GAMRIE AND PENNAN COAST Site of Special Scientific Interest SITE MANAGEMENT STATEMENT Site code: 666 Address: Inverdee House, Baxter Street, Torry, Aberdeen AB11 9QA Tel: 01224 266500 email: [email protected] Purpose This is a public statement prepared by SNH for owners and occupiers of the SSSI. It outlines the reasons it is designated as an SSSI and provides guidance on how its special natural features should be conserved or enhanced. This statement does not affect or form part of the statutory notification and does not remove the need to apply for consent for operations requiring consent. We welcome your views on this statement. Description of the site Gamrie and Pennan Coast SSSI is important for both its biological and geological interests. These interests and their management are described in greater detail below. Geology The rocks exposed in the western end of Gamrie and Pennan Coast SSSI are metamorphic rocks (those which have been altered by heat and pressure) belonging to the Dalradian Supergroup. These rocks were originally formed late in the Precambrian between 800 and 600 million years ago, when they were deposited as sediments on the edge of an ancient ocean. Then, between 500 and 400 million years ago, continental collision closed the ocean building a chain of mountains that may have been similar to the Alps in scale. During this mountain-building event the Dalradian rocks were buried deep within the Earth, where they were metamorphosed and deformed. Because the rocks were buried at different depths, the amount of metamorphism is variable across the outcrop of the Dalradian. The western part of this SSSI (west of Troup Head) contains part of the classic and nationally important Banffshire Coast section, which provides exposures of almost the entire rock sequence of the Dalradian Supergroup. This section has only been metamorphosed at relatively low pressures, and so we can still see many sedimentary features which provide information about the conditions under which the rocks were originally formed. Also exposed within the site are folds in the rock layers, which were formed during the mountain-building episode. Therefore, the rocks of the SSSI provide an abundance of information about the rock sequence of the Dalradian, the environment in which it was deposited, and the conditions under which it was deformed and metamorphosed. The Dalradian interest is therefore of great importance for both research and education. In Gamrie Bay, Pennan Bay and Aberdour Bay, north of New Aberdour, much younger rock occurs. This is ‘Old Red Sandstone’ rock that formed in the Lower Devonian time period (416-398 million years ago) and the Middle Devonian time period (398-385 million years ago). The Lower Devonian rock is known as the ‘Crovie Group’ and the Middle Devonian Page 1 of 5 A1857413.doc rock is known as the ‘Gardenstown Formation’ (but was formerly known as the ‘Findon Group’). These rocks formed from sand and silt eroded from the nearby mountains composed of Dalradian rock. Much of what is now the north east of Scotland was a large depression in the landscape, known as the ‘Orcadian Basin’, into which rivers flowed and in which a lake of varying size periodically formed. Thick layers of river sediments built up in the basin, varying from pebbly alluvial fan deposits to muddy flood plain deposits. If an area of the basin was encroached upon by the lake, then fine-grained muddy lake sediments were deposited. The Devonian rocks are very well exposed in this SSSI, and the contact between the Crovie Group and the Gardenstown Formation can be clearly seen, particularly in the lower part of the cliff west of Pennan. This contact is known as an ‘unconformity’ (or ‘unconformable contact’), because a lot of time passed between the formation of the rocks of the Crovie Group and the deposition of the sediments that formed the Gardenstown Formation. In this time, the Crovie Group rocks were faulted and eroded; so the first sediments of the Gardenstown Formation were deposited on an uneven, eroded surface. Within the Crovie Group rock at Gamrie Bay, are red sandstones with preserved ripple marks and fine examples of trace fossils produced by arthropods (joined-limb animals such as modern day crabs, insects and spiders) These include walking and foraging tracks, burrows, and ‘resting traces’ where the arthropod stopped on the once soft sediment. At nearby Geordie Craigs SSSI, a layer fine-grained shales (including a horizon with fossil fish), within the Gardenstown Formation, records a period when the area was flooded by a lake. However, this layer is not present in the rocks of the Gardenstown Formation in Gamrie Bay. At Den of Findon, the top of the lake-sediment sequence has been eroded prior to the overlying layers of the Gardenstown Formation being deposited, and it is likely that similar erosion, by high-energy rivers, removed all of the lake-deposited layer in the Gamrie Bay area before further river sediments were deposited. The