Mapping Mountains – Significant Name Changes – 30-99m Twmpau

Gwales (SM 598 094 & SM 598 093) 

There has been a Significant Name Change that is retrospective to a hill that is listed in the 30-99m Twmpau, with the summit height and its location, the drop and status of the hill derived from detail on maps produced from Ordnance Survey data.                       

Gwales (SM 598 094 & SM 598 093)

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

30-99m Twmpau - Welsh hills at or above 30m and below 100m in height that have 30m minimum drop, with an accompanying sub list entitled the 30-99m Sub-Twmpau, with the criteria for this sub category being all Welsh hills at or above 30m and below 100m in height with 20m or more and below 30m of drop.  The list is authored by Myrddyn Phillips, with the word Twmpau being an acronym standing for thirty welsh metre prominences and upward. 

30-99m Twmpau by Myrddyn Phillips

The hill is adjoined to the Garn Fawr group of hills, which are situated in the south-western part of South Wales (Region B, Sub-Region B1), and it is positioned with the nearest minor road on the mainland to its east, and has the town of Hwlffordd (Haverfordwest) on the mainland towards the east north-east. 

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

When the original 30-99m height band of Welsh P30 hills were published on Geoff Crowder’s v-g.me website, this hill appeared under the transposed name of Grassholm Island, which is a prominent name that appears adjacent to this island on the Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer map.

Grassholm Island

42m

SM598093

157

36

During my early hill listing I thought it appropriate to either invent a name for a hill or use a name that appeared near to the summit of the hill on Ordnance Survey maps of the day, with little consideration for the meaning of the name or the language used and where the name was appropriately applied to.  This is not a practice that I now advocate as with time and inclination place-name data can be improved either by asking local people or by examining historic documents, through this form of research an appropriate name for the hill can usually be found.

The intricacies of language and prioritising one in favour of another for listing a hill is fraught with complication, with originating Cymraeg names being anglicised and also originating English names being cymricised, examples such as these are more common in border country and especially so for anglicised forms.  There is no steadfast rule that fits all, but as a standard a name that has its origins in the Welsh language and where this is substantiated by either historic documentation and/or contemporary usage should be prioritised in favour of a contemporary anglicised or English version of the name.  Likewise, if a name exists where an element of it is in English and if this name applies to a hill that is situated in a Welsh speaking part of Wales it is standard practice to use a full Welsh term for the name.  It is also standard practice to use a Welsh name for a hill if another name exists that has originated in a different language.

Therefore, the name this hill is now listed by in the 30-99m Twmpau is Gwales, and this was derived from various sources including the Dictionary of the Place-Names of Wales by Hywel Wyn Owen and Richard Morgan and published by Gomer Press. 

 

The full details for the hill are:

Group:  Garn Fawr

Name:  Gwales 

Previously Listed Name:  Grassholm Island   

OS 1:50,000 map:  157

Summit Height:  42m (spot height) 

Summit Grid Reference:  SM 59840 09415 & SM 59825 09366 (spot height)               

Bwlch Height:  N/A (sea level) 

Bwlch Grid Reference:  N/A (sea level) 

Drop:  42m (spot height) 

 

Myrddyn Phillips (June 2026)

 

  

Monthly Synopsis

 

Synopsis of all major changes detailed on Mapping Mountains during the last calendar month.  These can include new, confirmation and retrospective changes

 

Hill Reclassifications: 

Llethr Gwaered (SN 795 626) - Pellennig addition

Shadwell Hill (SO 201 865) - Sub-Four addition

Rhos Ffidl (SO 206 854) - Sub-Four addition

 

Significant Height Revisions: 

Craig Ysgafn (SH 659 443) - 600m Twmpau and The Welsh Highlands - Uchafion Cymru

Craig Ysgafn (SH 660 442) - The Welsh Highlands - Uchafion Cymru

Cefn y Coed (SO 211 934) - Y Trichant - The 300m Hills of Wales and Y Trechol - The Dominant Hills of Wales

Summit Relocations: 

Cae Tros Ffordd (SH 797 643) - The Welsh P15s

Foel Fawr (SH 728 392) - The Deweys

Significant Name Changes: 

Tai Isa (SH 780 620) - The Welsh P15s

Cae Tros Ffordd (SH 797 643) - The Welsh P15s

Mapping Mountains – Significant Name Changes – The Welsh P15s

 

Cae Tros Ffordd (SH 797 643) 

There has been a Significant Name Change to a hill that is listed in The Welsh P15s, with the summit height, bwlch height and their locations, the drop and status of the hill derived from LIDAR analysis conducted by Myrddyn Phillips. 

