Mapping Mountains – Significant Height Revisions – Y Trichant – The 300m Hills of Wales and Y Trechol – The Dominant Hills of Wales

 

Cefn y Coed (SO 211 934) 

There has been a Significant Height Revision to a hill that is listed in the Y Trichant – The 300m Hills of Wales and the Y Trechol – The Dominant Hills of Wales, with the summit height, bwlch height and their locations, the drop, the dominance and status of the hill derived from a Leica RX1250 survey conducted by Alan Dawson and a subsequent Trimble GeoXH 6000 summit survey and LIDAR bwlch analysis conducted by Myrddyn Phillips. 

Cefn y Coed (SO 211 934)

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

Y Trichant – The 300m Hills of Wales – Welsh hills at or above 300m and below 400m in height that have 30m minimum drop, with an accompanying sub list entitled the Sub-Trichant, with the criteria for this sub category being all Welsh hills at or above 300m and below 400m in height with 20m or more and below 30m of drop.  The list is authored by Myrddyn Phillips with the Introduction to the list and the renaming of it appearing on Mapping Mountains on the 13^th May 2017, and the Introduction to the Mapping Mountains publication of the list appearing on the 1^st January 2022. 

Y Trichant - The 300m Hills of Wales 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 Cefn y Coed and this was derived from the Tithe map, the Ordnance Survey One-Inch ‘Old Series’ map and local enquiry, and it is adjoined to the Cilfaesty group of hills, which are situated in the north-eastern part of South Wales (Region B, Sub-Region B2), and it is positioned with a minor road to its north and the A489 road to its south, and has the town of Trefaldwyn (Montgomery) to its north north-east.

When the original 300m height band of Welsh P30 hills were published on Geoff Crowder’s v-g.me website, this hill was listed with a non interpolated summit height of c 355m, based on the uppermost ring contour that appears on the Ordnance Survey 1:25,000 Explorer map. 

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

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 173m drop, based on an estimated c 356m summit height and an estimated c 183m bwlch height, with both heights based on interpolation of 5m contouring that appears on the Ordnance Survey 1:25,000 Explorer map. 

The Leica RX1250 set-up position at the summit of Cefn y Coed

However, it was not until the survey with the Leica RX1250 and subsequent LIDAR analysis and the survey with the Trimble GeoXH 6000 that the details for this hill could be accurately re-assessed. 

The Trimble GeoXH 6000 gathering data at the summit of Cefn y Coed

The summit height produced by the Leica RX1250 survey is 353.5m positioned at SO 21163 93413 and the summit height produced by the Trimble GeoXH 6000 survey is 353.6m positioned at SO 21164 93411, 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, Harvey or other interactive 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 with the data produced by the Trimble or by LIDAR analysis.

Therefore, the new listed summit height of this hill is 353.6m and this was derived from a Trimble GeoXH 6000 survey, this is 2.4m lower than the previously listed summit height of c 356m, which was based on interpolation of the uppermost ring contour that appears on the contemporary Ordnance Survey 1:25,000 Explorer map.

 

ills of Wales, and are reproduced below@

The full details for the hill are:

Group:  Cilfaesty

Name:  Cefn y Coed

OS 1:50,000 map:  137

Summit Height (New Height):  353.6m (converted to OSGM15, Trimble GeoXH 6000)

Summit Grid Reference:  SO 21164 93411 (Trimble GeoXH 6000)  

Bwlch Height:  184.2m (LIDAR)

Bwlch Grid Reference:  SO 20667 90868 (LIDAR)

Drop:  169.3m (Trimble GeoXH 6000 summit and LIDAR bwlch)

Dominance:  47.89% (Trimble GeoXH 6000 summit and LIDAR bwlch)

 

Myrddyn Phillips (May 2026)

Mapping Mountains – Hill Reclassifications – The Fours – The 400m Hills of England

 

Rhos Ffidl (SO 206 854) – Sub-Four addition

There has been an addition to the listing of the The Fours – The 400m Hills of England, with the summit height, col height and their locations, the drop and status of the hill derived from LIDAR analysis conducted by Myrddyn Phillips. 

LIDAR image of Rhos Ffidl (SO 206 854)

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

The Fours – The 400m Hills of England - English hills at or above 400m and below 500m in height that have 30m minimum drop, accompanying the main list is a sub list entitled the Sub-Fours, the criteria for which are all English hills at or above 400m and below 500m in height that have 15m or more and below 30m of drop.  The list is co-authored by Myrddyn Phillips and Aled Williams and is available to download in Google Doc format from the Mapping Mountains site.

The Fours - The 400m Hills of England by Myrddyn Phillips and Aled Williams

The name the hill is listed by is Rhos Ffidl, and it is adjoined to the Cilfaesty group of hills, which are situated adjoined to the Welsh border, and it is positioned with minor roads to its north-east and north-west, and the B4368 road towards the south, and has the village of Ceri (Kerry) towards the north-west.