scientific interest at Castle Hill, south west of Gardenstown, lies in a sequence of deposits dating from the Ice Age (the Quaternary period comprising the last 2.6 million years). The deposits exposed in the cliff sections are nationally important for understanding the glaciation of the Moray Firth coast of North-east Scotland. They include a complex sequence of shelly clay, till and sand that consists of ‘rafts’ of material transported onshore from the floor of the Moray Firth by ice moving south-eastwards. The properties of these rafts are particularly interesting for understanding the processes of deposition and deformation (glaciotectonic processes) underneath a glacier. An overlying layer of silt is believed to have formed in a lake dammed against the ice as it retreated to the north-west. The deposits at Castle Hill have a long history of study since the mid-19th century, and the site remains a key locality for interpreting the glaciation of this part of Scotland and the mechanisms of deformation and emplacement of glacially rafted soft sediments. Biology The site supports seabird colonies totalling well over 20,000 individual breeding seabirds. This number includes important breeding populations of the following migratory species: kittiwake (15,000, 3% of the British population, guillemot (22,000, 3% GB), and razorbill (2,000 individuals, 3% GB), when the site was re-notified in 1985. The site also has the only mainland gannet colony in Scotland and 2% of the British breeding population of herring gulls. The European importance of these colonies was recognised by the designation of Troup, Pennan and Lion’s Heads as a Special Protection Area. In 2009 this SPA was recently extended by 2 km into the marine environment. The steep slopes support a particularly diverse coastal and heathland flora including montane species such as purple and mossy saxifrages and roseroot. Although not notified as special features of the SSSI, some of the dens contain good examples of flushes, scrub Page 2 of 5 A1857413.doc and herb-rich grassland, and several regionally rare plants are locally common including spring squill and oysterplant. Natural features of Feature condition Other relevant Gamrie and Pennan Coast SSSI (date monitored) designations Dalradian Favourable, maintained (July 2010) Non-marine Devonian Favourable Maintained (October 2013) Quaternary of Scotland Favourable, maintained (September 2013) Maritime cliff Favourable, maintained (September 2000) Fulmar, breeding Unfavourable, declining SPA (July 2007)* Gannet, breeding Not yet monitored Guillemot, breeding Favourable, declining SPA (July 2007) Kittiwake, breeding Unfavourable, no change SPA (July 2007) Puffin, breeding Not yet monitored Razorbill, breeding Favourable, declining SPA (July 2007) Seabird colony, breeding Favourable, declining SPA (July 2007) *Monitored for the SPA Features of overlapping Feature condition Designation Natura sites that are not notified (date monitored) (SAC or SPA) as SSSI natural features Herring gull, breeding Unfavourable, no change SPA (July 2007) The Dalradian feature was assessed as favourable maintained in 2010. As noted in the previous cycle, there have been some minor changes to the site since it was notified in 1985, including the addition of coastal defences and some dumping, none of which significantly affected the feature. The assessment of the Non-marine Devonian feature in 2013 noted that the area is susceptible to coastal erosion and landslip; however these were not adversely affecting the feature. Guillemots, kittiwakes, razorbills and almost all the other major seabird species present at the site are either declining or already unfavourable. The only species that have increased in number are shag and gannet. There has been a national trend for decline in seabird colonies. The decline is not thought to be caused by a problem on-site. The maritime cliff was assessed as in favourable condition in September 2000, though there were concerns that indicators of nutrient enrichment were present and that the site might decline without some management. Past and present management The area of special biological interest is largely restricted to a narrow band along the coast by agricultural improvement of the flat cliff-top hinterland. The Dalradian geological interests are exposed along the rocky shore and the cliff faces, whilst the Quaternary interest is located at Castle Hill. The site, therefore, retains much of its interest because of its Page 3 of 5 A1857413.doc topography. Much of the site is steep and unsuitable for agricultural improvement, and in places cliffs make access from the inland plateau to flatter areas difficult. Coastal protection work was carried out at Gardenstown in 1995 as a consented activity. Wastewater treatment upgrades for Gardenstown carried out in 2001-2 included an outfall and small pumping station on the foreshore. The boundary of the site for the most part runs along field boundaries at the top of steep cliffs.