Mapping Mountains – Trimble Surveys – Mynydd Sylen

01.08.18  Mynydd Sylen (SN 515 080)

Mynydd Sylen (SN 515 080)

Mynydd Sylen was the second of what was hoped to be six hills for the day, each using the most convenient access which for many proved no more than a few minutes stroll to their high point, and this hill did not prove otherwise.

My bagging accomplice for the day; Suzanne, navigated us from the high minor road that crosses Mynydd Penlle’rcastell (SN 664 094), down through the Rhydaman (Ammanford) road network toward the outskirts of Llan-non, and onward up a minor road to the small community of Sylen, where the northern branch at a cross roads led to the access gate to the large masts positioned near this hill’s summit.

The shower clouds from earlier in the morning had now been replaced with beautiful blue skies and summer warmth that followed us up the field adjacent to the access track leading toward the masts.

Although the weather was welcoming the hill felt neglected and despoiled, partly as fly tipping had taken place beside the access gate leading to the masts, but the presence of these large constructions had also taken a part of the hill’s atmospheric quality.  Added to this is the fact that the summit does not stand out even with a trig pillar positioned on it, as the ground surrounding it is relatively flat, therefore we took a number of minutes to decide where the highest natural ground was situated, once agreed the Trimble was positioned on it and I pressed ‘Log’ and we stood back waiting for the allotted data to be gathered and stored.

Gathering data at the summit of Mynydd Sylen (SN 515 080)

The Trimble set-up position at the summit of Mynydd Sylen

During this a small herd of inquisitive cows in an adjacent field all walked our way, standing back from the perimeter fence they looked on as we looked back at them.  They only headed off when we approached the fence, their browns and blacks adding colour contrast to the greened scene looking back toward the wind turbines near the summit of Mynydd Penlle’rcastell.

The small herd of inquisitive cows

Once the allotted data were gathered and stored I closed the Trimble down, packed it away and we headed the short distance back to my car.  Before continuing west toward our third hill of the day; Mynydd Llangyndeyrn (SN 482 132) I drove the short distance on the minor road to the top of another track which gave us extensive views east, and we sat chatting in the car and enjoying a picnic prepared by my bagging accomplice.

Survey Result:

Mynydd Sylen

Summit Height:  283.5m (converted to OSGM15, Trimble GeoXH 6000)

Summit Grid Reference:  SN 51528 08004 (Trimble GeoXH 6000)

Bwlch Height:  69.2m (LIDAR)

Bwlch Grid Reference:  SN 61836 18085 (LIDAR)

Drop:  214.3m (Trimble GeoXH 6000 summit and LIDAR bwlch)

Dominance:  75.60% (Trimble GeoXH 6000 summit and LIDAR bwlch)

For further details please consult the Trimble Survey Spreadsheet

Mapping Mountains – Significant Name Changes – 100m Twmpau

Caer Lleiniau Uchaf (SN 521 198)

There has been a Significant Name Change to a hill that is listed in the 100m Twmpau, with the summit height, drop and status of the hill being confirmed by LIDAR analysis conducted by Myrddyn Phillips.

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.

LIDAR image of Caer Lleiniau Uchaf

The hill is adjoined to the Mynydd Sylen group of hills, which are situated in the western part of South Wales (Region C, Sub-Region C1), and it is positioned with the B 4300 and A 40 roads, and the Afon Tywi (River Towy) to its north, and has the small community of Llanarthne towards the east north-east.

The hill appeared in the accompanying sub list to the 100m P30 list on Geoff Crowder’s v-g.me website under the name of Allt Cae-blawd, which is a name consistently given to a wooded area to the north-west of this hill’s summit on Ordnance Survey maps.  During my early hill listing I paid little regard to name placement on the map, or the meaning of names and to what feature the name was appropriately applied to.  Therefore I prioritised names for listing purposes that I now understand are either inappropriate or where another name is viewed as being more appropriate.

Allt Cae-blawd

110c

SN523195

159

186

Two points of same height - other at SN521198

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 1403 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 Caer Lleinau [sic] uchaf in the apportionments, with the details on the Tithe map appearing in the county named as Carmarthen and in the parish of Llanarthney [sic].