When the Introduction to the first group of hills for the updated and revised listing of the The Fours – The 400m Hills of England was published by Mapping Mountains on the 10^th September 2022, it was announced that the accompanying sub lists were being revised with the two 390m categories dispensed with and the criteria and name of the 400m Sub-Fours revised.  The one accompanying sub list is now named the Sub-Fours with its criteria being all English hills 400m and above and below 500m in height that have 15m and more and below 30m of drop. 

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

Prior to this revision this hill was listed with an estimated c 14m of drop, based on the 422m summit spot height that appears on the Ordnance Survey 1:50,000 Landranger map and an estimated c 408m col height, based on interpolation of 5m contouring between 405m – 410m. 

Extract from the Ordnance Survey 1:50,000 Landranger 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 Sub-Four status is due to LIDAR analysis, resulting in a 422.7m summit height and a 407.1m col height, with these values giving this hill 15.7m of drop, which is sufficient for it to be classified as a Sub-Four. 

 

The full details for the hill are:

Group:  Cilfaesty

Name:  Rhos Ffidl

OS 1:50,000 map:  137

Summit Height:  422.7m (LIDAR)

Summit Grid Reference:  SO 20652 85426 (LIDAR)

Col Height:  407.1m (LIDAR)

Col Grid Reference:  SO 20510 85766 (LIDAR)

Drop:  15.7m (LIDAR)

 

For the additions, deletions and reclassifications to The Fours – The 400m Hills of England reported on Mapping Mountains since the December 2013 publication of the 1^st edition of this list by Europeaklist please consult the following Change Registers:

 

The Fours

 

Sub-Fours

 

Myrddyn Phillips and Aled Williams (May 2026)              

Mapping Mountains – Trimble Surveys – Hirddywel

 

08.05.26  Wenallt (SO 036 712)

The summit of Wenallt (SO 036 712)

Forested summits are not my favourites.  This isn’t surprising as many prove formidable to reach their highest point, entailing pathless slogs through enclosed conifers with skin ripping brambles and other unsavoury undergrowth encountered.  There are also some summits that resemble an assault course due to felled wind blown trees when upward progress seems impossible.  However, on occasion even these can give an unusual feeling of fulfillment if the summit is eventually reached.

Therefore, it wasn’t surprising that I had left Wenallt as my last Pedwar in this area of Wales, as although inviting tracks are shown on the Ordnance Survey 1:25,000 Explorer map, the hill looked a mass of uninviting conifer trees.

With a planned morning visit to the Powys archive at Llandod and knowing that this was my last Pedwar in the Hirddywel group of hills, Aled was enthusiastic for us to visit the hill in the afternoon.  The forecast wasn’t promising with heavy localised showers breaking out after midday, and as we left the archive at its 12.30pm closing time the clouds were massing with the prospect of those showers soon materialising.

It’s only a short drive from Llandod to Abaty Cwm-hir and we were soon parked just off the narrow road at the start of a forest rack.  A metal gate barred further vehicle access, and upon inspection we found this locked, so driving on the forest track to gain height was now out of the question.  Therefore, once walking boots were donned we set off up the wide expanse of gravelled track that led first northward away from the summit before swinging westward back toward it. 

A convenient parking place for the ascent of Wenallt

The early afternoon was slightly muggy and as my younger companion seemed to manage the uphill with hardly a breath out of place, I started to sweat and needed a few rests to try and compose my heartbeat and steady its increased thudding. 

The narrower track leading to the turning place

It was a tranquil scene in the forest, with rising mature conifers spreading toward the sky and occasional birdsong wafting from their heights.  The main forest track soon bisected with the branch we wanted now narrowing and heading south.  This culminated in a grassed area where forestry vehicles could turn.  We now had two options for further progress; one grassed track leading up to two felled trees and a slightly lower path that was narrower and lost a little height.  We opted for the higher one and soon clambered over the trees.  On our descent we headed through the mature forest to join the lower narrower path, and therefore bi-passing the two obstacles. 

The greens and blues of summer

Approaching the grassed turning circle

Having clambered over the two trees we were soon on a delightful path that meandered through the wood, always claiming height on a thankfully steady gradient.  Such paths are seldom found in conifer forests.  The path forever weaved its way up through the wood, with dappled sunlight occasionally casting through the trees, adding a welcome highlight of colour to the scene. 

A direct approach toward the summit looked horrendous

The green track beyond the turning circle with the two fallen trees ahead

Thankfully the forecast showers never materialised in this part of the country, with only a few spots of rain appearing as our route through the trees reached the upper broad easterly ridge of the hill.  Here we swung rightward with the path continuing its delightful meander through the trees. 

On the path that meandered through the wood

Close to the summit another large fallen tree meant a slight diversion was needed, but such occurrences were rare and the ones encountered never difficult to overcome.  Aled reached the summit before me; this comprises a small outcrop with vegetation overflowing from its upper reaches.  The outcrop is easy to get up with only thin branches from enclosing trees as hindrance. 

On the broad easterly ridge leading toward the summit

I followed and with Aled vacating the small area of the high point I soon stood on the summit.  Making our way back down we examined the outcrop and pondered what a lovely ridge walk this would have been prior to the influx of conifers, and what a shame it was that those planting the forestry had no foresight to leave the summit area free of trees. 

