Mapping Mountains – Trimble Surveys – Y Berwyn

04.05.17  Bwlan (SH 946 255)

Bwlan (SH 946 255)

Bwlan sits on the east south-eastern ridge of Cefn Coch (SH 923 266) as it descends in to the wild heather moor.  It probably has few visitors, and yet it has a serene beauty the landscape of moor can only give, a wildness of openness where windswept land and the spring calling of Skylark is interspersed with distant views and a quality of peacefulness seldom experienced.

I’d visited Bwlan once before in May 2005 when I used a basic levelling technique (BLS) to determine its drop value, resulting in 51ft 6˝ (15.7m) of drop which was sufficient for its inclusion in the fledging list of the Yr Uchafion, however Bwlan has two options for its critical bwlch with an intermediary 523m map heighted bump between each, and as I’d only surveyed from one bwlch option to the top of this bump and then added 5m to the drop measurement to equate for the difference between the 523m spot height and the 528m spot height given to the summit of Bwlan, it meant the measurement was open to inaccuracy.

In recent months Aled Williams has been producing a multitude of results via LIDAR data, one being to Bwlan, resulting in a 526.1m summit and a 512.6m bwlch height, giving this hill 13.55m of drop.  However, the data produced by LIDAR only covered the ground for one of the two bylchau, therefore we wanted to visit this hill and Trimble each bwlch and the summit and compare the Trimble, LIDAR and the BLS data and confirm the status of Bwlan.

I met Aled in the car park at the northern end of Llyn Efyrnwy after he’d quickly visited the summit of Foel y Garnedd (SH 942 267), with a strong easterly wind blowing it gave land further west uninterrupted blue skies and as I waited for Aled the cloud cover began to break and by the time he had arrived and we’d got our boots on and driven up the road to the start of a forest track, the sky had turned a succulent blue.

It was good to be out with Aled again and we chatted away as we walked on the track past the old house of Fedw-ddu and continued up through the conifer forest on the southern edge of the Afon Nadroedd.  The track proved a convenient way to visit Bwlan and took us within a few metres of the 523m map heighted bump at SH 940 258.  Across the moor the high Aran dominated the view; they really are impressive hills, a bulk of a ridge firmly planted in the landscape, with moorland summits and ridges extending west from their high land.

The high Aran

The options for the bwlch position of Bwlan lay west and east of the 523m map heighted bump and as its summit was no more than a minute or so from the track we headed upward to Trimble it first.  As the Trimble gathered its data Aled headed off to assess the lay of land at the westerly bwlch that I had not surveyed 12 years ago and that LIDAR data does not cover.

Gathering data at the top of the 523m map heighted bump which came to 522.3m (converted to OSGM15)

Aled assessing the lay of land at the westerly bwlch

Once the Trimble was switched off and packed away I made my way down through the moor grass and heather and joined Aled at the westerly bwlch, we proceeded to take two data sets in the area of this bwlch, both in small channels on the hill to hill traverse.  During the time that the Trimble beeped away gathering its data we sat on the moor chatting as the breeze blew, Skylarks sang and the high Aran peered back from many a mile away.

An unusual view of Foel y Geifr, Trum y Gwragedd and Foel Goch with the slither of road crossing Cwm Hirnant on the right

Our next survey was the eastern bwlch which Aled had assessed using LIDAR data, and as I followed him, he used the Trimble as a hand-held GPS to take us to the position of the bwlch given by LIDAR, again this proved to be in a boggy channel.  Before setting the Trimble up we both assessed the lay of land and decided that with confidence of the LIDAR position that only one data set was required at the area of this bwlch.

Gathering data at the eastern bwlch which proved to be the critical one for Bwlan

Next stop was the summit and Aled repeated the process using the Trimble as a hand-held GPS, once on top we stomped around to find the firmest land that we judged to be the highest and I then proceeded to set the Trimble up to gather another data set.

Gathering data at the summit of Bwlan

Although the beauty of such hills as Bwlan can be in their solitude and openness, our planned descent route was past Pistyll Rhyd-y-meinciau, which is a series of waterfalls in the Afon Eiddew as it tumbles down toward Llyn Efyrnwy, and it was the prospect of visiting this waterfall that I suspected would add to the beauty of Bwlan.

