Mapping Mountains – Significant Name Changes – Y Trichant – The 300m Hills of Wales

Cefn Penarth (SN 924 853)

There has been a Significant Name Change to a hill that is listed in the Y Trichant – The 300m Hills of Wales, with the summit height, bwlch height and their locations, the drop and status of the hill initially confirmed by Joe Nuttall who produced a summit analysis programme using LIDAR, and then by LIDAR analysis initially conducted by Jim Bloomer and subsequently by Myrddyn Phillips, with the hill previously surveyed with the Trimble GeoXH 6000.

LIDAR image of Cefn Penarth (SN 924 853)

The criteria for the list that this name change 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 13th May 2017.

Y Trichant - The 300m Hills of Wales by Myrddyn Phillips

The hill 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 between the river valleys of the Afon Clewedog to its north and the Afon Hafren (River Severn) to its south, and has a minor road running the length of its ridge and the B4518 road to its north-east, and has the town of Llanidloes towards the east south-east.

The hill appeared in the original Welsh 300m P30 list on Geoff Crowder’s v-g.me website under the partly invented and transposed name of Mynydd Cefn-penarth, with an accompanying note stating; Name from buildings to the North-East and North-West.

Mynydd Cefn-penarth

317m

SN925854

136

214

Name from buildings to the North-East and North-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 or as in this instance put the word Mynydd in front of that of a farm.  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

During the updating of this hill’s details I made local enquiries relating to its name and was told that the area of land taking in the ridge comprising this hill is known as Cefn Penarth.

Therefore, the name this hill is now listed by in the Y Trichant – The 300m Hills of Wales is Cefn Penarth, and this was derived from local enquiry.

The full details for the hill are:

Group:  Pumlumon

Name:  Cefn Penarth

Previously Listed Name:  Mynydd Cefn-penarth

OS 1:50,000 map:  136

Summit Height:  318.9m (LIDAR)

Summit Grid Reference:  SN 92419 85333 (LIDAR)

Bwlch Height:  288.9m (LIDAR)

Bwlch Grid Reference:  SN 92025 85612 (LIDAR)

Drop:  30.0m (LIDAR)

Myrddyn Phillips (October 2020)

Mapping Mountains – Hill Reclassifications – Y Trichant – The 300m Hills of Wales

Cefn Penarth (SN 924 853) – Sub-Trichant reclassified to Trichant

There has been a reclassification to the list of Y Trichant – The 300m Hills of Wales, with the summit height, bwlch height and their locations, the drop and status of the hill initially confirmed by Joe Nuttall who produced a summit analysis programme using LIDAR, and then by LIDAR analysis initially conducted by Jim Bloomer and subsequently by Myrddyn Phillips, with the hill previously surveyed with the Trimble GeoXH 6000.

Cefn Penarth (SN 924 853)

The criteria for the list that this reclassification 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 13th May 2017.

Y Trichant - The 300m Hills of Wales by Myrddyn Phillips

The name the hill is now listed by is Cefn Penarth and this was derived from local enquiry, 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 between the river valleys of the Afon Clewedog to its north and the Afon Hafren (River Severn) to its south, and has a minor road running the length of its ridge and the B4518 road to its north-east, and has the town of Llanidloes towards the east south-east.

When the original 300m height band of Welsh P30 hills was published on Geoff Crowder’s v-g.me website this hill was included in the Hills to be surveyed sub list, as it was considered not to meet the criteria then used for the accompanying main P30 list.

When 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 29m of drop based on the 317m summit spot height and the 288m bwlch spot height that appear on the Ordnance Survey 1:25,000 Explorer map.

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

As the listed drop was close to the 30m minimum drop required for Trichant status this hill was prioritised for a GNSS survey, and this took place on the 20^th April 2014, resulting in 29.8m of drop.  However, since this hill was Trimbled, LIDAR is now available and the summit analysis undertaken by Joe Nuttall and LIDAR analysis conducted by Jim Bloomer prompted me to compare the Trimble result against the LIDAR.  The Trimble result is 0.07m lower for the summit compared to LIDAR, but with an approximate 16 metre difference in summit position and a 7 metre difference in bwlch position, the LIDAR result is being prioritised.

LIDAR image of Cefn Penarth

The LIDAR (Light Detection & Ranging) technique produced highly accurate height data that is now freely available for much of England and Wales and is revolutionising hill classification.

Therefore, the reclassification of this hill from Sub-Trichant status is due to LIDAR analysis, resulting in a 318.9m summit height and a 288.9m bwlch height, with these values giving this hill 30.0m of drop, which is sufficient for it to be classified as a Trichant.

