Mapping Mountains – Significant Name Changes – 200m Twmpau

 

Cefn Bwlch Cennant (SN 802 424) 

There has been a Significant Name Change to a hill that is listed in the 200m Twmpau, 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 Cefn Bwlch Cennant (SN 802 424)

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

200m Twmpau - Welsh hills at or above 200m and below 300m in height with 30m minimum drop, with an accompanying sub list entitled the 200m Sub-Twmpau with the criteria for this sub category being all Welsh hills at or above 200m and below 300m 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 200m Twmpau by Myrddyn Phillips

The hill is adjoined to the Drygarn Fawr group of hills, which are situated in the central part of the South Wales Region (Region B, Sub-Region B1), and it is positioned encircled by minor roads, with the A483 road farther to its south-east, and has the town of Llanymddyfri (Llandovery) towards the south south-west. 

The hill appeared in the original Welsh 200m P30 list on Geoff Crowder’s v-g.me website, under the invented and transposed name of Bryn y Bwlch-Cynnant, with an accompanying note stating; Name from buildings to the North-West.

Bryn y Bwlch-Cynnant

280c

SN802424

147/160

187

Name from buildings to the North-West

 

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 the name of a farm and prefix it with the words Bryn y.  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 623 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 Cefn Bwlch Cennant in the apportionments, with the details on the Tithe map appearing in the parish of Llanfair-ar-y-bryn and in the county named as Carmarthenshire. 

Extract from the apportionments

Therefore, the name this hill is now listed by in the 200m Twmpau is Cefn Bwlch Cennant, and this was derived from the Tithe map. 

 

The full details for the hill are:

Group:  Drygarn Fawr

Name:  Cefn Bwlch Cennant

Previously Listed Name:  Bryn y Bwlch-Cynnant   

OS 1:50,000 map:  147, 160

Summit Height:  281.2m (LIDAR) 

Summit Grid Reference:  SN 80249 42439 (LIDAR) 

Bwlch Height:  250.55m (LIDAR) 

Bwlch Grid Reference:  SN 80310 42683 (LIDAR) 

Drop:  30.6m (LIDAR) 

 

Myrddyn Phillips (January 2022)

 

 

 

 

 

 

Mapping Mountains – Summit Relocations – 200m Twmpau

 

Cefn Bwlch Cennant (SN 802 424) 

There has been a Summit Relocation to a hill that is listed in the 200m Twmpau, 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 Cefn Bwlch Cennant (SN 802 424)

The criteria for the list that this summit relocation applies to are: 

200m Twmpau – Welsh hills at or above 200m and below 300m in height that have 30m minimum drop, with an accompanying sub list entitled the 200m Sub-Twmpau with the criteria for this sub category being all Welsh hills at or above 200m and below 300m 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 200m Twmpau by Myrddyn Phillips

The name the hill is listed by is Cefn Bwlch Cennant and this was derived from the Tithe map, and it is adjoined to the Drygarn Fawr group of hills, which are situated in the central part of the South Wales Region (Region B, Sub-Region B1), and it is positioned encircled by minor roads, with the A483 road farther to its south-east, and has the town of Llanymddyfri (Llandovery) towards the south south-west. 

When the original 200m height band of Welsh P30 hills were published on Geoff Crowder’s v-g.me website, this hill was included in the Hills to be surveyed sub list that accompanied the main P30 list, as it was considered not to meet the criteria then used for the main P30 category. 

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 29m of drop, based on an estimated c 283m summit height and an estimated c 254m bwlch height, with both heights based on interpolation of 10m contouring that appear on the Ordnance Survey 1:25,000 Explorer map. 

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

The details for this hill were re-assessed when the Ordnance Survey Vector Map Local hosted on the Geograph website and which was entitled the Interactive Coverage Map became available online.  This mapping had many spot heights not on other publicly available Ordnance Survey maps and for this hill it had a 282m summit spot height and a 251m bwlch spot height, with these values giving this hill 31m of drop. 