Leaving the summit of Bwlan we walked south-eastward over rough moor to where a gate gave access on to high grazing land which had the comfort of grass and the prospect of easier walking for our descent, before doing so I took one last data set from the high point on the eastern end of the summit ridge of Bwlan which has a 525m map spot height.  As the Trimble gathered its data we lay in the sun and chatted about Aled’s upcoming stag night in Dublin, oh to be young again!

Once data were stored and the Trimble packed away we followed a fence down toward the ruin of Blaen-y-coed which in its time must have been a substantial building.  Below us the Afon Eiddew trickled on its descent, a wide stream discoloured with peat.  According to the map a path followed the steam on its northern side down to the forest corner where a track would take us back toward the car, however the path was almost non-existent and the further we progressed the bleached tussock grass grew larger, if a path existed we were not on it and although we scanned the ground ahead we could not see any sign of it.  It was then that we came across the first of five waterfalls, all radiant with the sun gleaming across their speckled water as it trickled downward on its never ending journey.

This house must have been a remote and desolate place to have once lived

The ruin of Blaen-y-coed above the Afon Eiddew

The Afon Eiddew below the ruin of Blaen-y-coed

As we approached the first waterfall we spotted a path on the southern side of the steam and looking down we saw that it continued, with just tussock grass and steepening slopes and no sign of a path on the northern side we decided to cross the stream, this proved a wise decision as the next half an hour was superb as one waterfall fell in to the next and the path zig-zagged its way down beside the stream giving access to each pool under each waterfall, it was a magical experience with the added bonus a small scramble down rock where the path had no other option than a vertical descent.

Aled crossing the Afon Eiddew

This is the waterfall below the point where we crossed the stream

Just one of a series of waterfalls that form Pistyll Rhyd-y-meinciau

Aled admiring one of the waterfalls

Pistyll Rhyd-y-meinciau

This photograph gives perspective as Aled looks up at one of the waterfalls

The path beside the waterfalls is highly recommended, it is narrow in places and sometimes ill-defined and has on occasion plummeting drops, but is well worth investigating.  As we left the last waterfall we continued downward to stepping stones across the river at the base of the falls and stopped and chatted with three people who were sitting in the sun.  As Aled talked with a woman who grew up in Blaenau Ffestiniog and now lived with her husband in Llanbrynmair, I talked with their friend who had travelled from London to be with them for a few days to get away from the chilled weather plaguing the east of England, during our conversation he told me that he sometimes practises faith healing and I half-jokingly mentioned my wonky right knee, a couple of minutes later and he was clasping my knee and working away faith healing its wonkiness.

Looking back toward Pistyll Rhyd-y-meinciau

It must be an impressive and frightening sight when in full spate

It was good to meet these people and enjoy conversation in the sunshine; leaving them we followed the well maintained path back toward my awaiting car as the southern bulk of Bwlan rose framed at the northern end of Llyn Efyrnwy, a great little hill, can’t wait for the Trimble results. 

Bwlan (SH 946 255)

Survey Result:

Bwlan

Summit Height:  525.9m (converted to OSGM15) (significant height revision)

Summit Grid Reference:  SH 94692 25540

Bwlch Height:  512.1m (converted to OSGM15)

Bwlch Grid Reference:  SH 94179 25714

Drop:  13.8m (Uchaf deletion confirmed)

Dominance:  2.62% 

 

For further details please consult the Trimble Survey Spreadsheet

Mapping Mountains - Y Pedwarau - The 400m Hills of Wales - Aran group of hills published

The Y Pedwarau list has been updated with the Aran group of hills

To access the Introduction to the Y Pedwarau Master List

To access the Master List for Y Pedwarau

Bagging the Welsh P30s – An Epic Hill List

An article published on the UKHillwalking website praising the virtues of P30s

Mapping Mountains – Hill Reclassifications – Y Trechol – The Dominant Hills of Wales

Pt. 258m (SH 647 065) – Lesser Dominant addition

There has been an addition to the listing of Y Trechol – The Dominant Hills of Wales which has resulted in this hill being added to the Lesser Welsh Dominant list.  The criteria for inclusion in this category of sub list is those Welsh P30 hills whose prominence is 33% or more and below 50% of their absolute height.

