CITATION DURNESS SITE OF SPECIAL SCIENTIFIC INTEREST Highland (Sutherland) Site code: 580 NATIONAL GRID REFERENCE: NC 380670 OS 1:50,000 SHEET NO: Landranger Series 9 1:25,000 SHEET NO: Explorer Series 446 AREA: 2000.97 hectares NOTIFIED NATURAL FEATURES Geological : Stratigraphy : Arenig-Llanvirn : Cambrian-Tremadoc : Structural and : Moine metamorphic geology : Geomorphology : Coastal geomorphology of Scotland Biological : Freshwater habitats : Base-rich loch : Upland habitats : Dryas heath : Non-montane rock : Limestone pavement habitats : Coastlands : Maritime cliff : Sand dunes DESCRIPTION Durness Site of Special Scientific Interest (SSSI) lies near the settlement of Durness, 15km east of Cape Wrath on the northwest tip of the Scottish mainland. It is of national importance for its geology and for a number of habitats associated with the Durness limestone that underlies much of the site. Arenig-Llanvirn (geology) The youngest part of the Cambrian-Ordovician rock sequence (Arenig-Llanvirn age, ~490-470 million years ago) is also known as the ‘Durness Group’. These rocks consist of limestone and magnesium-rich limestone known as dolomite. Much of the Durness SSSI forms the ‘type locality’ for the Durness Group. Fossils of ancient molluscs are abundant within the sediments of the upper part of the Durness Group. These are similar to fossils of the same age from North America and Greenland but very different from those found in Wales. This provides strong evidence that during the early Ordovician, Scotland formed part of the same continental landmass as North America and Greenland and was divided from Wales and England by a wide ocean. This site is therefore important in understanding ancient faunas and palaeogeography, and is crucial in correlating rocks that occur on either side of the Atlantic. Cambrian-Tremadoc (geology) The oldest parts of the Cambrian and Ordovician sedimentary rock sequence (Cambrian-Tremadoc age, ~540-490 million years ago) are exposed on the west Page 1 of 3 shore of the Kyle of Durness, north of Daill. Junctions known as ‘unconformities’, separate rocks of different ages. The rocks include Lewisian gneiss which is up to 3 billion years old, billion year old Torridonian sandstone, and Cambrian quartzites which are the oldest rocks of the Cambrian-Ordovician sequence. Moine (geology) The Moine rocks of Faraid Head are metamorphic schists. These formed from silt and mud deposited in an ocean at the edge of a continent. The sediments were buried, compressing them to rock, which was then subjected to intense heat and pressure associated with plate tectonic activity. During continental collisions around 430 million years ago, Moine schists were forced westwards over other rocks along a fault or fracture called the Moine Thrust. Most of the Moine rocks to the west of Loch Eriboll have been eroded away leaving the outcrops at An Fharaid as the most westerly outlier of the Moine rock in Scotland. These rocks are significant because they demonstrate how far westward Moine rocks were moved along the Moine Thrust and they have played an essential part in our understanding of this major geological structure and the formation of the Northwest Highlands. Coastal geomorphology of Scotland The peninsula of An Fharaid encloses Balnakeil Bay and lies at the entrance to the Kyle of Durness. It contains a spectacular array of beach and dune landforms, ranging from undercut dune face to large and active dune blowthroughs. Large blowthrough corridors and mobile sand waves carry windblown sand across An Fharaid peninsula, from the beaches on the west coast to a prominent cliff on the east of the site. Coastal grassland has stabilized much of the blown sand deposits on the higher slopes in the north and east of the peninsula. These contrast with the lower altitude, highly active dunes and blowthrough corridors. The dunes at Balnakeil are some of the most active in Scotland. Base-rich loch Four marl lochs (Lochs Lanlish, Croispol, Borralie and Caladail) and the burns forming the inflow and outflow of Loch Croispol, lie on the Durness limestone. The lochs are clear and shallow and have stony shorelines with very little marginal vegetation. However, there are extensive growths of submerged vegetation including seven species of pondweed Potamogeton and three species of stonewort Chara. Dryas heath The coastal grasslands grade into heathland communities on the Balnakeil headland where wind-pruned heaths grow on exposed summits. Mountain avens Dryas octopetala heath occurs amongst the limestone outcrops on calcareous soils. This is a rare upland community and Durness provides one of the best examples of Dryas heath in Britain. Other montane species associated with the Dryas heaths include alpine bistort Persicaria vivipara, yellow mountain saxifrage Saxifraga aizoides, twisted whitlow-grass Draba incana, hair sedge Carex capillaris and crowberry Empetrum nigrum ssp. hermaphroditum. Limestone pavement (vegetation) Durness is one of only four sites with relatively extensive limestone pavement in Scotland and of these it is has the second greatest number of plant species. Around Page 2 of 3 Loch Borralie, the limestone pavement supports a rich flora. There is a mixture of lowland or southern species, such as hairy rock cress Arabis hirsuta, broad leaved helleborine Epipactis helleborine, burnet rose Rosa pimpinellifolia and lesser meadow rue Thalictrum minus, and more northern species such as green spleenwort Asplenium viride, stone bramble Rubus saxatilis and holly fern Polystichum lonchitis. Maritime cliff (vegetation) The cliff tops and ledges of An Fharaid and Eilean Dubh support a range of salt- tolerant plants, including sea campion Silene uniflora, thrift Armeria maritima and a variety of plantain species Plantago spp. The ledges are largely inaccessible to sheep and rabbits and, in the absence of grazing, tall stands of grasses, thrift, Scots lovage Ligusticum scoticum and roseroot Sedum rosea have developed. Sand dunes (vegetation) The Kyle of Durness which opens out into Balnakeil Bay is very shallow, with extensive sandflats exposed at low water. Much of the material in these sandflats was deposited by glaciers or glacial meltwater. This is the source of the sand which feeds most of the dunes between Keoldale and Balnakeil and those on the isthmus leading to An Fharaid. The dune systems encompass the full transition from mobile dunes on the foreshore, to fixed dunes dominated by marram grass, through to more herb-rich climbing dunes and coastal grassland further inland. NOTIFICATION HISTORY First notified under the 1949 Act: 1963 Re-notified under the 1949 Act : 1974 as part of Cape Wrath - Aodann Mhor SSSI incorporating Borralie SSSI and Balnakeil SSSI. Re-notified under the 1981 Act as Durness SSSI: 21 February 1990 with a 1928ha decrease in area Notification reviewed under the 2004 Act: 3 June 2010 Citation revised: 11 March 2011 REMARKS Measured area of site corrected from 1997 ha. Part of Durness SSSI is also designated as Durness Special Area of Conservation (SAC) for the European habitats and species listed below. Habitats : Alpine and subalpine calcareous grasslands Base-rich fens Calcium-rich nutrient-poor lakes, lochs and pools Dry heaths Dune grassland Humid dune slacks Limestone pavements Shifting dunes with marram Tall herb communities Wet heathland with cross-leaved heath Species : Otter Lutra lutra Page 3 of 3 .