Mapping Mountains – Significant Name Changes – 30-99m Twmpau and Y Trechol – The Dominant Hills of Wales

Cefn y Coed (SH 667 172) 

There has been a Significant Name Change to a hill that is listed in the 30-99m Twmpau and Y Trechol – The Dominant Hills of Wales, with the summit height, bwlch height and their locations, the drop, dominance and status of the hill derived from LIDAR analysis conducted by Myrddyn Phillips. 

LIDAR image of Cefn y Coed (SH 667 172)

The criteria for the two listings 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, with the word Twmpau being an acronym standing for thirty welsh metre prominences and upward. 

30-99m Twmpau 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 hill is adjoined to the Cadair Idris group of hills, which are situated in the south-western part of North Wales (Region A, Sub-Region A3), and it is positioned with the A493 road to its south-east, and has the town of Dolgellau towards the east.

The hill appeared in the original Welsh 30-99m P30 list on Geoff Crowder’s v-g.me website, under the transposed name of Coed-y-garth, which is a prominent name that appears to the south-west of the summit of this hill on the contemporary Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer map.

Coed-y-garth

90c

SH666172

124

23

Two points of same height

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.  My preference was to use farm names and put Pen, Bryn or Moel in front of them or as in this instance transpose a prominent name that appears on the Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer map and use it for that of the hill.  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. 

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 185 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 Cefngoed in the apportionments, with the details on the Tithe map appearing in the parish of Dolgellau and in the county named as Merioneth. 

Extract from the apportionments

The Ordnance Survey One-Inch ‘Old Series’ map hosted on the website accessing the Tithe maps gives two prominent names for the wooded area taking in this hill; Coed y Garth to the south-west and Cefn-y-coed close to the summit of this hill.  With the Tithe map giving the land boundary between each and which is still portrayed on contemporary Ordnance Survey maps. 

Extract from the Ordnance Survey One-Inch Old Series map hosted on the Tithe website

Therefore, the name this hill is now listed by in the 30-99m Twmpau and Y Trechol – The Dominant Hills of Wales is Cefn y Coed, and this was derived from the Tithe map. 

 

The full details for the hill are:

Group:  Cadair Idris

Name:  Cefn y Coed

Previously Listed Name:  Coed-y-garth 

OS 1:50,000 map:  124

Summit Height:  89.0m (LIDAR) 

Summit Grid Reference:  SH 66751 17241 (LIDAR)               

Bwlch Height:  26.7m (LIDAR) 

Bwlch Grid Reference:  SH 67045 17182 (LIDAR) 

Drop:  62.3m (LIDAR) 

Dominance:  69.98% (LIDAR) 

 

Myrddyn Phillips (May 2024)

 

  

Mapping Mountains – Summit Relocations – 30-99m Twmpau and Y Trechol – The Dominant Hills of Wales

Cefn y Coed (SH 667 172) 

There has been a Summit Relocation to a hill that is listed in the 30-99m Twmpau and Y Trechol – The Dominant Hills of Wales, with the summit height, bwlch height and their locations, the drop, dominance and status of the hill derived from LIDAR analysis conducted by Myrddyn Phillips. 

LIDAR image of Cefn y Coed (SH 667 172)

The criteria for the two listings that this summit relocation 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, with the word Twmpau being an acronym standing for thirty welsh metre prominences and upward. 

30-99m Twmpau 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 now listed by is Cefn y Coed and this was derived from the Tithe map, and it is adjoined to the Cadair Idris group of hills, which are situated in the south-western part of North Wales (Region A, Sub-Region A3), and it is positioned with the A493 road to its south-east, and has the town of Dolgellau towards the east.

When the original 30-99m height band of Welsh P30 hills were published on Geoff Crowder’s v-g.me website, this hill was included in the main P30 list with a non-interpolated summit height of c 90m positioned at SH 666 172, with an accompanying note stating; Two points of same height, a reference to the two uppermost 90m ring contours that appear on the contemporary Ordnance Survey 1:25,000 Explorer map. 

