Garneddwen

The Afon Deri (sometimes known as the Afon Corris) is a river in Mid Wales. It flows from the eastern flank of Mynydd Ty-Glas down to Corris, where it joins the Afon Dulas that flows south to the Afon Dyfi.The river passes through the village of Corris Uchaf and its lower reaches pass through the richest area of slate quarrying in Mid Wales. The Braichgoch, Abercorris and Abercwmeiddaw quarries are to be found beside the Afon Deri.

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.

Cwm Hengae is a valley that runs roughly north-west from the village of Aberllefenni in Wales. The Afon Llefenni river runs along the valley and several slate quarries occupy the valley sides. The Roman road Sarn Helen ran along the valley, connecting Aberllefenni with Dolgellau.

The Narrow Vein Mudstone Formation (commonly known as the Narrow Vein) is an Ordovician lithostratigraphic group (a sequence of rock strata) in Mid Wales. The rock of the formation is silty, homogeneous 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.

Corris is a village in the county of Gwynedd, Wales, about 4.5 miles (7 km) north of the town of Machynlleth. The village lies on the west bank of the Afon Dulas (which here forms the boundary with Powys), around that river's confluence with the Afon Deri. Its railway station is the headquarters and museum of the Corris Railway, a preserved narrow gauge railway. The area has a community council. The community council system replaced the former parish council system and tackles local issues, acts as a contact point between local government and residents for information and resources on various issues. The community elects one member to represent Corris/Mawddwy ward of Gwynedd Council. Besides Corris, the ward covers Mawddwy community to the north-east.

Aberllefenni quarry is the collective name of three slate quarries, Foel Grochan, Hen Gloddfa (also known as Hen Chwarel) 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.

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 Broad Vein Mudstone Formation (commonly known as the Broad Vein, historically known as the Red Vein 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.

The Abercorris quarry (also known as Cwmodyn quarry) was a slate quarry worked between the mid-1840s and the early 1950s. It was located at Corris Uchaf about 5 miles 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. It worked the Narrow Vein.

Cambergi quarry (also known as Wenallt quarry) was a slate quarry in Cwm Hengae, west of Aberllefenni in North Wales. It operated between 1873 and about 1895.

The Corris Railway (Welsh: Rheilffordd Corris) is a narrow gauge preserved railway based in Corris on the border between Merionethshire (now Gwynedd) and Montgomeryshire (now Powys) in Mid-Wales. The line opened in 1859 as a horse tramway, running originally from quays on the River Dyfi at Morben and Derwenlas, skirting the town of Machynlleth and then following the Dulas Valley north to Corris and on to Aberllefenni. Branches served the slate quarries at Corris Uchaf, Aberllefenni, the isolated quarries around Ratgoed and quarries along the length of the Dulas Valley. The railway closed in 1948, but a preservation society was formed in 1966, initially opening a museum; a short section of line between Corris and Maespoeth was re-opened to passengers in 2002. The railway now operates as a tourist attraction. A new steam locomotive was built for the railway, which was delivered in 2005. The two surviving locomotives, plus some of the original rolling stock, are preserved on the nearby Talyllyn Railway. The gauge of the railway is 2 ft 3 in (686 mm) which is unusual, and was shared by only three other public railways in the United Kingdom: the Talyllyn Railway, the short-lived Plynlimon and Hafan Tramway and the Campbeltown and Machrihanish Light Railway.

Mynydd Cambergi or Mynydd Cam-bergi is a mountain in southern Snowdonia, Wales. It is a summit on a long ridge between Mynydd y Waun to the north and Foel Grochan to the east. The mountain forms the north-east side of Cwm Hengae and sits about 0.5 miles (0.80 km) west of the village of Aberangell. Near the summit of the mountain lies the open pit of Cambergi quarry, which was worked from the 1870s to the 1890s.