Wednesday, 19 December 2018

Mapping Mountains – Hill Reclassifications – 30-99m Twmpau


West Park (SR 940 990) – 30-99m Sub-Twmpau reclassified to 30-99m Twmpau

There has been confirmation of a reclassification to the list of 30-99m Twmpau due to LIDAR analysis conducted by Myrddyn Phillips.

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

30-99m Twmpau - Welsh hills at or above 30m and below 100m in height with 30m minimum drop, with an accompanying sub list entitled the 30-99m Sub-Twmpau with the criteria for this sub category being all Welsh hills at or above 30m and below 100m 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 West Park

When the original Welsh P30 hills were published on Geoff Crowder’s v-g.me website this hill appeared in the accompanying Hills to be surveyed sub list as it did not meet the criteria then used for the main P30 list; however this sub list has now been standardised and interpolated heights also included in the main P30 and the accompanying sub list.

When this list was standardised and interpolated heights also included this hill was listed with an estimated c 30m of drop, based on an estimated c 82m summit height and an estimated bwlch height of c 52m based on 5m contouring on the Ordnance Survey 1:25,000 Explorer map.

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

The bounded land where the summit of this hill is situated is named as West Park on the Tithe map, and this is the name the hill is now listed by, and it is adjoined to the Brandy Hill group of hills, which are situated in the south-western part of Mid and West Wales (Region B, Sub-Region B4), and is positioned between the B roads of the 4320 to the north and the 4319 to the south, and has the town of Penfro (Pembroke) towards the north-east.

If wanting to visit this 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 most convenient approach would be from a minor road to the west of the summit.

The confirmation of this reclassification 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. 

The LIDAR analysis gives the hill the following details:


Name:  West Park

Summit Height:  81.7m

Summit Grid Reference:  SR 94023 99001

Bwlch Height:  51.3m

Bwlch Grid Reference:  SR 94747 99655

Drop:  30.4m


Therefore, the 81.7m LIDAR analysis for the summit position at SR 94023 99001 and the 51.3m LIDAR analysis for the bwlch position at SR 94747 99655 gives this hill 30.4m of drop, which confirms its 30-99m Twmpau status.


The full details for the hill are:

Group:  Brandy Hill

Name:  West Park

OS 1:50,000 map:  158

Summit Height:  81.7m (LIDAR)

Summit Grid Reference:  SR 94023 99001 (LIDAR)

Bwlch Height:  51.3m (LIDAR)

Bwlch Grid Reference:  SR 94747 99655 (LIDAR)

Drop:  30.4m (LIDAR)


Myrddyn Phillips (December 2018)






Tuesday, 18 December 2018

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


Mynydd Pencarreg (SN 575 432) – Lesser Dominant addition

There has been an addition to the listing of Y Trechol – The Dominant Hills of Wales due to a combination of LIDAR analysis conducted by Aled Williams and a summit survey with the Trimble GeoXH 6000 conducted by Myrddyn Phillips, with the latter taking place on the 31st July 2018.

The summit of Mynydd Pencarreg (SN 575 432)

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 addition Welsh P30 hills whose prominence is 33.33% or more and below 50% 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 3rd December 2015.

Prior to LIDAR analysis and the summit survey with the Trimble GeoXH 6000 this hill was listed with an estimated c 138m of drop based on the 415m summit height given to a triangulation pillar that appears on the Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer map and an estimated bwlch height of c 277m based on interpolation of bwlch contouring between 270m – 280m on these two maps and partial 5m contouring that appears on the Ordnance Survey Interactive Coverage Map hosted on the Geograph website, with these values giving this hill 33.25% dominance.
                               
The name of the hill is Mynydd Penycarreg and it is the highest hill in own grouping of hills, which are situated in the central part of Mid and West Wales (Region B, Sub-Region B2), and it is positioned between the B 4337 road to the south-west and the A 482 road towards the north-east, and has the town of Llanbedr Pont Steffan (Lampeter) towards the north.

As the summit of the hill is a part of designated open access land permission to visit does not have to be sought, however this open access land is almost an island without any public footpaths leading to it and with only one recognised access point from a minor road to the south-west of the summit.

The addition of Mynydd Pencarreg to Lesser Dominant status is due to LIDAR analysis conducted by Aled Williams coupled with a Trimble GeoXH 6000 summit survey 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.

The survey with the Trimble produced a summit height of 414.9m (converted to OSGM15), whilst the LIDAR analysis produced a bwlch height of 276.2m, with these values giving this hill 138.7m of drop and 33.43% dominance, which confirms its addition to Lesser Dominant status.

