The SSSI extends from Porthcurno beach in the west to Penberth Cove in the east. Several rare plant species occur and the site is of particular importance for its maritime heath. At the last site assessment on 12 August 2010, the SSSI was described as ″Unfavourable recovering″ because scrub and bracken encroachment are diminishing the interest, and the site needs to be grazed. Removal of sycamore would enhance the site as well as the control of other invasive species. Maritime cliff habitat types, National Vegetation Classification, MC1 and MC5need to be added to the notifiable features.
Biological interest
Plant communities
The main habitats are maritime heath and maritime grassland, heath, scrub, flush and deciduous woodland. The maritime heath is dominated by heather, bell heather and western gorse. Maritime grassland occurs on the steeper cliff slopes and is dominated by red fescue, with spring squill, wild carrot, kidney vetch and sea plantain. The Red Data Bookwestern clover and the nationally rare hare's foot clover grow here as well as hairy bird's-foot trefoil and bird's-foot fenugreek. Large areas are covered by scrub, dominated by gorse and blackthorn and provide habitat for invertebrates and birds. Common dodder parasitises the gorse. A number of wet flushes occur along the coast dominated by common reed. A small area of woodland dominated by elm and sycamore has developed on abandoned horticultural plots. A description by Jean Lawman sums up the area eloquently:
Also in June, many of the cliffs are bright with Oxeye DaisiesLeucanthemum vulgare and they are particularly abundant around Logan Rock and Porth Curnow area where they mix with foxgloves and button like, mauve Sheepsbit Jasione montana. The spectacle of all these flowers strewn along the cliff edge, with the classically beautiful Pednevounder beach below and the rugged headland of Treryn Dinas in the distance, must be one of the loveliest in Cornwall.
Rock sea lavender is an endemic plant that is found only along this part of the coast from Carn Les Boel to the Logan Rock. all the colonies are within a SSSI but may be vulnerable from climbers or walkers on the lower slopes where it occurs.
Invertebrates
A nationally rare invertebrate, the weevilAnthonomus rufus, occurs on the cliffs and is associated with blackthorn the larvae almost certainly in the flower buds. Formerly widespread in coastal Britain, now localised. There are butterfly colonies of the silver-studded blue, small pearl-bordered fritillary on Cribba Head in the eastern part of the site as well as the thrift clearwing a day–flying moth.