The full details for the hill are:

Group:  Pumlumon

Name:  Cefn Penarth

OS 1:50,000 map:  136

Summit Height:  318.9m (LIDAR)

Summit Grid Reference:  SN 92419 85333 (LIDAR)

Bwlch Height:  288.9m (LIDAR)

Bwlch Grid Reference:  SN 92025 85612 (LIDAR)

Drop:  30.0m (LIDAR)

For details on the Trimble GeoXH 6000 survey of this hill

Myrddyn Phillips (October 2020)

Mapping Mountains – Trimble Surveys – Pumlumon

20.04.14  Cefn Penarth (SN 924 853)

Cefn Penarth (SN 924 853), bwlch on right near to farm and the summit on the left

I’d spent some time the previous evening trying to find two or three hills of interest whose P30 status needed checking or whose Sub status stood a chance of being promoted to a P30.  One that met the latter description was a hill on a descending easterly ridge to the south of Llyn Clywedog.  To make things easier the ridge that the hill is situated on has a minor road following its crest.  However, there are farms either side of the bwlch and summit and it looked like prime sheep grazing land, and as it is now just past lambing time, these little beasts may be with their mothers on the fields I wanted to survey, so I had to show caution and respect toward the beasties.

The road from my last hill (Pt. 381.7m SN 926 875) heads south-eastward toward Llanidloes, after a mile I turned right and then a few minutes later I turned left on to a steep and seldom used road with unenclosed fields on my right, lambs scampering about and three gates to open.  I tried my utmost to encourage the lambs to stay in their given fields when opening these gates, but I’m afraid one escaped in to a neighbouring field, so no doubt she is now wandering around trying to discover a new mother.

I parked beside the track entrance that leads down to the Upper Cefn-penarth farm (SN 920 855).  I’d looked at this road on the digitised Google Map the previous evening and noted ground ground immediately to the north of the road where a 288m spot height appears on Ordnance Survey maps was higher.  I’d also zoomed up the lane toward the summit where a 317m spot height appears on the OS map.  The high point of the hill was above this road.  Could the height difference between the land at the bwlch and summit be sufficient for P30 status to be confirmed?

The 288m spot height appears on this lane, the critical bwlch is higher and in the field on the right

Once out of the car I walked westward up the road to acclimatise myself with the lay of the land at the bwlch, the ground immediately north of the lane proved higher, I looked around for any farm vehicles on adjacent fields and sneaked over the fence, saying good morning to two small lambs and their mother as I did so.  No sooner was I in the field and one of these lambs walked toward me and nuzzled my leg, I ignored its advances!

I needed to be quick as I was in full view of the lane and the Upper Cefn-penarth farm was only over the lip of the field, I spent a few minutes on my knees judging the lay of land, picked my spot and set the Trimble to gather data.  Once the Trimble had been activated I headed to the nearby hedge and sat in the field below it and next to a particularly dense covering of hedgey stuff.  Within a couple of minutes the rumbles of a vehicle from the farm came up the lane, oh gawd, imagine trying to explain what I was doing.  I waited for it to pass and then hoped it wouldn’t turn right, as if it did I would be in full view of the occupant as they passed the fence I had clambered over.  Thankfully they turned left and headed up the lane toward the summit of the hill.  Once five minutes of data were collected I quickly packed the equipment away and walked up the lane to a gate just over the crest of the hill, which gave access to the summit field.

The Trimble GeoXH 6000 set-up position at the bwlch of Cefn Penarth with the Llyn Clywedog dam in the background

Looking up the lane toward the summit

I gathered three data sets from the summit area of the hill, one from what I judged to be the high point, one from the high point near to the road and the third from the high point of an earthen embankment that ran parallel to the road.  In all fifteen minutes of data were collected from these points and the same amount of time was probably spent setting the equipment up, during which I wandered around in a field, next to a road, hoping that no farmer’s vehicle would pass me.  The only one I could see was a quad bike on a lower field; I tried to keep out of his line of sight.

The Trimble GeoXH 6000 gathering data at the second point on the summit area, the high point of the hill is to the left

By 10.55am I was back at the car and travelling toward Llanidloes and then Welshpool.  Soon after arriving home the predicted rain arrived.  A great morning, only done because I’d mistakenly visited the lower top of Dinas two days previously, so I had to re-visit to get another data set. 

LIDAR image of Cefn Penarth

POSTSCRIPT:

Since this hill was Trimbled, LIDAR has become available and summit analysis undertaken by Joe Nuttall and sent to DoBIH prompted me to compare the Trimble result to that ascertained from LIDAR.  The Trimble result is 0.07m lower for the summit compared to LIDAR, but with an approximate 16 metre difference in summit position and a 7 metre difference in bwlch position, the LIDAR result is being prioritised.  

Survey Result:

Cefn Penarth (significant name change)

Summit Height:  318.9m (LIDAR)

Summit Grid Reference:  SN 92415 85333 (LIDAR)

Bwlch Height:  288.9m (LIDAR)

Bwlch Grid Reference:  SN 92025 85612 (LIDAR)

Drop:  30.0m (LIDAR) (Sub-Trichant reclassified to Trichant)

Dominance:  9.41% (LIDAR)

For further details please consult the Trimble Survey Spreadsheet