Aled on the summit of Wenallt

The outcrop that constitutes the summit of Wenallt

Our route proved ideal, with the upper part of an approach from the west looking horrendous as a jumble of trees barred any passage through.  All that remained was to retrace our steps down the broad easterly ridge before swinging north on our delightful inward path, with Aled leading the way through the mature trees to gain the lower path close to the turning place so we could avoid the two fallen trees clambered over on our ascent.  We were back at the car by 3.15pm, with the walk having taken 1hr 50min.

Another Pedwar visited taking my total to 364 hills, with 448 hills in all it would be tempting to concentrate on the remainder, but my baggng mentality has changed over recent years and I gain almost as much pleasure from repeat ascents as I do from visiting new hills, so for me I doubt I’ll finish this list. 

   

Survey Result:

 

Wenallt

Summit Height:  471.9m (LIDAR) 

Summit Grid Reference:  SO 03697 71231 (LIDAR) 

Bwlch Height:  372.7m (LIDAR)

Bwlch Grid Reference:  SO 03481 72058 (LIDAR)

Drop:  99.2m (LIDAR)

Dominance:  21.01% (LIDAR)

 

 

For further details please consult the Trimble Survey Spreadsheet

Mapping Mountains - Summit Relocations – The 500-Metre Tops of England and Wales – Deweys

 

Foel Fawr (SH 728 392) 

There has been a Summit Relocation that is retrospective to a hill that is listed in the The 500-Metre Tops of England and Wales, with the summit height, bwlch height and their locations, the drop and status of the hill confirmed by a Trimble GeoXH 6000 survey conducted by Myrddyn Phillips and Aled Williams on the 19^th July 2020.

Foel Fawr (SH 728 392)

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

The 500-Metre Tops of England and Wales are affectionately known after their hill list compiler; Michael Dewey.  This list mixes metric and imperial height in its criteria to bookend up to the 2000ft height band and takes in all hills in England, Isle of Man and Wales that are 500m and above and below 2000ft (609.6m) in height that have 30m minimum drop. 

Mountain tables by Michael Dewey

Michael Dewey died on the 5^th November 2022.  His wife; Gillian wished for this list to be carried on and made provision for it to be co-authored by Myrddyn Phillips.  Michael will always be the compiler and originator, it’s just that he’s now got a co-author to safeguard this list and carry this list on.

The name the hill is listed by is Foel Fawr and it is adjoined to the Arenig Fach group of hills, which are situated in the central part of North Wales, and it is positioned with the B4391 road to its north, the A470 road to its west and the A4212 road to its south, and has the village of Trawsfynydd towards the south-west.

When the original list of Deweys appeared in the Mountain tables book published by Constable in 1995, this hill was listed with a 528m summit height positioned at SH 726 395, based on the spot height that appears on the Ordnance Survey 1:25,000 Explorer map.

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

Since the original compilation of this list there have been a number of Ordnance Survey maps made available online, some of these are historic such as the series of Six-Inch maps on the National Library of Scotland website, whilst others are current and digitally updated such as the Ordnance Survey Vector Map Local that was hosted on the Geograph website and which was entitled the Interactive Coverage Map, and it was this map that showed a 528m map heighted twin summit positioned at SH 728 392.  The two 528m spot heights are also shown on the mapping hosted on the Magic Maps website. 

Extract from the Magic Maps website

However, it was not until the survey with the Trimble GeoXH 6000 that the details for this hill could be accurately re-assessed.  The height and position for each summit is given below: 

 

South-easterly summit:  528.611m at SH 72872 39284 

North-westerly summit:  527.542m at SH 72621 39476 

 

The above detail compared to the original summit position comes within the parameters of the Summit Relocations used within this page heading, these parameters are: 

The term Summit Relocations applies when the high point of the hill is found to be positioned; in a different field, to a different feature such as in a conifer plantation,  within a different map contour either on Ordnance Survey maps or interactive mapping, to a different point where a number of potential summit positions are within close proximity, 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 or covered reservoir that is considered a relatively recent man-made construct, or the listing of a new twin summit or de-twinning of a summit, 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. 

The Trimble GeoXH 6000 gathering data at the higher of the Foel Fawr summits

The Trimble GeoXH 6000 gathering data at the lower of the Foel Fawr summits

Therefore, the summit height produced by the Trimble GeoXH 6000 survey is 528.6m and this is positioned at SH 72872 39284, this position is not given a spot height on contemporary Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer maps, but is given a 528m spot height on the mapping hosted on the Magic Maps website, and is approximately 260 metres south-eastward from where the original listed summit is positioned. 

 

The full details for the hill are:

Group:  Arenig Fach

Name:  Foel Fawr

OS 1:50,000 map:  124

Summit Height:  528.6m (converted to OSGM15, Trimble GeoXH 6000)

Summit Grid Reference (New Position):  SH 72872 39284 (Trimble GeoXH 6000)  

Bwlch Height:  485.5m (converted to OSGM15, Trimble GeoXH 6000)

Bwlch Grid Reference:  SH 73074 39525 (Trimble GeoXH 6000)

Drop:  43.1m (Trimble GeoXH 6000 summit and bwlch)

 

Myrddyn Phillips (May 2026)