Mapping Mountains – Significant Height Revisions – 30-99m Twmpau

Menai Rock (SH 555 716) 

There has been a Significant Height Revision 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 derived from LIDAR analysis conducted by Myrddyn Phillips. 

LIDAR image of Menai Rock (SH 555 716)

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

30-99m Twmpau - Welsh hills at or above 30m and below 100m in height with 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 Menai Rock 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 A545 road to its immediate north-west and the A5 road to its south, and has the town of Porthaethwy (Menai Bridge) surrounding it. 

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 an estimated c 19m of drop based on the 31m 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 12m bwlch height based on interpolation of 5m contouring between 10m – 15m that appear on the Ordnance Survey 1:25,000 Explorer 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. 

The summit height produced by LIDAR analysis is 33.1m, 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. 

LIDAR summit image of Menai Rock

Therefore, this hill’s new listed summit height is 33.1m and this was derived from LIDAR analysis, this is 2.1m higher than the previous listed summit height of 31m which was based on the spot height that appeared on the Ordnance Survey Vector Map Local hosted on the Geograph website and which was entitled the Interactive Coverage Map.

 

ills of Wales, and are reproduced below@

The full details for the hill are:

Group:  Ynys Môn 

Name:  Menai Rock 

OS 1:50,000 map:  114, 115

Summit Height (New Height):  33.1m (LIDAR) 

Summit Grid Reference:  SH 55569 71697 (LIDAR) 

Bwlch Height:  9.0m (LIDAR) 

Bwlch Grid Reference:  SH 55622 72078 (LIDAR) 

Drop:  24.1m (LIDAR) 

 

Myrddyn Phillips (April 2021)

 

  

Mapping Mountains – Significant Name Changes – 100m Twmpau

Bryn Bras (SN 573 772) 

There has been a Significant Name Change to a hill that is listed in the 100m Twmpau, with the summit height, bwlch height and their locations, the drop and status of the hill derived from LIDAR analysis and a subsequent Trimble GeoXH 6000 survey conducted by Myrddyn Phillips. 

Bryn Bras (SN 573 772)

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 100m Twmpau by Myrddyn Phillips

The hill is adjoined to the Elenydd group of hills, which are situated in the central part of the Mid and West Wales Region (Region B, Sub-Region B2), and it is positioned with the coast to its west and a minor road to its immediate east with the A487 road farther to its east, and has the town of Aberystwyth towards the north north-east. 

When the original 100m height band of Welsh P30 hills were published on Geoff Crowder’s v-g.me website this hill was listed under the invented and transposed name of Pen Morfa Bychan, with an accompanying note stating; Name from buildings to the West.

Pen Morfa Bychan

169m

SN573772

135

213

Name from buildings to the 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.  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 104 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 Bryn Bras in the apportionments, with the details on the Tithe map appearing in the parish of Llanychaearn and in the county named as Cardigan. 

Extract from the apportionments

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

 

The full details for the hill are: 

Group:  Elenydd 

Name:  Bryn Bras

Previously Listed Name:  Pen Morfa Bychan 

OS 1:50,000 map:  135

Summit Height:  169.8m (converted to OSGM15, Trimble GeoXH 6000) 

Summit Grid Reference:  SN 57323 77231 (Trimble GeoXH 6000) 

Bwlch Height:  127.7m (LIDAR) 

Bwlch Grid Reference:  SN 57194 76934 & SN 57199 76941 (LIDAR) 

Drop:  42.1m (Trimble GeoXH 6000 summit and LIDAR bwlch) 

 

Myrddyn Phillips (April 2021)

 

 

 

 

 

 

 

  

Mapping Mountains – Significant Name Changes – The Welsh P15s

Tŷ Dylifws (SH 501 833) 

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 and detail on contemporary maps produced from Ordnance Survey data. 

LIDAR image of Tŷ Dylifws (SH 501 833)

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 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 B5110 road to its west and minor roads to its north, south and east, and has the village of Brynteg towards the south-west. 

When the listing that became known as The Welsh P15s was being compiled, this hill was listed under the point (Pt. 110m) notation with an estimated c 16m of drop, based on the 110m 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 94m bwlch height based on interpolation of 5m contouring between 90m – 95m. 