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 summit image of Cefn Bwlch Cennant (SN 802 424)

The height produced by LIDAR analysis for the remaining natural summit is 281.168m and is positioned at SN 80249 42439, with LIDAR analysis also giving a raised field boundary positioned at SN 80245 42451 a height of 281.603m, and this comes within the parameters of the Summit Relocations used within this page heading, these parameters are: 

The term Summit Relocations applies to when the high point is positioned in a different field, to a different feature such as a conifer plantation, within a different map contour, a different point where a number of potential summit positions are within close proximity, when natural ground or the natural and intact summit is confirmed compared to a higher point such as a raised field boundary or covered reservoir that is considered 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 summit height produced by LIDAR analysis is 281.2m and this is positioned at SN 80249 42439, this position is relatively close to where the 282m spot height appeared on the Ordnance Survey Vector Map Local hosted on the Geograph website and which was entitled the Interactive Coverage Map and importantly to the remaining natural summit of this hill as opposed to the slightly higher raised field boundary.

 

ills of Wales, and are reproduced below@

The full details for the hill are: 

Group:  Drygarn Fawr 

Name:  Cefn Bwlch Cennant 

OS 1:50,000 map:  147, 160

Summit Height:  281.2m (LIDAR) 

Summit Grid Reference (New Position):  SN 80249 42439 (LIDAR) 

Bwlch Height:  250.55m (LIDAR) 

Bwlch Grid Reference:  SN 80310 42683 (LIDAR) 

Drop:  30.6m (LIDAR) 

 

Myrddyn Phillips (January 2022)

 

 

 

 

 

Mapping Mountains – Hill Reclassifications – 200m Twmpau

Cefn Bwlch Cennant (SN 802 424) – 200m Sub-Twmpau reclassified to 200m Twmpau

There has been confirmation of a reclassification to the list of 200m Twmpau, 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 Cefn Bwlch Cennant (SN 802 424)

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

200m Twmpau – Welsh hills at or above 200m and below 300m in height that have 30m minimum drop, with an accompanying sub list entitled the 200m Sub-Twmpau with the criteria for this sub category being all Welsh hills at or above 200m and below 300m 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 200m Twmpau by Myrddyn Phillips

The name the hill is listed by is Cefn Bwlch Cennant and this was derived from the Tithe map, and it is adjoined to the Drygarn Fawr group of hills, which are situated in the central part of the South Wales Region (Region B, Sub-Region B1), and it is positioned encircled by minor roads, with the A483 road farther to its south-east, and has the town of Llanymddyfri (Llandovery) towards the south south-west. 

When the original 200m height band of Welsh P30 hills were published on Geoff Crowder’s v-g.me website, this hill was included in the Hills to be surveyed sub list that accompanied the main P30 list, as it was considered not to meet the criteria then used for the main P30 category. 

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 29m of drop, based on an estimated c 283m summit height and an estimated c 254m bwlch height, with both heights based on interpolation of 10m contouring that appear on the Ordnance Survey 1:25,000 Explorer map. 

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

The details for this hill were re-assessed when the Ordnance Survey Vector Map Local hosted on the Geograph website and which was entitled the Interactive Coverage Map became available online.  This mapping had many spot heights not on other publicly available Ordnance Survey maps and for this hill it had a 282m summit spot height and a 251m bwlch spot height, with these values giving this hill 31m of drop. 

Another of the mapping resources now available online is the Magic Maps website which hosts an interactive map originated from Ordnance Survey data.  This mapping also shows a 282m spot height on the summit area of this hill. 

Extract from the Magic Maps website

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 confirmation of the reclassification of this hill from 200m Sub-Twmpau status is due to LIDAR analysis, resulting in a 281.2m summit height and a 250.55m bwlch height, with these values giving this hill 30.6m of drop, which is sufficient for it to be classified as a 200m Twmpau.  With the caveat that LIDAR gives a 281.6m height to a raised boundary bank that is considered a relatively recent man-made construct and therefore is not taken as a part of the height of this hill. 

 

The full details for the hill are: 

Group:  Drygarn Fawr 

Name:  Cefn Bwlch Cennant 

OS 1:50,000 map:  147, 160

Summit Height:  281.2m (LIDAR) 

Summit Grid Reference:  SN 80249 42439 (LIDAR) 

Bwlch Height:  250.55m (LIDAR) 

Bwlch Grid Reference:  SN 80310 42683 (LIDAR) 

Drop:  30.6m (LIDAR) 

 

Myrddyn Phillips (January 2022)