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

Cae Penorsedd (SH 305 834) 

There has been a Significant Name Change to a hill that is listed in the 30-99m 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 Cae Penorsedd (SH 305 834)

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

The 30-99m Twmpau by Myrddyn Phillips

The hill is adjoined to the Ynys Môn group of hills, which are situated in the north-western part of North Wales (Region A, Sub-Region A1), and it is positioned with the coast to its west, minor roads to its north and west and the A5025 road to its south-east, and has the village of Llanfachreth towards the south-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 not included in the Hills to be surveyed sub list, as it was considered not to meet the criteria then used for this sub category. 

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 under the point (Pt. 33m) notation with 24m of drop based on the 33m summit spot height that appears on the Ordnance Survey 1:25,000 Explorer map and the 9m bwlch spot height that appeared on the Ordnance Survey Vector Map Local hosted on the Geograph website and which was entitled the Interactive Coverage Map. 

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 77 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 Cae Penorsedd in the apportionments, with the details on the Tithe map appearing in the parish of Llanfwrog and in the county named as Anglesey. 

Extract from the apportionments

Therefore, the name this hill is now listed by in the 30-99m Twmpau is Cae Penorsedd, and this was derived from the Tithe map. 

 

The full details for the hill are: 

Group:  Ynys Môn 

Name:  Cae Penorsedd

Previously Listed Name:  Pt. 33m 

OS 1:50,000 map:  114

Summit Height:  33.5m (LIDAR) 

Summit Grid Reference:  SH 30528 83481 (LIDAR) 

Bwlch Height:  9.9m (LIDAR) 

Bwlch Grid Reference:  SH 30834 83544 (LIDAR) 

Drop:  23.65m (LIDAR) 

 

Myrddyn Phillips (June 2021)

 

 

  

Mapping Mountains – Hill Reclassifications – 30-99m Twmpau

 

Cae Penorsedd (SH 305 834) – 30-99m Sub-Twmpau addition

There has been confirmation of an addition to the list of 30-99m 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 Cae Penorsedd (SH 305 834) 

The criteria for the list that this addition 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. 

The 30-99m Twmpau by Myrddyn Phillips

The name the hill is listed by is Cae Penorsedd and this was derived from the Tithe map and it is adjoined to the Ynys Môn group of hills, which are situated in the north-western part of North Wales (Region A, Sub-Region A1), and it is positioned with the coast to its west, minor roads to its north and west and the A5025 road to its south-east, and has the village of Llanfachreth towards the south-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 not included in the Hills to be surveyed sub list, as it was considered not to meet the criteria then used for this sub category. 

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 24m of drop based on the 33m summit spot height that appears on the Ordnance Survey 1:25,000 Explorer map and the 9m bwlch spot height that appeared on the Ordnance Survey Vector Map Local hosted on the Geograph website and which was entitled the Interactive Coverage Map. 

Extract from the Ordnance Survey 1:25,000 Explorer 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 confirmation of the addition of this hill to 30-99m Sub-Twmpau status is due to LIDAR analysis, resulting in a 33.5m summit height and a 9.9m bwlch height, with these values giving this hill 23.65m of drop, which is sufficient for it to be classified as a 30-99m Sub-Twmpau. 

 

The full details for the hill are: 

Group:  Ynys Môn 

Name:  Cae Penorsedd 

OS 1:50,000 map:  114

Summit Height:  33.5m (LIDAR) 

Summit Grid Reference:  SH 30528 83481 (LIDAR) 

Bwlch Height:  9.9m (LIDAR) 

Bwlch Grid Reference:  SH 30834 83544 (LIDAR) 

Drop:  23.65m (LIDAR) 

 

Myrddyn Phillips (June 2021)