The details relating to this hill’s inclusion as a Lesser Welsh Dominant hill are retrospective as it appeared in the Tarennydd group of hills when published on the Mapping Mountains site on the 3rd December 2016.

The hill did not appear in the original listing of Y Trechol – The Dominant Hills of Wales as bwlch contours on Ordnance Survey maps of the day implied that the drop for the hill was only c 81m, with this based on the 258m summit spot height and an estimated bwlch height of 177m based on interpolation of bwlch contouring between 170m – 180m, these values would give the hill 31.40% Dominance which is insufficient for it to qualify for this sub list.

The hill is listed in the Tarennydd group and is placed in the Region of North Wales (Region A, Sub-Region A3) with its Cardinal Hill being Foel Wyllt (SH 624 042), and it is situated with the village of Abergynolwyn to its east and it rises above Dyffryn Dysynni and the Afon Dysynni which are to its north-west.

The hill is adjacent to Craig yr Aderyn (Bird’s Rock) and makes a good small circuit with its lower heighted neighbour, with both summits situated on designated open access land and public footpaths connecting with their summits from the valleys towards the north, west and east.

The hill is being listed under the point (Pt. 258m) notation as I do not know an appropriate name for it either from local enquiry or historical research, and it qualifies for Lesser Welsh Dominant status based on the 171m bwlch spot height that appears on the Ordnance Survey enlarged mapping hosted on the Geograph website, this when coupled with its 258m summit spot height gives the hill 87m of drop and 33.72% Dominance.

 

The full details for the hill are:

Group:  Tarennydd

Name:  Pt. 258m

Dominance:  33.72%

OS 1:50,000 map:  124

Summit Grid Reference:  SH 64705 06587

Summit Height:  258m

Drop Summit to Bwlch:  87m

Drop Bwlch to ODN:  171m 

Myrddyn Phillips (May 2017)

Mapping Mountains – Hill Reclassifications – Y Trechol – The Dominant Hills of Wales

Cefn (SH 721 004) – Lesser Dominant reclassified to Dominant

There has been a reclassification to the list of the Y Trechol – The Dominant Hills of Wales, with the summit height, bwlch height and their locations, the drop, dominance and status of the hill derived from detail on contemporary maps derived from Ordnance Survey data and subsequently confirmed by LIDAR analysis conducted by Myrddyn Phillips.

LIDAR image of Cefn (SH 721 004)

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

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 and this was derived from the Tithe map, and it is adjoined to the Tarren y Gesail group of hills, which are situated in the south-western part of North Wales (Region A, Sub-Region A3), and it is positioned with the A493 road to its north and the A487 road to its south, and has the town of Machynlleth towards the east.

After the original 100m height band of Welsh P30 hills published on Geoff Crowder’s v-g.me website were standardised and interpolated heights and drop values also included, this hill was listed with an estimated c 114m summit height, based on interpolation of its uppermost 110m ring contour, and the 59m bwlch spot height that appears on the Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer map, with these values giving this hill an estimated c 55m of drop and 48.25% dominance.

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

The details for this hill were re-assessed when the Ordnance Survey Vector Map Local hosted on the Geograph website and which was entitled the Interactive Coverage Map became available online.  This mapping had many spot heights not on other publicly available Ordnance Survey maps and for this hill it had a 119m summit spot height and when coupled with its 59m bwlch spot height, these values gave this hill 60m of drop and 50.42% dominance.

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 confirmation of the reclassification of this hill from Lesser Dominant status is due to LIDAR analysis, resulting in a 118.2m summit height and a 59.0m bwlch height, with these values giving this hill 59.2m of drop and 50.08% dominance, which is sufficient for Dominant status.    