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

When 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 64m of drop, based on an estimated c 91m summit height positioned at SH 66668 17206 and an estimated c 27m bwlch height, based on interpolation of 10m contouring between 20m – 30m, with these values giving this hill 70.33% dominance.

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.

LIDAR analysis gives the highest ground on this hill as 89.0m positioned at SH 66751 17241, and this comes within the parameters of the Summit Relocations used within this page heading, these parameters are:

The term Summit Relocations applies when the high point of the hill is found to be positioned; in a different field, to a different feature such as in a conifer plantation,  within a different map contour, to a different point where a number of potential summit positions are within close proximity, when natural ground or the natural and intact summit of a hill is confirmed compared to a higher point such as a raised field boundary or covered reservoir that is judged to be a relatively recent man-made construct, or a relocation of approximately 100 metres or more in distance from either the position of a map spot height or from where the summit of the hill was previously thought to exist.

Therefore, the height produced by LIDAR analysis to the highest ground on this hill is 89.0m and is positioned at SH 66751 17241, this position is not given a spot height on the contemporary Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer map, and is approximately 83 metres north-eastward and placed in a different map contour compared to where the previously listed summit is positioned. 

 

The full details for the hill are:

Group:  Cadair Idris 

Name:  Cefn y Coed 

OS 1:50,000 map:  124

Summit Height:  89.0m (LIDAR) 

Summit Grid Reference (New Position):  SH 66751 17241 (LIDAR)               

Bwlch Height:  26.7m (LIDAR) 

Bwlch Grid Reference:  SH 67045 17182 (LIDAR) 

Drop:  62.3m (LIDAR) 

Dominance:  69.98% (LIDAR) 

 

Myrddyn Phillips (May 2024)

 

  

Mapping Mountains – Significant Height Revisions – 30-99m Twmpau and Y Trechol – The Dominant Hills of Wales

 

Cefn y Coed (SH 667 172) 

There has been a Significant Height Revision to a hill that is listed in the 30-99m Twmpau and Y Trechol – The Dominant Hills of Wales, with the summit height, bwlch height and their locations, the drop, dominance and status of the hill derived from LIDAR analysis conducted by Myrddyn Phillips. 

LIDAR image of Cefn y Coed (SH 667 172)

The criteria for the two listings that this height revision 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, with the word Twmpau being an acronym standing for thirty welsh metre prominences and upward. 

30-99m Twmpau 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 now listed by is Cefn y Coed and this was derived from the Tithe map, and it is adjoined to the Cadair Idris group of hills, which are situated in the south-western part of North Wales (Region A, Sub-Region A3), and it is positioned with the A493 road to its south-east, and has the town of Dolgellau towards the east.

When the original 30-99m height band of Welsh P30 hills were published on Geoff Crowder’s v-g.me website, this hill was included in the main P30 list with a non-interpolated summit height of c 90m positioned at SH 666 172, with an accompanying note stating; Two points of same height, a reference to the two uppermost 90m ring contours that appear on the contemporary Ordnance Survey 1:25,000 Explorer map. 

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

When 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 64m of drop, based on an estimated c 91m summit height positioned at SH 66668 17206 and an estimated c 27m bwlch height, based on interpolation of 10m contouring between 20m – 30m, with these values giving this hill 70.33% dominance.

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.

The summit height produced by LIDAR analysis is 89.0m and is positioned at SH 66751 17241, 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 or Harvey 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 to the data produced by the Trimble or by LIDAR analysis.

Therefore, the new listed summit height of this hill is 89.0m and this was derived from LIDAR analysis, this is 2.0m lower than the previously listed summit height of c 90m, which was based on interpolation of the uppermost 90m 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:  Cadair Idris 

Name:  Cefn y Coed 

OS 1:50,000 map:  124

Summit Height (New Height):  89.0m (LIDAR) 

Summit Grid Reference:  SH 66751 17241 (LIDAR)               

Bwlch Height:  26.7m (LIDAR) 

Bwlch Grid Reference:  SH 67045 17182 (LIDAR) 

Drop:  62.3m (LIDAR) 

Dominance:  69.98% (LIDAR) 

 

Myrddyn Phillips (May 2024)