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 127 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 Tŷ Dylifws in the apportionments, with the details on the Tithe map appearing in the parish of Llanfair Mathafarn Eithaf and in the county named as Anglesey. 

Extract from the apportionments

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

 

The full details for the hill are: 

Group:  Ynys Môn 

Name:  Tŷ Dylifws

Previously Listed Name:  Pt. 110m 

OS 1:50,000 map:  114, 115

Summit Height:  109.3m (LIDAR) 

Summit Grid Reference:  SH 50184 83304 (LIDAR) 

Bwlch Height:  c 94m (interpolation) 

Bwlch Grid Reference:  SH 50035 82841 (interpolation) 

Drop:  c 15m (LIDAR summit and interpolated bwlch) 

 

Myrddyn Phillips (April 2021)

 

 

 

 

 

 

 

  

Mapping Mountains – Summit Relocations – 100m Twmpau and Y Trechol – The Dominant Hills of Wales

 

Banc Tŷ Hen (SN 650 895) 

There has been a Summit Relocation to a hill that is listed in the 100m 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 Banc Tŷ Hen (SN 650 895)

The criteria for the two listings that this summit relocation 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 100m 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 listed by is Banc Tŷ Hen and it is adjoined to the Pumlumon group of hills, which are situated in the north-western part of Mid and West Wales (Region B, Sub-Region B2), and it is positioned with minor roads to its north and west and the A487 road and the Afon Leri to its south-east, and has the small community of Tal-y-bont towards the south-east. 

When the original Welsh 100m P30 list was published on Geoff Crowder’s v-g.me website this hill was listed with a 157m summit height based on the spot height that appears on the Ordnance Survey 1:25,000 Explorer map and which is positioned at SN 64770 89387. 

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 is entitled the Interactive Coverage Map became available online.  This mapping had many spot heights not on other publicly available Ordnance Survey maps and gives a second 157m spot height on the area of this hill’s summit positioned at SN 65036 89542. 

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 157.4m and is positioned at SN 65012 89554.  When compared to the original listed summit position the above detail comes within the parameters of the Summit Relocations used within this page heading, these parameters are: 

The term Summit Relocations applies when the hill’s high point is found to be positioned; in a different field, to a different feature such as in a conifer plantation, placed within a different map contour, to a different point where a number of potential summit positions are within close proximity, or 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 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 summit height produced by LIDAR analysis is 157.4m and this is positioned at SN 65012 89554, this is approximately 300 metres north-eastward from where the original listed summit was given which was to the position of the 157m spot height on the Ordnance Survey 1:25,000 Explorer map. 

 

The full details for the hill are:

Group:  Pumlumon

Name:  Banc Tŷ Hen

OS 1:50,000 map:  135

Summit Height:  157.4m (LIDAR)

Summit Grid Reference (New Position):  SN 65012 89554 (LIDAR)

Bwlch Height:  63.7m (LIDAR)

Bwlch Grid Reference:  SN 65510 89668 (LIDAR)

Drop:  93.6m (LIDAR)

Dominance:  59.49% (LIDAR)

 

Myrddyn Phillips (April 2021)

 

 

Mapping Mountains – Hill Reclassifications – 30-99m Twmpau

Menai Rock (SH 555 716) – 30-99m Sub-Twmpau addition

There has been 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 Menai Rock (SH 555 716)

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 Menai Rock 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 A545 road to its immediate north-west and the A5 road to its south, and has the town of Porthaethwy (Menai Bridge) surrounding it. 

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 an estimated c 19m of drop based on the 31m 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 12m bwlch height based on interpolation of 5m contouring between 10m – 15m that appear on the Ordnance Survey 1:25,000 Explorer 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 addition of this hill to 30-99m Sub-Twmpau status is due to LIDAR analysis, resulting in a 33.1m summit height and a 9.0m bwlch height, with these values giving this hill 24.1m 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:  Menai Rock 

OS 1:50,000 map:  114, 115

Summit Height:  33.1m (LIDAR) 

Summit Grid Reference:  SH 55569 71697 (LIDAR) 

Bwlch Height:  9.0m (LIDAR) 

Bwlch Grid Reference:  SH 55622 72078 (LIDAR) 

Drop:  24.1m (LIDAR) 

 

Myrddyn Phillips (April 2021)