Mapping Mountains – Significant Name Changes – The Welsh P15s

 

Ysgellog & Minffordd (SH 409 912) 

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 Ysgellog & Minffordd (SH 409 912)

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 encircled by minor roads with the A5025 road farther to the north and the B5111 road farther to the south-east, and has the town of Amlwch towards the east north-east. 

When the listing that became known as The Welsh P15s was being compiled, this hill was listed under the point (Pt. c 65m) notation with an estimated c 23m of drop based on an estimated c 65m summit height and the 42m 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 143 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 Ysgellog & Minffordd in the apportionments, with the details on the Tithe map appearing in the parish of Amlwch 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 Ysgellog & Minffordd and this was derived from the Tithe map. 

 

The full details for the hill are: 

Group:  Ynys Môn 

Name:  Ysgellog & Minffordd

Previously Listed Name:  Pt. c 65m 

OS 1:50,000 map:  114

Summit Height:  60.2m (LIDAR) 

Summit Grid Reference:  SH 40921 91218 & SH 40923 91218 & SH 40925 91220 (LIDAR) 

Bwlch Height:  41.7m (LIDAR) 

Bwlch Grid Reference:  SH 40915 91509 (LIDAR) 

Drop:  18.5m (LIDAR) 

 

Myrddyn Phillips (July 2021)

 

 

 

 

 

Mapping Mountains – Significant Height Revisions – The Welsh P15s

Ysgellog & Minffordd (SH 409 912) 

There has been a Significant Height Revision 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 Ysgellog & Minffordd (SH 409 912)

The criteria for the list that this height revision 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 name the hill is listed by is Ysgellog & Minffordd 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 encircled by minor roads with the A5025 road farther to the north and the B5111 road farther to the south-east, and has the town of Amlwch towards the east north-east. 

When the listing that became known as The Welsh P15s was being compiled, this hill was listed with an estimated c 23m of drop based on an estimated c 65m summit height and the 42m 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. 

The summit height produced by LIDAR analysis is 60.2m 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, this hill’s new listed summit height is 60.2m and this was derived from LIDAR analysis, this is 4.8m lower than the previous listed summit height of c 65m which was based on interpolation of what was thought to be an uppermost 65m ring contour that appears on the Ordnance Survey 1:25,000 Explorer map. 

 

ills of Wales, and are reproduced below@

The full details for the hill are: 

Group:  Ynys Môn 

Name:  Ysgellog & Minffordd 

OS 1:50,000 map:  114

Summit Height (New Height):  60.2m (LIDAR) 

Summit Grid Reference:  SH 40921 91218 & SH 40923 91218 & SH 40925 91220 (LIDAR) 

Bwlch Height:  41.7m (LIDAR) 

Bwlch Grid Reference:  SH 40915 91509 (LIDAR) 

Drop:  18.5m (LIDAR) 

 

Myrddyn Phillips (July 2021)

 

 

 

 

 

 

 

  

Mapping Mountains – Hill Reclassifications – 30-99m Twmpau

Ysgellog & Minffordd (SH 409 912) – 30-99m Sub-Twmpau deletion

There has been a deletion 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 Ysgellog & Minffordd (SH 409 912)

The criteria for the list that this deletion 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 Ysgellog & Minffordd 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 encircled by minor roads with the A5025 road farther to the north and the B5111 road farther to the south-east, and has the town of Amlwch towards the east north-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 an estimated c 23m of drop based on an estimated c 65m summit height and the 42m 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 deletion of this hill from 30-99m Sub-Twmpau status is due to LIDAR analysis, resulting in a 60.2m summit height and a 41.7m bwlch height, with these values giving this hill 18.5m of drop, which is insufficient for it to be classified as a 30-99m Sub-Twmpau. 

 

The full details for the hill are: 

Group:  Ynys Môn 

Name:  Ysgellog & Minffordd 

OS 1:50,000 map:  114

Summit Height:  60.2m (LIDAR) 

Summit Grid Reference:  SH 40921 91218 & SH 40923 91218 & SH 40925 91220 (LIDAR) 

Bwlch Height:  41.7m (LIDAR) 

Bwlch Grid Reference:  SH 40915 91509 (LIDAR) 

Drop:  18.5m (LIDAR) 

 

Myrddyn Phillips (June 2021)