Pen Allt-mawr

About Pen Allt-mawr

Pen Allt-mawr is a subsidiary summit of Waun Fach and the third highest peak in the Black Mountains, sitting near the end of the more westerly of Waun Fach's two broad southern ridges. It is one of the more recognisable profiles in the range. Pen Twyn Glas lies north along the ridge, Pen Cerrig-calch close to the south.

The stony summit carries a trig point, a large shelter cairn and damaged Bronze Age cairns, with further cairns strung along the western edge of the plateau to the south. A prominent spur a kilometre SSW, Pen Gloch-y-pibwr, is where the stepped Bryniog ridge curves away southward.

Background written from facts in the Wikipedia article on Pen Allt-mawr (CC BY-SA 4.0). Heights, prominence and grid references come from the Database of British & Irish Hills, not from Wikipedia.

Access rights here

General position for Wales — local byelaws, seasonal restrictions and closures can override it. Full details: access rights in Wales · check another location.

Daylight at this summit today

Sunrise

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Sunset

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Daylight

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Civil twilight ends

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Computed astronomically for 51.912, -3.154. Plan your finish with the daylight safety planner.

Finding the summit

The recorded summit point is no feature 30m S of trig point. That distinction matters on broad or flat tops, where the obvious cairn is not always the true high point.

Survey method

Abney level

Record revised

05-Jan-20

Drop measured from

SO 2044 2861 · 616.1 m

Survey notes are field observations recorded in the Database of British & Irish Hills (v18.3, CC BY 4.0) by the hill-surveying community.

Long-distance paths past this hill

2 waymarked long-distance routes run within 2.5 km of the summit — useful if you are linking this hill into a longer walk, or want a made path for the approach.

Route lines © OpenStreetMap contributors (ODbL); distance from the summit computed by OpenFell.

Which hill this one belongs to

Pen Allt-mawr is not counted as an independent hill in its own right. In prominence terms it belongs to Waun Fach (811 m) — the nearest Marilyn you can reach from this summit without first dropping below its key col, 616 m.

Grouping is by prominence alone: a summit belongs to the nearest higher Marilyn it connects to without a deeper intervening col. Over a large massif that can gather hills no one would walk in a single day, and which few would describe as parts of the same mountain — it is a measure of independence, not a suggested route.

Nearest listed peaks