Extract from the apportionments

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

The full details for the hill are:

Group:  Mynydd Sylen

Name:  Caer Lleiniau Uchaf

Previously Listed Name:  Allt Cae-blawd 

Summit Height:  113.2m (LIDAR)

OS 1:50,000 map:  159

Summit Grid Reference:  SN 52155 19862 (LIDAR)

  

Drop:  31.2m (LIDAR)

Myrddyn Phillips (October 2018)

Mapping Mountains – Trimble Surveys – Mynydd Penlle’rcastell

01.08.18  Mynydd Penlle’rcastell (SN 664 095)

Mynydd Penlle'rcastell (SN 664 095)

The ruins of Penlle’rcastell stand atop a flattened mound of a hill overlooking the Afon Aman (River Amman) to its north; nowadays the whole hill is encircled by roads with the A474 following the course of this river hereabouts and the M4 toward the south, with a number of towns also encircling the hill, including Rhydaman (Ammanford), Pontarddulais, Pontardawe and Glanaman.

The old fortification atop the hill is thought to date from the late 13^th century and is associated with the Marcher Lords, today its earthwork system of ditches and embankments is still impressive, but where once its view would be unencumbered, today one looks out on the Mynydd y Betws Wind Farm which incorporates 15 turbines that are 110m (361ft) in height.

I’d often wondered what name would be most appropriate for this hill as those of Mynydd y Betws and Mynydd y Gwair have been presented on Ordnance Survey maps, with the position of the former consistently given on the upper northern part of the hill, and the latter on the upper southern part of the hill.  However, it is the Tithe map that delineates the land boundary of each and also names the central land taking in the summit of this hill as Mynydd Penlle’rcastell.

Today I was out on a bagging road trip with Suzanne, a good friend for many a year and who was house sitting for one of her friends in Caerfyrddin (Carmarthen) for the week.  If wanting easy access to the summit of Mynydd Penlle’rcastell a minor road crosses the hill in a north to south direction and at its high point there is sufficient space to park one or two cars, and with six hills planned for the day we opted for this easy access route.

Whilst heading east driving toward the hill dark shower clouds hung over it, and although the westerly breeze pushed these forever inland a darkened sky met us when we pulled up at the top of the minor road crossing the hill.

A narrow path led across the grassland toward the earthworks of Penlle’rcastell and this passed within a few metres of where LIDAR analysis places two points that vie for the summit position of this hill, and as Suzanne headed toward the ditches and embankments I used the Trimble as a hand-held device and zeroed in to the first of these two positions.

LIDAR image of the summit of Mynydd Penlle'rcastell

Suzanne heading toward the remains of Penlle'rcastell

Once the Trimble was gathering data I joined my bagging accomplice and investigated the ruined fortification.  During this an occasional light shower sped across the hill with the rain no more than spots brought on the breeze, and with a brightening forecast for late morning and afternoon it looked as if our timing on this hill was perfect.

Gathering data at one of two points surveyed for the summit position of Mynydd Penlle'rcastell

With one data set gathered and stored I positioned the Trimble at the second point that LIDAR indicates for the high point of this hill and gathered another data set.  Once data were stored I packed the equipment away and we turned toward my car and walked the short distance back to the minor road, next stop; Mynydd Sylen (SN 515 080).

Survey Result:

Mynydd Penlle’rcastell (significant name change)

Summit Height:  373.3m (converted to OSGM15)

Summit Grid Reference:  SN 66498 09531

Bwlch Height:  166.4m (LIDAR)

Bwlch Grid Reference:  SN 69945 09589 (LIDAR)

Drop:  206.9m

Dominance:  55.42%

For further details please consult the Trimble Survey Spreadsheet

Mapping Mountains – Hill Reclassifications – 100m Twmpau

Warren Wood (SN 600 190) – 100m Twmpau reclassified to 100m Sub-Twmpau

There has been a reclassification to the 100m Twmpau due to LIDAR analysis conducted by Myrddyn Phillips, with the criteria for this list being:

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.

When the original Welsh P30 hills were published on Geoff Crowder’s v-g.me website this hill was included in the main P30 list.  When the accompanying sub list was standardised, and interpolated heights also included this hill was listed with an estimated c 31m of drop, based on an estimated c 190m summit height and an estimated bwlch height of c 159m based on interpolation of 10m bwlch contouring between 150m – 160m on the Ordnance Survey 1:25,000 Explorer map.  The drop value was re-assessed when the Ordnance Survey Interactive Coverage Map became available online via the Grograph website, this mapping has contour intervals at 5m for this hill, and the drop value was again estimated to be c 31m.

