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Carreg Cennen Castle is a castle sited on a high rocky outcrop overlooking the River Cennen, close to the village of Trap, four miles south east of Llandeilo in Carmarthenshire, Wales. Castell Carreg Cennen means castle on a rock next to Cennen, the river name itself being a reference either to cen meaning lichen or perhaps a personal name.
Carboniferous Limestone is a collective term for the succession of limestones occurring widely throughout Great Britain and Ireland that were deposited during the Dinantian Epoch of the Carboniferous Period. These rocks formed between 363 and 325 million years ago. Within England and Wales, the entire limestone succession, which includes subordinate mudstones and some thin sandstones, is known as the Carboniferous Limestone Supergroup.
The geology of Wales is complex and varied; its study has been of considerable historical significance in the development of geology as a science. All geological periods from the Cryogenian to the Jurassic are represented at outcrop, whilst younger sedimentary rocks occur beneath the seas immediately off the Welsh coast. The effects of two mountain-building episodes have left their mark in the faulting and folding of much of the Palaeozoic rock sequence. Superficial deposits and landforms created during the present Quaternary period by water and ice are also plentiful and contribute to a remarkably diverse landscape of mountains, hills and coastal plains.
The Neath Disturbance is a geological structure which stretches across south Wales from Swansea Bay northeastwards as far as Hereford in western England. It consists of a series of both faults and associated folds which were active during the mountain-building period known as the Variscan orogeny. This line of weakness probably featured in the earlier Caledonian Orogeny and perhaps reflects a more ancient line of weakness in the basement rocks.
Cribarth, sometimes referred to as the Sleeping Giant, is a hill in the Brecon Beacons National Park, Powys, Wales, in the traditional county of Brecknockshire. The summit lies on the broken ridge at an elevation of 428 m (1,404 ft) at OS grid reference SN 831143. To its west is a 426-metre-high (1,398 ft) rounded top at SN 829144 which lies just to the northwest of a mile-long ridge that forms the main bulk of the hill. The ridge attains a height of 423 m (1,388 ft) at its southwest end and this spot is marked by a trig point. Both of these latter high points are adorned by Bronze Age burial cairns.
The Cribarth Disturbance is a geological structure forming a lineament which stretches across south Wales from Swansea up the Swansea Valley then northeastwards to Brecon and beyond. It consists of both a series of faults and associated folds which were active during the mountain-building period known as the Variscan orogeny. This line of weakness probably featured in the earlier Caledonian Orogeny and perhaps reflects a more ancient line of weakness in the basement rocks. It is also known as the Tawe Valley Disturbance or the Swansea Valley Disturbance.
The Carreg Cennen Disturbance is a zone of geological faults and folds in south and mid Wales which forms a part of both the Church Stretton Fault Zone and the Welsh Borderland Fault System. To the southwest it is known as the 'Llandyfaelog Disturbance'.
Carreg Dwfn is a hill four miles southeast of Llandeilo and just to the south of the village of Trap in the county of Carmarthenshire, south Wales. It lies at the western extremity of the Brecon Beacons National Park and Fforest Fawr Geopark. Its summit at 283 metres (928 ft) is towards the eastern end of a rocky east-west-aligned ridge.
The Myddfai Steep Belt is a geological structure which affects rocks of Silurian and Devonian age in mid Wales. It extends for tens of miles across country from near Carmarthen northeastwards via Mynydd Myddfai, Mynydd Bach Trecastell and Mynydd Epynt to the vicinity of Llangammarch Wells. Within this linear zone, the rock beds have been tilted steeply to the southeast. The folding took place in late Silurian to early Devonian times. This structure gives rise to a series of landscape features along its length, not least the steep northwest-facing scarps of the hills and ranges mentioned above. Indeed, the feature can be seen as a significant lineament in aerial and satellite views of Wales.
The geological structure of Great Britain is complex, resulting as it does from a long and varied geological history spanning more than two billion years. This piece of the Earth's crust has experienced several episodes of mountain building or 'orogenies', each of which has added further complexity to the picture.
The geology of Lancashire in northwest England consists in the main of Carboniferous age rocks but with Triassic sandstones and mudstones at or near the surface of the lowlands bordering the Irish Sea though these are largely obscured by Quaternary deposits.
The Central Wales Lineament is a north–south aligned zone of geological faults and folds which runs for scores of miles through Wales and which gives rise to a number of landscape features. The lineament lies along the axis of the Central Wales Syncline, both following the generally northeast–southwest Caledonide trend though its central section is more north–south aligned.
The geology of West Sussex in southeast England comprises a succession of sedimentary rocks of Cretaceous age overlain in the south by sediments of Palaeogene age. The sequence of strata from both periods consists of a variety of sandstones, mudstones, siltstones and limestones. These sediments were deposited within the Hampshire and Weald basins. Erosion subsequent to large scale but gentle folding associated with the Alpine Orogeny has resulted in the present outcrop pattern across the county, dominated by the north facing chalk scarp of the South Downs. The bedrock is overlain by a suite of Quaternary deposits of varied origin. Parts of both the bedrock and these superficial deposits have been worked for a variety of minerals for use in construction, industry and agriculture.
The Exmoor Group is a late Devonian to early Carboniferous lithostratigraphic group in southwest England whose outcrop extends from Croyde in north Devon east across Exmoor to Minehead in west Somerset. The group comprises the following formations the:
This article describes the geology of Dartmoor National Park in Devon, in south-west England. Dartmoor gained national park status in 1951 but the designated area of 954 km2 (368 sq mi) extends beyond the upland of Dartmoor itself to include much of the surrounding land, particularly in the northeast. The geology of the national park consists of a 625 km2 (241 sq mi) core of granite intruded during the early Permian period into a sequence of sedimentary rocks originating in the Devonian and Carboniferous periods. These rocks were faulted and folded, sometimes, intensely, during the Variscan orogeny. Thermal metamorphism has also taken place around the margins of the granite pluton altering the character of the sedimentary rocks whilst mineral veins were emplaced within the granite. A small outlier of Palaeogene sediments occurs on the eastern boundary of the national park.
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.
References
- ↑ British Geological Survey 1:50,000 map sheets 214, 215, 231 'Merthyr Tydfil', 232 'Abergavenny', 247 'Swansea' & accompanying memoirs
- ↑ Brenchley PJ & Rawson PF (eds) 2006 The Geology of England and Wales (2nd edn), The Geological Society, London (p135)
- ↑ sheets 25 & 31 of 1:50K scale map geological map series of British Geological Survey
- ↑ Cave, R; Hains, B A (2001). Geology of the Country around Montgomery and the Ordovician rocks of the Shelve area (1st ed.). London: BGS; NERC;The Stationery Office. p. 127. ISBN 0118845527.
- ↑ Cossey et al, 2004, British Lower Carboniferous Stratigraphy, Geological Conservation Review Series, no 29, Joint Nature Conservation Committee, Peterborough
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