LIDAR image of Cae Tros Ffordd (SH 797 643)

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

The Welsh P15s – Welsh hills with 15m minimum drop, irrespective of their height, with an accompanying sub list entitled the Welsh Sub-P15s, with the criteria for this sub category being all Welsh hills with 14m or more and below 15m of drop.  The list is authored by Myrddyn Phillips, with the Introduction to the list appearing on Mapping Mountains on the 10^th May 2019. 

The Welsh P15s by Myrddyn Phillips

The hill is adjoined to the Mynydd Hiraethog group of hills, which are situated in the northern part of North Wales (Region A, Sub-Region A2), and it is positioned encircled by minor roads with the A470 road farther to its west, and has the town of Llanrwst towards the south.

When the listing that became known as The Welsh P15s was being compiled, this hill was listed under the point (Pt. 129m) notation, with an estimated c 20m of drop, based on the 129m summit spot height that appeared on the Ordnance Survey Vector Map Local hosted on the Geograph website and which was entitled the Interactive Coverage Map and an estimated c 109m bwlch height, based on interpolation of 10m contouring between 100m – 110m. 

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

As the summit of this hill comprises 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 843 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 Cae Tros Ffordd in the apportionments, with the details on the Tithe map appearing in the parish named as Eglwys-fach and in the county named as Caernarfon. 

Extract from the apportionments

Therefore, the name this hill is now listed by in the The Welsh P15s is Cae Tros Ffordd, and this was derived from the Tithe map. 

 

The full details for the hill are: 

Group:  Mynydd Hiraethog 

Name:  Cae Tros Ffordd 

Previously Listed Name:  Pt. 129m 

OS 1:50,000 map:  115

Summit Height:  127.1m (LIDAR)                                                           

Summit Grid Reference:  SH 79756 64305 (LIDAR) 

Bwlch Height:  107.9m (LIDAR) 

Bwlch Grid Reference:  SH 79900 64455 (LIDAR) 

Drop:  19.2m (LIDAR) 

 

Myrddyn Phillips (May 2026)

 

Mapping Mountains – Significant Height Revisions – Y Trichant – The 300m Hills of Wales and Y Trechol – The Dominant Hills of Wales

 

Cefn y Coed (SO 211 934) 

There has been a Significant Height Revision to a hill that is listed in the Y Trichant – The 300m Hills of Wales and the Y Trechol – The Dominant Hills of Wales, with the summit height, bwlch height and their locations, the drop, the dominance and status of the hill derived from a Leica RX1250 survey conducted by Alan Dawson and a subsequent Trimble GeoXH 6000 summit survey and LIDAR bwlch analysis conducted by Myrddyn Phillips. 

Cefn y Coed (SO 211 934)

The criteria for the two listings that this height revision applies to are:

Y Trichant – The 300m Hills of Wales – Welsh hills at or above 300m and below 400m in height that have 30m minimum drop, with an accompanying sub list entitled the Sub-Trichant, with the criteria for this sub category being all Welsh hills at or above 300m and below 400m in height with 20m or more and below 30m of drop.  The list is authored by Myrddyn Phillips with the Introduction to the list and the renaming of it appearing on Mapping Mountains on the 13^th May 2017, and the Introduction to the Mapping Mountains publication of the list appearing on the 1^st January 2022. 

Y Trichant - The 300m Hills of Wales by Myrddyn Phillips

Y Trechol – The Dominant Hills of Wales – Welsh P30 hills whose prominence equal or exceed half that of their absolute height.  With the criteria for Lesser Dominant status being those additional Welsh P30 hills whose prominence is between one third and half that of their absolute height.  The list is authored by Myrddyn Phillips with the Introduction to the start of the Mapping Mountains publication of this list appearing on the 3^rd December 2015, and the list is now available in its entirety on Mapping Mountains in Google Doc format. 

Y Trechol - The Dominant Hills of Wales by Myrddyn Phillips

The name the hill is listed by is Cefn y Coed and this was derived from the Tithe map, the Ordnance Survey One-Inch ‘Old Series’ map and local enquiry, and it is adjoined to the Cilfaesty group of hills, which are situated in the north-eastern part of South Wales (Region B, Sub-Region B2), and it is positioned with a minor road to its north and the A489 road to its south, and has the town of Trefaldwyn (Montgomery) to its north north-east.

When the original 300m height band of Welsh P30 hills were published on Geoff Crowder’s v-g.me website, this hill was listed with a non interpolated summit height of c 355m, based on the uppermost ring contour that appears on the Ordnance Survey 1:25,000 Explorer map. 

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

After the sub list was standardised, and interpolated heights and drop values also included the details for this hill were re-evaluated and it was listed with an estimated c 173m drop, based on an estimated c 356m summit height and an estimated c 183m bwlch height, with both heights based on interpolation of 5m contouring that appears on the Ordnance Survey 1:25,000 Explorer map. 

The Leica RX1250 set-up position at the summit of Cefn y Coed

However, it was not until the survey with the Leica RX1250 and subsequent LIDAR analysis and the survey with the Trimble GeoXH 6000 that the details for this hill could be accurately re-assessed. 