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

The name of the hill is Warren Wood and it is adjoined to the Mynydd Sylen group of hills, which are situated in the western part of South Wales (Region C, Sub-Region C1), and it is positioned with the B 4300 road to the north, the A 476 road to the east, and has the town of Llandeilo towards the north-east.

If wanting to visit the summit of the hill permission to do so should be sought as it is not a part of designated open access land, for those wishing to do so the easiest access is from a minor road to the west and south.

The reclassification of Warren Wood to 100m Sub- Twmpau status is due to LIDAR analysis conducted by Myrddyn Phillips.  The LIDAR (Light Detection & Ranging) technique produced highly accurate height data that is now freely available for much of England and Wales. 

LIDAR summit image of Warren Wood

LIDAR bwlch image of Warren Wood

The 1m DTM LIDAR analysis gives the hill the following details:

Name:  Warren Wood

Summit Height:  189.4m

Summit Grid Reference:  SN 60037 19085

Bwlch Height:  160.4m

Bwlch Grid Reference:  SN 59229 18910

Drop:  28.95m

Therefore, the 189.4m LIDAR analysis for the summit position at SN 60037 19085 and the 160.4m LIDAR analysis for the bwlch position at SN 59229 18910 gives this hill 28.95m of drop, which is insufficient for continued 100m Twmpau status.

The full details for the hill are:

Group:  Mynydd Sylen

Name:  Warren Wood

OS 1:50,000 map:  159

Summit Height:  189.4m (LIDAR)

Summit Grid Reference:  SN 60037 19085 (LIDAR)

Bwlch Height:  160.4m (LIDAR)

Bwlch Grid Reference:  SN 59229 18910 (LIDAR)

Drop:  28.95m (LIDAR)

Myrddyn Phillips (October 2018)

Mapping Mountains – Trimble Surveys – Mynydd Sylen

31.07.18  Llain Fawr (SN 428 202)

Llain Fawr (SN 428 202)

Llain Fawr is only a small heighted hill, but it is easily picked out from adjacent hills to its south which I had visited earlier in the day.  It sits above the small community of Llangunnor, its Church and Chuch Farm and the car park for the Church gives easy access to its summit.

Prior to visiting I’d analysed this hill’s summit and bwlch via LIDAR and come prepared with the ten figure grid reference for its summit.

LIDAR image of the summit of Llain Fawr

LIDAR image of the bwlch of Llain Fawr

It was only a few minutes’ walk up the remainder of the car park to a gate which gives access to the top field, a vehicle track led across the south-eastern flank of the field and I followed this until near the boundary hedge close to the summit of the hill.

Once the Trimble was positioned atop my rucksack to give it elevation above its immediate surrounds and the 0.1m accuracy level attained before data should be logged, I pressed ‘Log’ and stood back looking south toward the hills I had visited earlier in the day.

The sound of the beep, beep, beep of the equipment as each datum point is collected quietly blew in the afternoon’s breeze as I stood looking out at a land that I had not previously visited.  This part of P30 bagging when new land is visited signifies a form of investigation and for me this brings a sense of fulfilment.

Gathering data at the summit of Llain Fawr

The Trimble set-up position at the summit of Llain Fawr

Once the allotted data were gathered and stored I packed the equipment away and headed back to my car to change out of my walking gear and drive the short distance to Caerfyrddin (Carmarthen), where I was staying the night with a friend who was house sitting for one of her friends.  Tomorrow we had planned a six hill bagging road trip to enjoy.

Survey Result:  

Llain Fawr (significant name change)

Summit Height:  80.8m (converted to OSGM15)

Summit Grid Reference:  SN 42855 20265

Bwlch Height:  23.0m (LIDAR)

Bwlch Grid Reference:  SN 42905 19831 (LIDAR)

Drop:  57.8m (Trimble summit and LIDAR bwlch)

Dominance:  71.49% (Trimble summit and LIDAR bwlch)

For further details please consult the Trimble Survey Spreadsheet

UKHillwalking - Moving Mountain Summits

Foel Cedig – Relocation of Marilyn, Hump, Simm, Hewitt, Pellennig, Uchaf and Nuttall summit from Cyrniau Nod

UKHillwalking Article

UKHillwalking recently published an article on the summit relocation of Cyrniau Nod to Foel Cedig.  The original article and a link to it on the UKHillwalking website appear below.