The Trimble GeoXH 6000 gathering data at the summit of Mynydd Pencarreg


The full details for the hill are:

Group:  Mynydd Pencarreg

Name:  Mynydd Pencarreg

OS 1:50,000 map:  146

Summit Grid Reference:  SN 57560 43215

Summit Height:  414.9m (converted to OSGM15)

Bwlch Grid Reference:  SN 60011 44082 (LIDAR)

Drop Summit to Bwlch:  138.7m (Trimble summit and LIDAR bwlch)

Drop Bwlch to ODN:  276.2m (LIDAR)

Dominance:  33.43% (Trimble summit and LIDAR bwlch)


For details on the summit survey of this hill

Myrddyn Phillips (December 2018)






Monday, 17 December 2018

Mapping Mountains – Trimble Surveys – Glyderau


01.10.18  Bryniau (SH 579 711)  

Bryniau (SH 579 711)

To the immediate south-east of Bangor the small heighted ridge overlooking the city leads south-westward toward higher ground in the Glyderau.  Ordnance Survey maps give the name of Bangor Mountain to a part of this ridge, with this name consistently applied on the map to its northern part, the position of this name is also substantiated by local enquiry.  This map name would no doubt be known as Mynydd Bangor by locals. 

I’d spent the early afternoon analysing the summit and bwlch of this hill via LIDAR and now wanted to visit, it remained one of the few P30s in this part of Eryri that I had not been up and whilst doing so I hoped to meet the local farmer and make enquiries about its name.

The summit area of this hill has a golf course on its western side, with a triangulation pillar placed near to what is now the 14th hole.  Between the trig pillar and the summit is a large covered reservoir which is well protected by high metal fencing, with the high point of the hill on the eastern side of this and close to a high mast.  As one would expect the golf course is well manicured, but between it and the summit is a mass of gorse and a double barb wired fence raised on an old stone wall.  I’d read reports of difficulty even getting to the trig from certain directions and therefore opted to approach from the north-west on a track leading toward the mast.

The well protected covered reservoir with the summit of the hill close to the high mast

I left my car on the lane that leads up toward the track and was met by a sign proclaiming ‘Private Land, no public right of way’ pinned to the access gate, I took a photograph and quietly continued up the track.

The track leads to the old farm house of Bryniau, with the summit of the hill just behind the house, foolishly I decided to bi-pass the house and follow another track on the right which led to a high and collapsed metal fence which I walked over, this led on to the golf course.

Once on the manicured fairway the view to the west opened up looking down on to the houses of Bangor, and across to Penrhos Garnedd, which I’d surveyed the day before.

I followed a perimeter path heading south, to my left was the covered reservoir with its high metalled fence and beyond was the high mast with the summit of the hill close by, and between me and it was a mass of gorse and bramble.

Although I had not planned on visiting the trig pillar the perimeter path led me toward it, I now had little option for further progress toward the summit, other than venture in to the gorse and bramble to a double barb wired fence positioned on top of a raised old wall come embankment.  As I get older I am more aware of the hazards that barb wired fences can course to a hill walker, and this one in particular was screaming out to be careful as one misplaced lunge could result in a horrible bloodied mess.

The trig pillar

I eventually landed unceremoniously on the other side of the fence and proceeded on terra firma through gaps in the gorse to the summit of the hill, which is placed on a grassy knoll under a tree.

Once the Trimble was set up I waited for it to achieve its 0.1m accuracy level before data should be logged and watched five sheep graze their way from the wooded copse behind me and onward to more juicy morsels amongst the gorse.

It took ten minutes or more for the Trimble to reach its 0.1m accuracy level, and once it did I pressed ‘Log’ and stood a few metres away from it admiring the view to the west as the sun slowly crept ever lower under an immense straight lined high cloud bank that cut across the sky.

The immense straight-lined cloud bank that quickly pushed inland as I watched from the summit of Bryniau

As the sun slowly emerged under the cloud the summit was lit with a magical glow illuminating the land.  I knew this would only last for a short time as when intense evening colour arrives it can then depart quickly, usually this lasts no more than 30 minutes or so, but it’s always a pleasure to be out on the hill at this time of day watching the play of light and bathed in its glow.