The full details for the hill are:

Group:  Tarren y Gesail

Name:  Cefn

OS 1:50,000 map:  135

Summit Height:  118.2m (LIDAR)

Summit Grid Reference:  SH 72126 00402 (LIDAR)

Bwlch Height:  59.0m (LIDAR)

Bwlch Grid Reference:  SH 72569 00795 (LIDAR)

Drop:  59.2m (LIDAR)

Dominance:  50.08% (LIDAR)

Myrddyn Phillips (May 2017)

Mapping Mountains – Hill Reclassifications – Y Trechol – The Dominant Hills of Wales

Coed y Garth (SH 661 165) – Lesser Dominant addition (subsequently deleted)

Due to LIDAR analysis initially conducted by Chris Crocker and George Gradwell, and subsequently by Myrddyn Phillips, this hill has been deleted from the Lesser Dominant list as with 27.1m of drop it does not qualify.

There has been an addition to the listing of Y Trechol – The Dominant Hills of Wales which has resulted in the hill being added to the Lesser Welsh Dominant list.  The criteria for inclusion in this category of sub list is those P30 hills whose prominence is 33% or more and below 50% of their absolute height.

The details relating to this hill’s inclusion as a Lesser Welsh Dominant hill are retrospective as it appeared in the Cadair Idris group of hills when published on the Mapping Mountains site on the 3^rd November 2016.

The hill did not appear in the original listing of Y Trechol – The Dominant Hills of Wales as Ordnance Survey maps only gave the summit of the hill as having an uppermost ring contour of 80m, and with bwlch contouring between 50m – 60m the drop had been estimated as being below the minimum of 30m required for consideration for this list.

Since this list’s inception online mapping has improved and it is details on the Ordnance Survey enlarged mapping hosted on the Geograph website combined with the Harvey 1:25,000 Cadair Idris Superwalker map that has both bwlch and summit spot heights for this hill, with the former being 56m and the latter 87m, with these values giving 31m of drop and 35.63% Dominance.

The hill is listed in the Cadair Idris group and is placed in the Region of North Wales (Region A, Sub-Region A3) with its Cardinal Hill being Cadair Idris (SH 711 130), and it is situated between the small communities of Arthog to the south-west and Abergwynant to the east north-east.

As the hill is situated in conifer plantation a route to its summit may prove problematic, with access from the track that crosses its bwlch to the north-east possibly offering the quickest approach.

The name of the hill is Coed y Garth and it qualifies for Lesser Welsh Dominant status based on the 87m summit spot height on the Harvey 1:25,000 Cadair Idris Superwalker map and the 56m bwlch spot height on the Ordnance Survey enlarged mapping hosted on the Geograph website, with these values giving this hill 31m of drop and 35.63% Dominance.

   

The full details for the hill are:

Group:  Cadair Idris

Name:  Coed y Garth

Dominance:  35.63%

OS 1:50,000 map:  124

Summit Grid Reference:  SH 66100 16583

Summit Height:  87m

Drop Summit to Bwlch:  31m

Drop Bwlch to ODN:  56m 

Myrddyn Phillips (May 2017)

Mapping Mountains – Trimble Surveys – Worcestershire Beacon

30.04.17  Midsummer Hill (SO 759 375) and Eastnor Park (SO 752 378)     

Midsummer Hill (SO 759 375)

The Malvern Hills are justifiably popular and throngs of people descend to their well-maintained paths and shapely summits most weekends.  However, the lower summits on the southern extremity of the hill range give good walking with the benefit of fewer people, and this is where we headed to for a couple of hours this afternoon.

The main summit we planned on visiting is Midsummer Hill which has the remains of an ancient hill fort encircling its summit area, if weather and inclination permitted we also wanted to combine this hill with the lower summit to its north north-west that has an obelisk crowning its high point.

Both hills can be easily combined and we set off from the south where a free car parking area gives access to steep slopes heading in to deciduous woodland.  Although the sky was grey and the weather forecast predicted rain for later in the afternoon the woodland was bathed in serene blue as a multitude of blue bells cast their beautiful spell.  Late April and early May are a special time on the lower hills when slopes can become a myriad of succulent blues interspersed with new shooted greens as blue bells gather amongst spring’s new growth.

