The Glamorgan-Gwent Archaeological Trust
Historic Environment Record

The following information has been provided under the terms and conditions of access as detailed on GGAT’s website  Copyright is reserved on all data supplied by the GGAT HER Charitable Trust. All output resulting from the use of the data must acknowledge the source as follows:-
Derived from information held by the GGAT HER Charitable Trust copyright.

The data below is intended to be used for information and research only and is not for use as part of a commercial project.  If you wish to use information derived from material held by the GGAT HER Charitable Trust for publication in printed or multimedia form or to compile resources for commercial use, prior permission must be obtained in writing. For further information or to arrange a visit to the Trust please send an enquiry form to


Primary Reference Number (PRN) : 00559m
Trust : Glamorgan Gwent
Community : Merthyr Vale
Unitary authority : Merthyr Tydfil
NGR : ST0632598923
Site Type (preferred type first) : Bronze Age Cairn
Status : Scheduled Monument

Summary :
A low mound with traces of a kerb on the W side and a cist in the middle. The mound is well marked on the N side as an earthwork but less so on the other sides. It consists of a slightly raised rim and a raised centre with a more depressed area in betw

Description :
A low mound with traces of a kerb on the W side and a cist in the middle. The mound is well marked on the N side as an earthwork but less so on the other sides. It consists of a slightly raised rim and a raised centre with a more depressed area in between. It is not possible to determine without excavation whether this is a ring cairn with internal structures, or a badly robbed ordinary cairn. The possible kerb consists of four stones (up to 0.9m across) of which the two middle ones are on the line of the outer side of the rim and therefore probably in situ; the two end stones look as though they have been displaced outwards, especially the N one. The cist is represented by a slit-like hole measuring 2.0m N-S x 0.3m, the E and W sides of which are lined by slabs; only the W side can be clearly seen, and here the lining is a single slab not quite as long as the hole.
In a clearing in forestry at the top of a hill, with a trig point on it and a radio mast immediately to its NE. A N-S path crosses the mound and has eroded slightly into it. Dimensions: Diameter 18.9m, height c0.8m max
(1953) A turf covered mound situated on the highest point in the vicinity,18.8m diameter and 1.1m high, with many stones exposed, and showing no traces of a surrounding ditch or retaining stones. In the centre of the mound is an exposed cist consisting of two flat stones on edge and parallel to each other, 0.5m apart and orientated N-S. The stones are 1.7m long, 0.1 and 0.2m thick, and protruding from the inner level of th cist some 0.4m, the cist being parttially filled with small stones, and centred in a hollow, probabaly the result of excavations. There are no signs of end stones or a capstone. The mound is surmounted by an OS trig pillar. (Source 02)
(1961/1976) A ring-cairn 19.2m in overall diameter on the summit of a hill. A turf-covered ring-bank 3.7m wide and 0.4m high. Of a central cist aligned NNW-SSE only two slabs are now visible , measuring 1.9x0.2m and 1.5x0.1m, at the WSW and ENE respectively, leaning together to less than 0.3m at the top, but probably 0.9m apart at the bottom; their height is uncertain. No capstone survives. An OS pillar stands on the bank at the SE. (Source 01)
(1972) Twynbrynbychan is a ring-cairn similar to others where a large central cist is suitable for an extended inhumation. The type sites for Ring-cairns are Penmaenmawr and Twyn Bryn Glas. (Lynch 1972, quoted by Source 03)
(1981) The only physical evidence of a ring cairn is the suggestion of a bank less than 0.1m in height internally on the N and E of the cairn. On the other hand the disturbed but clearly raised interior is more indicative of a platform cairn. (Source 03)
(1985) The cairn is situated on the very top of the mountain, with panoramic views all round. It is circular, with a diameter of 18m, and a height of 0.75m. Some large kerb stones are showing around the edge, and on the NW side some large flat slabs are exposed. There is a triangulation station in the middle, and to the NW of it a stone cist is exposed, consisting of two upright slabs of stone, c1.5m long lying parallel, about 0.5m apart. Nettles are growing in the whole between them. (Source 04)
GGAT 72 Prehistoric Funerary and Ritual Sites Project

Sources :
03/MM Record Card/OS//1986/ST 09 NE 1/;
01/PM List/RCAHM//1976/Glam Invent/No.385;
02/MM Record Card/OS//1957/ST 09 NE 1/;
04/MM Desc Text/CADW/Whittle E/1985/AM 107/
PM Desc Text/Evans EM/2000/GGAT 72 Prehistoric Funerary and Ritual Sites Project
pm desc text/Forest Enterprise/1999/Welsh Heritage Assets Project - Contract 14
07/Desc Text/Cadw/ Full Management Report/2007/ Copy in further information file

Events :

Related PRNs : 94651

Compiled date : 01-07-1977

March 23, 2019, 6:10 am - HTML file produced from GGAT HER Charitable Trust Ltd. Heathfield House, Heathfield, Swansea SA1 Tel. 01792 655208; Fax 01792 474469 website:  email: Registered Charity no. 505609
Data supplied by in partnership with Local Authorities, Cadw and the partners of ENDEX © GGAT HER Charitable Trust, 2019 (and in part © Crown, 2019).