The Trimble GeoXH 6000 gathering data at the summit of Cefn y Coed

The summit height produced by the Leica RX1250 survey is 353.5m positioned at SO 21163 93413 and the summit height produced by the Trimble GeoXH 6000 survey is 353.6m positioned at SO 21164 93411, and this comes within the parameters of the Significant Height Revisions used within this page heading, these parameters are:

The term Significant Height Revisions applies to any listed hill whose interpolated height and Ordnance Survey, Harvey or other interactive map summit spot height has a 2m or more discrepancy when compared to the survey result produced by the Trimble GeoXH 6000 or analysis of data produced via LIDAR.  Also included are hills whose summit map data is missing an uppermost ring contour when compared with the data produced by the Trimble or by LIDAR analysis.

Therefore, the new listed summit height of this hill is 353.6m and this was derived from a Trimble GeoXH 6000 survey, this is 2.4m lower than the previously listed summit height of c 356m, which was based on interpolation of the uppermost ring contour that appears on the contemporary Ordnance Survey 1:25,000 Explorer map.

 

ills of Wales, and are reproduced below@

The full details for the hill are:

Group:  Cilfaesty

Name:  Cefn y Coed

OS 1:50,000 map:  137

Summit Height (New Height):  353.6m (converted to OSGM15, Trimble GeoXH 6000)

Summit Grid Reference:  SO 21164 93411 (Trimble GeoXH 6000)  

Bwlch Height:  184.2m (LIDAR)

Bwlch Grid Reference:  SO 20667 90868 (LIDAR)

Drop:  169.3m (Trimble GeoXH 6000 summit and LIDAR bwlch)

Dominance:  47.89% (Trimble GeoXH 6000 summit and LIDAR bwlch)

 

Myrddyn Phillips (May 2026)

Mapping Mountains – Hill Reclassifications – The Fours – The 400m Hills of England

 

Rhos Ffidl (SO 206 854) – Sub-Four addition

There has been an addition to the listing of the The Fours – The 400m Hills of England, with the summit height, col height and their locations, the drop and status of the hill derived from LIDAR analysis conducted by Myrddyn Phillips. 

LIDAR image of Rhos Ffidl (SO 206 854)

The criteria for the list that this addition applies to are:

The Fours – The 400m Hills of England - English hills at or above 400m and below 500m in height that have 30m minimum drop, accompanying the main list is a sub list entitled the Sub-Fours, the criteria for which are all English hills at or above 400m and below 500m in height that have 15m or more and below 30m of drop.  The list is co-authored by Myrddyn Phillips and Aled Williams and is available to download in Google Doc format from the Mapping Mountains site.

The Fours - The 400m Hills of England by Myrddyn Phillips and Aled Williams

The name the hill is listed by is Rhos Ffidl, and it is adjoined to the Cilfaesty group of hills, which are situated adjoined to the Welsh border, and it is positioned with minor roads to its north-east and north-west, and the B4368 road towards the south, and has the village of Ceri (Kerry) towards the north-west.

When the Introduction to the first group of hills for the updated and revised listing of the The Fours – The 400m Hills of England was published by Mapping Mountains on the 10^th September 2022, it was announced that the accompanying sub lists were being revised with the two 390m categories dispensed with and the criteria and name of the 400m Sub-Fours revised.  The one accompanying sub list is now named the Sub-Fours with its criteria being all English hills 400m and above and below 500m in height that have 15m and more and below 30m of drop. 

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

Prior to this revision this hill was listed with an estimated c 14m of drop, based on the 422m summit spot height that appears on the Ordnance Survey 1:50,000 Landranger map and an estimated c 408m col height, based on interpolation of 5m contouring between 405m – 410m. 

Extract from the Ordnance Survey 1:50,000 Landranger map

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.

Therefore, the addition of this hill to Sub-Four status is due to LIDAR analysis, resulting in a 422.7m summit height and a 407.1m col height, with these values giving this hill 15.7m of drop, which is sufficient for it to be classified as a Sub-Four. 

 

The full details for the hill are:

Group:  Cilfaesty

Name:  Rhos Ffidl

OS 1:50,000 map:  137

Summit Height:  422.7m (LIDAR)

Summit Grid Reference:  SO 20652 85426 (LIDAR)

Col Height:  407.1m (LIDAR)

Col Grid Reference:  SO 20510 85766 (LIDAR)

Drop:  15.7m (LIDAR)

 

For the additions, deletions and reclassifications to The Fours – The 400m Hills of England reported on Mapping Mountains since the December 2013 publication of the 1^st edition of this list by Europeaklist please consult the following Change Registers:

 

The Fours

 

Sub-Fours

 

Myrddyn Phillips and Aled Williams (May 2026)