Mapping Mountains – Hill Reclassifications – Welsh Highlands – Uchafion Cymru

 

Elidir Fach (SH 603 613) – Welsh Highland Sub reinstatement 

There has been a reinstatement to the listing of the Welsh Highlands – Uchafion Cymru, with the summit height, bwlch height and their locations, the drop and status of the hill derived from a Trimble GeoXH 6000 survey conducted by Aled Williams. 

The summit area of Elidir Fach (SH 603 613).  Photo: Aled Williams

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

Welsh Highlands – Uchafion Cymru – Welsh hills at or above 500m in height with 15m minimum drop, with an accompanying sub list entitled the Welsh Highland Subs, the criteria for which is all Welsh hills at or above 500m in height with 10m or more and below 15m of drop.  This list is authored by Myrddyn Phillips and Aled Williams with the Introduction to the list published on Mapping Mountains in November 2015 and the latest update relating to the list published on Mapping Mountains in January 2023.

Welsh Highlands - Uchafion Cymru by Aled Williams and Myrddyn Phillips

The name the hill is listed by is Elidir Fach and it is adjoined to the Glyder Fawr group of hills, which are situated in the north-western part of North Wales (Region A, Sub-Region A1), and it is positioned with minor roads to its north and west, the A5 road to its north-east and the A4086 road to its south-west, and has the village of Llanberis towards the south-west. 

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

When the initial P10 sub list was completed in June 2020 this hill was listed as a Welsh Highland Sub with 13.5m of drop, based on a basic levelling survey conducted by Myrddyn Phillips on the 22.05.98, and listed with an estimated c 800m summit height relative to its bwlch height, and a 786m bwlch height, with the latter based on detail on the enlarged-scale Ordnance Survey map hosted on the coflein.gov.uk website. 

LIDAR image of Elidir Fach (SH 603 613)

The hill was subsequently analysed via LIDAR by Aled Williams, resulting in a 794.5m summit height and a 784.7.1m bwlch height, with these values giving this hill 9.8m of drop, which was insufficient for it to be classified as a Welsh Highland Sub.  However, with the drop value relatively close to the qualifying criterion of 10m this hill was prioritised for a survey with the Trimble GeoXH 6000. 

The bwlch area of Elidir Fach (summit at SH 603 613).  Photo: Aled Williams

Therefore, the reinstatement of this hill to Welsh Highland Sub status is due to a Trimble GeoXH 6000 survey, resulting in a 794.2m summit height and a 784.2m bwlch height, with these values giving this hill 10.0m of drop, which is sufficient for it to be classified as a Welsh Highland Sub. 

 

The full details for the hill are: 

Group:  Glyder Fawr

Name:  Elidir Fach           

OS 1:50,000 map:  115

Summit Height:  794.2m (converted to OSGM15, Trimble GeoXH 6000)

Summit Grid Reference:  SH 60377 61341 (Trimble GeoXH 6000)

Bwlch Height:  784.2m (converted to OSGM15, Trimble GeoXH 6000)

Bwlch Grid Reference:  SH 60556 61279 (Trimble GeoXH 6000)   

Drop:  10.0m (Trimble GeoXH 6000) 

 

For the additions, deletions and reclassifications to the Welsh Highlands – Uchafion Cymru reported on Mapping Mountains please consult the following Change Registers:

 

Welsh Highland P15s

 

Welsh Highland Subs

 

Aled Williams and Myrddyn Phillips (November 2024)

 

 

 

Mapping Mountains – Trimble Surveys – Glyder Fawr

17.08.24  Elidir Fach (SH 603 613) 

A chilly early morning walk through the upper portion of Chwarel Dinorwig brought me onto the open hillside beneath the summit of Elidir Fach.  Shortly after the release of new Welsh LIDAR data in early 2023, this hill was deleted from the Subs of The Welsh Highlands list due to the resultant 9.8m drop failing the 10.0m qualification threshold.  Ever since, this hill has been high on the priority list for an accurate Trimble GeoXH 6000 survey.

The first survey for summit position and height.  Photo: Aled Williams.

The summit of Elidir Fach consists of a shelter-cairn built around small outcrops of rock, one of which being a contender for the high point of the hill.  Beside the cairn on the north side is another contender, a small outcropping rock, seemingly at the central point of the summit dome.  A third contender is a larger boulder found to the south of the cairn among a collection of weathered outcrops.  I checked each out from various angles with an Abney level, but struggled to definitively rule out one of the others.  There was only one thing for it – three summit surveys were necessary!

