Mapping Mountains – Significant Name Changes – 100m Twmpau

Pedwar Erw (SS 864 837)

There has been a Significant Name Change to a hill that is now listed in the 100m Twmpau, with the summit height, bwlch height and their locations, the drop and status of the hill confirmed by LIDAR analysis conducted by Myrddyn Phillips.

LIDAR image of Pedwar Erw

The criteria for the list that this name change applies to are:

100m Twmpau - Welsh hills at or above 100m and below 200m in height with 30m minimum drop, with an accompanying sub list entitled the 100m Sub-Twmpau with the criteria for this sub category being all Welsh hills at or above 100m and below 200m in height with 20m or more and below 30m of drop, with the word Twmpau being an acronym standing for thirty welsh metre prominences and upward.

The hill is adjoined to the Cymoedd Morgannwg group of hills, which are situated in the central part of South Wales (Region C, Sub-Region C2), and it forms a part of landscaped ground that once made up the Margam opencast mine, and is encircled by minor roads to its north, west and east and has the B4281 road and the small communities of Cefn Cribwr and Kenfig Hill towards its south.

This hill did not appear in the original 100m height band of Welsh P30 hills when they were published on Geoff Crowder’s v-g.me website as contemporary Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer maps of the day showed the opencast mine without any ring contours of note.

Extract from the Ordnance Survey 1:25,000 Explorer map

This area was re-examined when the OS Maps website became available online.  This is the replacement for OS Get-a-map and has contours at 5m intervals and for the majority of land comprising old mine workings it shows present day contours, as opposed to the blank space showed on the counterparts of the 1:50,000 Landranger and 1:25,000 Explorer maps.

However, it was not until LIDAR became available that the details for this hill could be accurately re-assessed.  The LIDAR (Light Detection & Ranging) technique produced highly accurate height data that is now freely available for much of England and Wales. 

Prior to OS Maps and LIDAR analysis this hill was not classified as it had not appeared in any known listing of hills.  Therefore, although there is no change in this hill’s listed name it is worth categorising under the heading of Significant Name Changes as the name this hill is now listed by comes from the Tithe map.

As the ground that once made up the summit of this hill comprised bounded land the details for it were examined on the Tithe map.  The term Tithe map is generally given to a map of a Welsh or English parish or township and which was prepared after the 1836 Tithe Commutation Act.  This act allowed tithes to be paid in cash rather than goods.  The Tithe maps gave names of owners and occupiers of land in each parish and importantly for place-name research they also included the name of enclosed land.  This enclosed land is usually based on a field system, however not every field is given a name, but many are and especially so in Wales.

Extract from the Tithe map

The enclosed land where the summit of this hill is situated is given the number 467 on the Tithe map, this can be cross referenced against the apportionments; it is these apportionments that give the name of the owner or occupier of the land as well as the name of the land.  The land where the summit of this hill is situated is named as Pedair [sic] Erw in the apportionments, with the details on the Tithe map appearing in the parish of Lalestone and in the county named as Glamorgan.

Extract from the apportionments

After examining the Tithe map I made local enquiries and contacted Randall Clatworthy who is now aged 79 and was born just to the east of where this hill is situated in Ffordd y Gyfraith and subsequently lived at Cefn Parc which is just to the north of this hill.  Randall now lives in Cefn Cribwr to the south of this hill and told me that this and its adjacent hill are known collectively as the Opencast Mountains.  However, for historic purposes the Tithe name of Pedwar Erw is being prioritised.

Therefore, the name this hill is now listed by in the 100m Twmpau is Pedwar Erw, and this was derived from the Tithe map.

The full details for the hill are:

Group:  Cymoedd Morgannwg

Name:  Pedwar Erw

Previously Listed Name:  previously not listed 

OS 1:50,000 map:  170

Summit Height:  131.0m (LIDAR)

Summit Grid Reference:  SS 86413 83767 (LIDAR)

Bwlch Height:  98.4m (LIDAR)

Bwlch Grid Reference:  SS 86635 84031 (LIDAR)

Drop:  32.5m (LIDAR)

Myrddyn Phillips (May 2019)