Cwm Hengae is a

valley A valley is an elongated low area often running between Hill, hills or Mountain, mountains, which will typically contain a river or stream running from one end to the other. Most valleys are formed by erosion of the land surface by rivers ...

that runs roughly north-west from the village of

Aberllefenni 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. Government The village has a community council. The ...

in Wales. The

Afon Llefenni This is a list of rivers of Wales, organised geographically. It is taken anti-clockwise from the Dee Estuary to the M48 Bridge that separates the estuary of the River Wye from the River Severn. Tributaries are listed down the page in an upstrea ...

river runs along the valley and several slate quarries occupy the valley sides. The

Roman road Roman roads ( la, viae Romanae ; singular: ; meaning "Roman way") were physical infrastructure vital to the maintenance and development of the Roman state, and were built from about 300 BC through the expansion and consolidation of the Roman Re ...

Sarn Helen Sarn Helen refers to several stretches of Roman road in Wales. The route, which follows a meandering course through central Wales, connects Aberconwy in the north with Carmarthen in the west. Despite its length, academic debate continues as t ...

ran along the valley, connecting Aberllefenni with

Dolgellau Dolgellau () is a town and community in Gwynedd, north-west Wales, lying on the River Wnion, a tributary of the River Mawddach. It was the traditional county town of the historic county of Merionethshire ( cy, Meirionnydd, Sir Feirionnydd) un ...

Hengae House

At the point where the Nant Bychan joins the Afon Llefenni, about a third of the way from Aberllefenni to the head of the valley is Hengae House. This was the home of the Anwyl family during the 19th century.

Slate quarrying

The major industry in Cwm Hengae was slate quarrying. Near the eastern end of the valley lie the three quarries that make up the

Aberllefenni Quarry 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 contin ...

. On the south side of the valley are the Hen Gloddfa and Ceunant Du quarries, while on the north is Foel Grochan, named after the mountain it mined. These may have started working as early as the 14th century; the earliest confirmed date of operating is 1500 when the local house Plas Aberllefenni was roofed in slates from the mine. The mines were in continuous operation until 2002, making them the longest continually working slate mines in the world. Further west, on the flank of Mynydd Cambergi lies

Cambergi quarry 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. History The Cambergi Slate Company Limited was formed in 1873 to work the quarry, ...

, a less successful endeavor. On the south side of the valley, opposite Cambergi is the even less successful Hengae quarry. There are a few much smaller trial workings towards the head of the valley.

References

{{reflist Aberllefenni Valleys of Gwynedd