Blues and greens of the lower hills

The steep path gained height quickly beside masses of tangled brambles and undergrowth and proved a relatively easy way up toward the summit of Midsummer Hill.  During the wooded ascent an occasion trig was blown from overhead branches signalling the windy conditions on the top. 

Lou heading through the wood toward the summit of Midsummer Hill

The summit of Midsummer Hill is a few metres north of a memorial shelter that was built by Reverend H L Somers (who gave the hill to the National Trust) in memory of his son who was killed in the First World War.  As I assessed the lay of land to find the highest point of the hill, Lou took shelter on the leeward side crouching down out of the wind looking out toward the west and the continuation of our route to the obelisk.

Information board on the top of the memorial shelter close to the summit of Midsummer Hill

Once the Trimble was aligned with the high point of the hill and gathering data I stood back and hoped that no one else would visit the summit in the next five minutes, one couple approached, but they kept to the earthen embankment below the high point and soon disappeared from view, otherwise we had the summit to ourselves.

The summit of Midsummer Hill with the Trimble on the high point

The Eastnor Obelisk from Midsummer Hill

Gathering data at the summit of Midsummer Hill

Looking north to the higher Malvern Hills

By the time the Trimble had gathered its allotted five minutes of data the sky toward the west had turned a slate grey and with rain forecast for the afternoon we pressed on down the northern slopes of Midsummer Hill through woodland on a good path toward the hill’s connecting col.  Once at the col I set the Trimble up to gather data but the enclosed nature of where it was positioned did not encourage it to reach its 0.1m accuracy level before data should be logged, and after waiting ten minutes whilst directing a Landover and trailer and a few walkers to one side of where it was placed, I closed it off without any data having been collected and we made our way up toward the obelisk.

Heading down to the col

The Trimble positioned at the col waiting for the accuracy level to reach 0.1m before data should be logged

The obelisk is big and commands the southern extremity of the Malvern Hills, however our stay beside it was not long as the first rain drops were now falling and the western sky looked as if it was going to deposit lots of the wet stuff on us at any moment.

Approaching the Eastnor Obelisk

The higher Malvern Hills

Descending quickly to an earthen track we followed this until a gate gave access to open fields, these we followed back toward another track and then on to the car.  This descent proved a lot of fun as one in the party had concerns about killer rams and being off route and not on a main path, the pace of the descent and the fits of internal giggles thinking of killer rams made it hard for me to keep up, we arrived back at the car having dodged the rain which looked as if it had concentrated on the higher summits.  The walk proved a great couple of hours investigating the southern Malvern Hills whilst dodging the rain and the prospect of any rogue killer rams.

 ills.

Looking back toward the obelisk with the infamous field full of killer rams

Postscript: 

Since visiting these hills full LIDAR coverage is now available.  The LIDAR (Light Detection & Ranging) technique produced highly accurate height and positional data that is now freely available for England and Wales.  Consequently the numerical details for these hills have been analysed using this technique, resulting in LIDAR being used for the points not surveyed with the Trimble GeoXH 6000.

 

LIDAR image of Eastnor Psrk (SO 752 378)

Survey Result:

Midsummer Hill

Summit Height:  285.5m (converted to OSGM15, Trimble GeoXH 6000)

Summit Grid Reference:  SO 75957 37516 (Trimble GeoXH 6000)

Col Height:  204.5m (LIDAR)

Col Grid Reference:  SO 75666 37999 (LIDAR)

Drop:  81.0m (Trimble GeoXH 6000 summit and LIDAR col)

Dominance:  28.37% (Trimble GeoXH 6000 summit and LIDAR col)

Eastnor Park

Summit Height:  241.0m (LIDAR)

Summit Grid Reference:  SO 75227 37824 (LIDAR)

Col Height:  220.9m (LIDAR)

Col Grid Reference:  SO 75612 38173 (LIDAR)

Drop:  20.1m (LIDAR)

Dominance:  8.33% (LIDAR)

For further details please consult the Trimble survey spreadsheet