species such as water mint Mentha aquatica, soft rush Juncus effusus, silverweed Potentilla anserina, grey willow Salix cinerea and adder's tongue Ophioglossum vulgatum.
Species associated with the small cliff flushes include water Mmint, fleabane Pulicaria dysenterica, common figwort Scrophularia nodosa, wild angelica Angelica sylvestris and ragged-robin Lychnis flos-cuculi.
Scrub vegetation is scattered throughout the dune system. Species commonly occurring are privet Ligustrum vulgare, bramble Rubus fruticosus, elder Sambucus nigra and european gorse Ulex europeaeus. Dense stands of sea buckthorn Hippophae rhamnoides occur at the back of Phillack Towans. Associated with some of these areas of dune-scrub is the rare balm-leaved figwort Scrophularia scorodonia.
This complex dune system is also of importance for its butterflies and moths, including a form of the silver-studded blue butterfly Plebejus argus, the grayling butterfly Hipparchia semele, and such notable species as white-letter hairstreak Strymonidia album, pearl-bordered fritillary Boloria euphrosyne, silver-washed fritillary Argynnis paphia, and dark green fritillary Argynnis aglaja. Also recorded here is the yellow form of six-spot burnet moth Zygaena filipendulae.
In addition the small pond on Phillack Towans is one of the few locations in Cornwall for the great pond snail Lymnaea stagnalis and an unusual pond snail Lymnaea glabra.