Moving Mountain Summits

Prolific amateur hill surveyor Myrddyn Phillips 'discovers' a new summit for one of the Berwyn mountains of North Wales...

Foel Cedig stands out from afar as it has a small grassy knoll which gives the hill the impression of having a slightly raised summit - a contrast to its heather bound neighbours, the majority of which comprise high whale backed ridges that have rounded summits almost indistinguishable from the moor. However, the hill was thought to have little prominence as it is given a map height of 666m, whilst the neighbouring Cyrniau Nod has always been accepted as higher because of its 667m map height.

Foel Cedig on left with the deposed Cyrniau Nod on the right

These two hills, Foel Cedig and Cyrniau Nod, form a part of the great swathe of wild land that comprise the Berwyn. This extensive range of hills stretches from the Afon Dyfrdwy (River Dee) as it passes the confines of Corwen and Llangollen in the north, all the way south to the hills above Dinas Mawddwy and the infant Afon Dyfi (River Dovey).

As Cyrniau Nod is higher according to Ordnance Survey maps it has always been considered the prioritised summit of these two hills, and with a prominence of 179m and a height over 600m it is both relatively high and relatively prominent. As such it is listed as a Marilyn, Hump, Simm, Hewitt, Uchaf and Nuttall:

• Marilyn: British hills with 150m minimum drop irrespective of their height
• Hump: British hills with 100m minimum drop irrespective of their height
• Simm: British hills with 600m minimum height and 30m minimum drop
• Hewitt: English, Welsh and Irish hills with 2,000ft (609.6m) minimum height and 30m minimum drop
• Uchaf: This is the working title for a list comprising Welsh hills with 500m minimum height and 15m minimum drop
• Nuttall: English and Welsh hills with 2,000ft (609.6m) minimum height and 15m minimum drop

However, the surveying method of photogrammetry that ascertained the map height of Foel Cedig has a margin of uncertainly of +/- 3m, whilst the map height given Cyrniau Nod is based on a series of levelled heights which are more accurate. So could Foel Cedig in fact be higher than Cyrniau Nod? There was only one way to find out; visit both hills and accurately survey their summits.

It was a breezy morning setting off from the high road at it passes over the upper part of Cwm Hirnant to the west of these hills, and with heavy overnight rain and a forecast of morning showers I did not want to linger.

A track skirting the summits of a number of heather bound hills eases access, and I used this to make forays to each as I slowly made surveying progress to the prioritised surveys of Foel Cedig and Cyrniau Nod.

To survey these hills I used a Trimble GeoXH 6000 which is a GNSS receiver capable of measurement to within and better than 0.1m in height. As it has an internal antenna and only weighs 2lb it does not require an additional antenna, pole and tripod, therefore its portability and its accuracy over a five minute period of data collection are huge advantages when out on the hill.

The track across the moor leading toward Foel Cedig

The summit of Foel Cedig comprises an attractive knoll with exposed rock and is easily distinguished from surrounding ground. To give the Trimble elevation above its immediate surrounds I usually place the equipment on top of my rucksack, using this as an improvised tripod, and this is what I did for each summit.

Having taken a ten minute data set I continued through the heather and bog toward Cyrniau Nod. John Barnard and I had surveyed this hill with a level and staff for summit position in June 2014, and once at its summit this is where I placed the Trimble and gathered another ten minute data set. So what of the results?

The Trimble GeoXH 6000 results are given below:

• Foel Cedig – 667.4m summit at SH 98170 28327
• Cyrniau Nod – 666.2m summit at SH 98847 27920

Therefore, as Foel Cedig is 1.2m higher than Cyrniau Nod, the prioritised summit is relocated to the attractive rock exposed knoll of Foel Cedig.

This information may be met with gasps of woe by any hill walker who has visited this area to bag either a Marilyn, Uchaf or Nuttall, as except for those who purposely diverted to visit Foel Cedig with the understanding that its map height has such a margin of uncertainty, the summit would no doubt have been bypassed.

Alan Dawson, the author of the Marilyns, Hewitts and Simms has been informed of this result and accepted the summit relocation, as have the authors of the Uchafion list, Aled Williams and Myrddyn Phillips (that's me!); will John and Anne Nuttall follow suit? We'll have to wait and see.

For the original article published on the UKHillwalking website