Mynydd Hendre-ddu or Mynydd Hendreddu is a

mountain A mountain is an elevated portion of the Earth's crust, generally with steep sides that show significant exposed bedrock. Although definitions vary, a mountain may differ from a plateau in having a limited Summit (topography), summit area, and ...

in southern

Snowdonia Snowdonia or Eryri (), is a mountainous region in northwestern Wales and a national park of in area. It was the first to be designated of the three national parks in Wales, in 1951. Name and extent It was a commonly held belief that the nam ...

, Wales. It is one of a line of mountains running from

Mynydd Dolgoed Mynydd Dolgoed or Craig Portas is a mountain in southern Snowdonia, Wales. It is a long ridge running from a low summit between the valleys of the Afon Angell and the Nant Ceiswyn, north east to the cliff of Craig Portas above Dinas Mawddwy. The ...

in the north, through

Mynydd Llwydiarth Mynydd Llwydiarth is a mountain in southern Snowdonia, Wales. It is a long ridge running from a low summit to the south of Mynydd Dolgoed, running south-west to Mynydd Cymerau. Nant Llwydiarth The Nant Llwydiarth is a small river in Mid Wales ...

to Mynydd Hendre-ddu and on to Mynydd y Foel, Y Grug, Mynydd Tri-Arglwyd and Mynydd Gwyn to the south of the village of

Aberangell Aberangell () is a village in Gwynedd, Wales. Geography Aberangell stands at the confluence of the Afon Angell and the Afon Dyfi, and lies within Dinas Mawddwy community. On the north side of the village, the long ridge of Pen y Clipau runs d ...

. It forms the watershed between

Nant Llwydiarth The Nant Llwydiarth is a small river in Mid Wales. It flows from the southern flank of Mynydd Hendre-ddu down to Pont Cymerau, north-east of Aberllefenni. Here it joins the Nant Ceiswyn to form the Afon Dulas The Afon Dulas, or North Dulas, ...

, which flows to the south-west and into the

Afon Dulas The Afon Dulas, or North Dulas, is a river forming the border between Merionethshire/Gwynedd and Montgomeryshire/Powys in Wales. Another river called Afon Dulas joins the Dyfi from the south, upstream of its confluence with the North Dulas: loca ...

, and streams flowing into

Afon Angell The Afon Angell is a river in Gwynedd, Mid Wales. The river flows eastwards from its source on the eastern flank of Mynydd Dolgoed, joining the Afon Dyfi at the small village of Aberangell. The river was known for its salmon and trout fishing ...

to the north, which flow east into the

River Dyfi The River Dyfi ( cy, Afon Dyfi; ), also known as the River Dovey (; ), is an approximately long river in Wales. Its large estuary forms the boundary between the counties of Gwynedd and Ceredigion, and its lower reaches have historically been c ...

The summit is notable for a set of parallel ridges about across and long that run across it. On the northern slope of the mountain lay the Hendre Ddu slate quarry which was connected to Aberangell by the

Hendre-Ddu Tramway The Hendre-Ddu Tramway was a narrow gauge industrial railway built in 1874 in Mid-Wales to connect the Hendre-Ddu slate quarry to Aberangell station on the Mawddwy Railway. It consisted of a main line long and several branch lines and spurs ...

. Mynydd Hendre-ddu is one of the Dyfi hills.

References

{{coord, 52.69279861, N, 3.77413743, W, region:GB_type:mountain, display=title Mountains and hills of Snowdonia Landmarks in Wales Mountains and hills of Gwynedd Mawddwy Dyfi Hills