Broad Vein Mudstone Formation Stratigraphic range: Hirnantian Age | |
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The Abercwmeiddaw quarry in Corris Uchaf which quarried the Broad Vein | |
Type | Group |
Unit of | Abercorris Group |
Underlies | Narrow Vein Mudstone Formation |
Overlies | Nod Glas Formation |
Lithology | |
Primary | Mudstone |
Other | Slate |
Location | |
Coordinates | 52°39′48″N3°50′43″W / 52.6632°N 3.8453°W Coordinates: 52°39′48″N3°50′43″W / 52.6632°N 3.8453°W |
Region | Mid Wales |
Country | Wales |
The Broad Vein Mudstone Formation (commonly known as the Broad Vein, historically known as the Red Vein [1] and in Welsh as Y Faen Goch) is an Ordovician lithostratigraphic group (a sequence of rock strata) in Mid Wales. The rock of the formation is silty mudstone, intensely bioturbated in places. It varies in colour from a pale to a medium blue. This formation has been commercially quarried as slate in several locations along its length. The formation is between 400 metres (1,300 ft) and 560 metres (1,840 ft) thick and runs from Dinas Mawddwy south-west to Cardigan Bay at Tywyn. [2]
The formation is exposed in a number of locations in Mid Wales where glacial valleys cut across it. It is especially visible in the quarries along its length.
The Broad Vein is one of the two major slate veins in Mid Wales that were commercially quarried. Broad Vein rock is generally dense, with few natural joints, so most of the commercial use was for slab and products such as mantlepieces, cisterns and (later) electrical switchboards. Production of roofing slates was relatively rare in Broad Vein quarries. [3]
The Broad Vein was quarried in the following locations:
The Corris Railway is a narrow gauge preserved railway based in Corris on the border between Merionethshire and Montgomeryshire in Mid-Wales.
Aberllefenni quarry is the collective name of three slate quarries, Foel Grochan, Hen Gloddfa and Ceunant Ddu, located in Cwm Hengae, just to the west of Aberllefenni, Gwynedd, North Wales. It was the longest continually operated slate mine in the world until its closure in 2003. Foel Grochan is the quarry on the north side of the valley, facing Ceunant Ddu and Hen Gloddfa on the south; all three were worked as a single concern throughout their history. Rock was mainly extracted underground, though all three quarries had open pits as well.
Aberllefenni is a village in the south of Gwynedd, Wales. It lies in the historic county of Merionethshire/Sir Feirionnydd, in the valley of the Afon Dulas, and in the community of Corris.
Ratgoed quarry was the northernmost of the slate quarries served by the Corris Railway. It is one mile north of Aberllefenni in Gwynedd, Mid Wales, on the western side of Mynydd Llwydiarth. The quarry primarily worked the Narrow Vein, though it also produced some Broad Vein slates.
Bryn Eglwys quarry was a slate quarry and mine near Abergynolwyn, in Gwynedd, Wales. More than 300 men worked at the site, making it the principal employer in the area. Two veins of slate, known as the Broad Vein and the Narrow Vein, were worked. The geology continues eastwards towards Corris and Dinas Mawddwy, and westwards towards Tywyn. It was one of many quarries in Mid Wales that worked these veins.
The Hendre-Ddu Tramway was a 2 ft narrow gauge industrial railway built in 1867 in Mid-Wales to connect the Hendre-Ddu slate quarry to Aberangell station on the Mawddwy Railway. It consisted of a main line 3 1⁄2 miles (5.6 km) long and several branch lines and spurs serving other quarries, local farms and the timber industry.
The Mawddwy Railway was a rural line in the Dyfi Valley in mid-Wales that connected Dinas Mawddwy with a junction at Cemmaes Road railway station on the Newtown and Machynlleth Railway section of the Cambrian Railways.
Garneddwen is a hamlet in the south of the county of Gwynedd, Wales. It lies in the historic county of Merionethshire/Sir Feirionnydd, in the valley of the Afon Dulas.
The Dyfi hills are a range situated in the southernmost area of Snowdonia, bounded by the River Dyfi on the east and south sides, by the Afon Dulas on the west and the Afon Cerist to the north. They lie to the west of the Aran Fawddwy range, north-east of the Tarren y Gesail range and are a subgroup of the Cadair Idris group.
The Ratgoed Tramway was a 2 ft 3 in gauge horse-worked tramway that connected the remote Ratgoed Quarry with the Corris Railway at Aberllefenni. It was 1.75 miles (2.82 km) long.
The Nant Ceiswyn is a small river in Mid Wales. It flows from the northern flank of Mynydd Dolgoed down to Pont Cymerau, north-east of Aberllefenni. Here it joins the Nant Llwydiarth to form the Afon Dulas that flows south to the Afon Dyfi. There was an ancient bridge at Pont Cymerau.
Cymerau quarry was a slate quarry served by the Ratgoed Tramway, a horse-worked section of the Corris Railway. It is located about half a mile north of Aberllefenni in Merioneth, North Wales, on the eastern side of the isolated Cwm Ceiswyn. It worked the Narrow Vein, the highest-quality slate vein in the Abercorris Group.
The Abercwmeiddaw quarry was a slate quarry that operated between the 1840s and 1938. It was located at Corris Uchaf about 5 miles (8.0 km) north of Machynlleth, in Gwynedd, north-west Wales. The quarry was connected to the Corris Railway via the Upper Corris Tramway which carried its products to the Cambrian Railways at Machynlleth for distribution.
The Narrow Vein Mudstone Formation is an Ordovician lithostratigraphic group in Mid Wales. The rock of the formation is silty, homogenous or finely-laminated mudstone. It generally a medium blue colour. This formation has been commercially quarried as slate in several locations along its length. The formation is between 400 metres (1,300 ft) and 560 metres (1,840 ft) thick and runs from Dinas Mawddwy south-west to Cardigan Bay at Tywyn.
The Ceiswyn Formation is an Ordovician lithostratigraphic group in Mid Wales. The rock of the formation is made up of interleaved beds of silty mudstones and siltstones with some sandstones and tuffs also present in small amounts. The formation runs diagonally across Mid Wales from close by Bala Lake to Cardigan Bay near Tywyn.
The Nod Glas Formation is an Ordovician lithostratigraphic group in Mid Wales. The rock of the formation is made up of pyritous, graptolitic mudstone that is generally black in colour. It weathers to a soft, very well cleaved and coal-like material. The formation runs from Conwy in the north, down to Cardigan Bay in the area around Aberdyfi and Tywyn, though it is not a continuous over this area.
The Garnedd-Wen Formation is an Ordovician lithostratigraphic group in Mid Wales. The rock of the formation is a mixture of mudstones, siltstones, fine- to coarse-grained sandstones, greywackes and conglomerates. The formation extends from Dinas Mawddwy in the north-east to Tywyn in the south-west.
The Deeside and Moelfferna quarries were neighbouring slate quarries, near Glyndyfrdwy in North Wales. They were both operated by the same company throughout their history, and were both connected by the Deeside Tramway to the Llangollen and Corwen Railway.
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.
Dolgoch slate quarry was a slate quarry in Mid Wales, approximately halfway between Bryn-crug and Abergynolwyn. The quarry was named after a nearby stream, the Nant Dolgoch. 'Dol goch' is Welsh for 'red meadow'.