The second survey for summit position and height.  Photo: Aled Williams.

I thankfully had the summit all to myself for the duration of the surveying, free of distraction and interruption.  This proved unusual as over the next hour no fewer than eight people would come and go from this minor top.

The summit area with the Trimble at the third summit contender.  Photo: Aled Williams.

The next phase was to survey the bwlch, which I knew in advance would entail two sets of measurements given that LIDAR data gave two positions of equal height.  I was however glad of LIDAR positioning, as the flat expanse of the bwlch made judging the low point by eye extremely difficult.

The bwlch backed by the upper slope of Elidir Fawr.  Photo: Aled Williams.

As data collected on the bwlch, I looked upon the continuation of the Eryri peaks either side of it with the pastoral lands of Môn stretching on beyond the Menai.  I felt glad to be born a Welshman!  I packed up the equipment and headed back down to the car.  It had been an enjoyable morning on the hill and I was looking forward to know the outcome of the surveying work.

Surveying one of the two options for the critical bwlch.  Photo: Aled Williams.

Surveying one of the two options for the critical bwlch.  Photo: Aled Williams.

 

Aled Williams (August 2024)

 

Survey Result: 

 

Elidir Fach

Summit Height:  794.2m (converted to OSGM15)

Summit Grid Reference:  SH 60377 61341

Bwlch Height:  784.2m (converted to OSGM15)

Bwlch Grid Reference:  SH 60556 61279

Drop:  10.0m (Welsh Highland Sub reinstatement)

Dominance:  1.26%

 

 

For further details please consult the Trimble Survey Spreadsheet

 

 

 

  

Mapping Mountains – Hill Reclassifications – Welsh Highlands – Uchafion Cymru

DUE TO A TRIMBLE GEOXH 6000 SURVEY THIS HILL HAS SUBSEQUENTLY BEEN REINSTATED TO WELSH HIGHLAND SUB STATUS

Elidir Fach (SH 603 613) – Welsh Highland Sub deletion 

There has been a deletion to the listing of the Welsh Highlands – Uchafion Cymru, with the summit height, bwlch height and their locations, the drop and status of the hill derived from LIDAR analysis conducted by Aled Williams. 

LIDAR image of Elidir Fach (SH 603 613)

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

Welsh Highlands – Uchafion Cymru – Welsh hills at or above 500m in height with 15m minimum drop, with an accompanying sub list entitled the Welsh Highland Subs, the criteria for which is all Welsh hills at or above 500m in height with 10m or more and below 15m of drop.  This list is authored by Myrddyn Phillips and Aled Williams with the Introduction to the list published on Mapping Mountains in November 2015 and the latest update relating to the list published on Mapping Mountains in January 2023.

Welsh Highlands - Uchafion Cymru by Myrddyn Phillips and Aled Williams

The name the hill is listed by is Elidir Fach and it is adjoined to the Glyder Fawr group of hills, which are situated in the north-western part of North Wales (Region A, Sub-Region A1), and it is positioned with minor roads to its north and west, the A5 road to its north-east and the A4086 road to its south-west, and has the village of Llanberis towards the south-west. 

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

When the initial P10 sub list was completed in June 2020 this hill was listed as a Welsh Highland Sub with 13.5m of drop, based on a basic levelling survey conducted by Myrddyn Phillips on the 22.05.98, and listed with an estimated c 800m summit height relative to its bwlch height, and a 786m bwlch height, with the latter based on detail on the enlarged-scale Ordnance Survey map hosted on the coflein.gov.uk 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 deletion of this hill from Welsh Highland Sub status is due to LIDAR analysis, resulting in a 794.5m summit height and a 784.7m bwlch height, with these values giving this hill 9.8m of drop, which is insufficient for it to be classified as a Welsh Highland Sub. 

 

The full details for the hill are: 

Group:  Glyder Fawr

Name:  Elidir Fach

OS 1:50,000 map:  115

Summit Height:  794.5m (LIDAR)

Summit Grid Reference:  SH 60378 61339 (LIDAR)

Bwlch Height:  784.7m (LIDAR)

Bwlch Grid Reference:  SH 60556 61279 (LIDAR)   

Drop:  9.8m (LIDAR) 

 

For the additions, deletions and reclassifications to the Welsh Highlands – Uchafion Cymru reported on Mapping Mountains please consult the following Change Registers:

 

Welsh Highland P15s

 

Welsh Highland Subs

 

Aled Williams and Myrddyn Phillips (June 2023)