A site of special scientific interest (SSSI) in Great Britain, or an area of special scientific interest (ASSI) in the Isle of Man and Northern Ireland, is a conservation designation denoting a protected area in the United Kingdom and Isle of Man. SSSI/ASSIs are the basic building block of site-based nature conservation legislation and most other legal nature/geological conservation designations in the United Kingdom are based upon them, including national nature reserves, Ramsar sites, Special Protection Areas, and Special Areas of Conservation. The acronym "SSSI" is often pronounced "triple-S I".
Ystradfellte is a village and community in Powys, Wales, about 6 miles (10 km) north of Hirwaun, with 556 inhabitants. It belongs to the historic county of Brecknockshire (Breconshire) and the Fforest Fawr area of the Brecon Beacons National Park, beside the Afon Mellte river. The village is linked by minor roads with Heol Senni to the north and the A4059 north of Penderyn, and with Pontneddfechan, which lies in the community, at the head of the Vale of Neath to the south.
Afon Mellte or the River Mellte is a river in south Wales. It is formed by the confluence of the Afon Llia and the Afon Dringarth. It then flows south through the village of Ystradfellte to Pontneddfechan where it joins with the Nedd Fechan to become the River Neath. The river derives its name from 'mellt' - the Welsh word for 'lightning' - after its tendency to rise and fall rapidly in response to heavy rainfall.
River Neath is a river in south Wales running south west from the point at which its headwaters arising in the Brecon Beacons National Park converge to its mouth at Baglan Bay below Briton Ferry on the east side of Swansea Bay.
Dinas Rock is a high promontory of Carboniferous Limestone which rises between the Afon Mellte and its left-bank tributary, the Afon Sychryd on the border between the county of Powys and the county borough of Neath Port Talbot in south Wales. It can be found near the village of Pontneddfechan near Glyn Neath at the head of the Vale of Neath. It derives its name from the presence of Iron Age earthworks on its summit, dinas in Welsh signifying a defensive site or "city".
Craig y Llyn is a mountain situated to the south of the village of Rhigos in the Cynon Valley on the south side of the upper Vale of Neath and north of the Rhondda Valleys in South Wales; it is the highest point in the ancient kingdom and, later, county of Glamorgan (Morgannwg), and the southern Welsh coalfield plateau.
Whitecliff Bay and Bembridge Ledges is a 131.6-hectare (325-acre) Site of Special Scientific Interest that lies around the coastline of the easternmost part of the Isle of Wight from the Bembridge harbour entrance in the north around Foreland to Whitecliff Bay to the south. The site was notified in 1955 for both its biological and geological features.
The Nedd Fechan is a river almost wholly within the county of Powys, Wales, currently administered as part of the unitary authority of Powys. It rises on the eastern slopes of Fan Gyhirych in the Fforest Fawr section of the Brecon Beacons National Park and flows south for 7 miles (12 km) to join with the Afon Mellte at Pontneddfechan, their combined waters continuing as the River Neath to the sea near Swansea. The only significant tributary of the Nedd Fechan is the Afon Pyrddin which joins it at Pwll Du ar Byrddin. Downstream of this confluence it forms the boundary between Powys to its east and Neath Port Talbot to its west.
Moel Penderyn is a hill on the edge of Penderyn village, in the Brecon Beacons National Park in the county borough of Rhondda Cynon Taff, south Wales. It also appeared on older maps as 'Y Foel Penderyn'. Its summit at 371m is marked by a trig point.
Mynydd Llangynidr is a mountain in the Brecon Beacons National Park largely in the county of Powys, south Wales. Its southern slopes extend into the northernmost parts of the county borough of Blaenau Gwent. It is named from the village of Llangynidr which sits in the valley of the River Usk to the north of it. It is essentially an undulating plateau rising in the west to a height of 557m at Garn Fawr at OS grid ref SO 123151. A secondary high point is achieved at a point marked by a trig point at SO 147159. To the north the hill overlooks the valleys of Dyffryn Crawnon and Cwm Claisfer, themselves tributary valleys of the Usk. The shallow upper valley of the Ebbw River reaches into the plateau in the southeast whilst the upper reaches of the Sirhowy Valley and its tributary the Nant Trefil define its western margins. A further tributary, the Nant Milgatw, reaches in from the south whilst the sharp edge of Rassau Industrial Estate also defines a part of its southern margin. Passing east across the B4560, the hill merges with Mynydd Llangatwg which has a similar character.
Waterfall Country is an English name often given to the Vale of Neath in South Wales. The tourist area around the head of the valley has an unusually large number of publicly accessible waterfalls. The area is not officially defined but generally includes the group of falls on the Nedd Fechan, Pyrddin, Hepste and Mellte rivers, all of which lie between the villages of Pontneddfechan and Ystradfellte in the Brecon Beacons National Park.
Elenydd is an upland area of Mid Wales, extending across parts of northern and eastern Ceredigion and Powys between Aberystwyth and Rhayader. Elenydd is also a name given to the medieval commote of Cwmwd Deuddwr which covered approximately the same area.
Newport Cliffs is a Site of Special Scientific Interest lying a little to the north of Newport in Pembrokeshire, South Wales. It has been designated as a Site of Special Scientific Interest since January 1954 in an attempt to protect its fragile biological elements. The site has an area of 48.23 hectares and is managed by Natural Resources Wales.
Strumble Head - Llechdafad Cliffs is a Site of Special Scientific Interest (SSSI) in Pembrokeshire, South Wales. It has been designated as a SSSI since January 1954 in an attempt to protect its fragile biological and geological elements.
Afon Seiont is a Site of Special Scientific Interest in West Gwynedd, Wales. It is protected by law and has been designated as a Site of Special Scientific Interest since July 1997 in an attempt to protect rare or unique features or species within it. The site has an area of 6.4 hectares and is managed by Natural Resources Wales. This site is designated due to its geological qualities. In Wales, geological sites range from quarries to rocky outcrops and massive sea-cliffs. 30% of SSSIs in Wales are notified for geological and geomorphological features.
This article describes the geology of the Brecon Beacons National Park in mid/south Wales. The area gained national park status in 1957 with the designated area of 1,344 km2 (519 sq mi) including mountain massifs to both the east and west of the Brecon Beacons proper. The geology of the national park consists of a thick succession of sedimentary rocks laid down from the late Ordovician through the Silurian and Devonian to the late Carboniferous period. The rock sequence most closely associated with the park is the Old Red Sandstone from which most of its mountains are formed. The older parts of the succession, in the northwest, were folded and faulted during the Caledonian orogeny. Further faulting and folding, particularly in the south of the park is associated with the Variscan orogeny.