I was in no rush to leave and wanted to savour the light, away to the east the high Eryri peaks were back-dropped by grey sky and all were on display, with the Carneddau stretched out leading to the Glyderau and Tryfan squeezed in at the head of Nant Ffrancon.  I could easily of stood and stared until the last ebb of light turned the scene to dusk, but needed to get down to visit my brother in Ysbyty Gwynedd, and if time permitted to also find the local farmer at Bryniau.

The Carneddau

Yr Elen and Carnedd Llywelyn

Once the Trimble had gathered and stored 15 minutes of data I closed it down, packed it away and walked the short distance down the track to the old farm house of Bryniau, where its tenant kindly directed me to the series of old barns where James Brown; the local farmer, and a colleague were working.

The Trimble GeoXH 6000 gathering data at the summit of Bryniau

The Trimble set-up position at the summit of Bryniau

Having explained by interest in James’ hill we headed back to its summit, James explained that the hill does not have an individual name and that Mynydd Bangor is much lower on this ridge and does not apply to this hill, and that the land is a part of, and also known as Bryniau. 

James at the summit of Bryniau

As James walked the short distance back down the grassed and gorse laden upper slopes toward the track, I lingered on the summit for a last few minutes watching the sun sink in to the sea as an oranged glow emanated its surrounds.

Sunset from the summit of Bryniau


Survey Result:



Bryniau (significant name change)

Summit Height:  117.6m (converted to OSGM15)

Summit Grid Reference:  SH 57971 71196 (summit relocation confirmed)

Bwlch Height:  87.4m (LIDAR)

Bwlch Grid Reference:  SH 57748 70845 (LIDAR)

Drop:  30.1m (Trimble summit and LIDAR bwlch) (100m Sub-Twmpau reclassified to 100m Twmpau)

Dominance:  25.63% (Trimble summit and LIDAR bwlch)






Sunday, 16 December 2018

Mapping Mountains – Summit Relocations – 30-99m Twmpau and Y Trechol – The Dominant Hills of Wales


Pwlldu Head (SS 569 865)

There has been a Summit Relocation to a hill that is listed in the 30-99m Twmpau and Y Trechol – The Dominant Hills of Wales, with the summit height, drop and status of the hill being confirmed by LIDAR analysis conducted by Myrddyn Phillips.

LIDAR image of Pwlldu Head

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

30-99m Twmpau - Welsh hills at or above 30m and below 100m in height with 30m minimum drop, with an accompanying sub list entitled the 30-99m Sub-Twmpau with the criteria for this sub category being all Welsh hills at or above 30m and below 100m 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.

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 addition Welsh P30 hills whose prominence is 33.33% or more and below 50% 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 3rd December 2015.

The name of the hill is Pwlldu Head, and it is adjoined to the Gŵyr group of hills, which are situated in the western part of South Wales (Region C, Sub-Region C1), and it is positioned overlooking the south Wales coast, and has the village of Melin y Parc (Parkmill) towards the north-west.

As the summit of the hill is a part of open access land it can be approached from most directions, with the open access land stretching to the north-west and north north-east of the summit and public footpaths approaching this land and that of the summit from the north.

Prior to LIDAR analysis this hill was listed with 35m of drop based on the 97m height given to a triangulation pillar positioned at SS 57003 86690 and the 62m bwlch spot height that appear on the Ordnance Survey 1:25,000 Explorer map, and it is the position of the triangulation pillar that had been listed for that of the summit.

LIDAR summit image of Pwlldu Head

The summit height produced by LIDAR analysis is 97.6m at SS 56933 86561 and its position in relation to that previously given comes within the parameters of the Summit Relocations used within this page heading, these parameters are:

The term Summit Relocations applies to any listed hill whose summit meets the following criteria; where there are a number of potential summit positions within close proximity and the highest point is not where previously given, 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, or when the summit of the hill is in a different field compared to where previously given, or when the natural and intact summit of a hill is confirmed compared to a higher point such as a raised field boundary that is judged to be a relatively recent man-made construct.  As heights on different scaled Ordnance Survey maps are not consistent the height given on the 1:25,000 Explorer map is being prioritised in favour of the 1:50,000 Landranger map for detailing these relocations.

The summit height produced by LIDAR analysis is 97.6m and is positioned at SS 56933 86561, this position is not given a spot height on contemporary Ordnance Survey maps and is approximately 130 metres south south-west from where the 97m spot height adjoined to the triangulation pillar appears on the Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer map.  

The Ordnance Survey Interactive Coverage Map hosted on the Geograph website showing the summit position in relation to where the trig pillar is positioned
 

The full details for the hill are:

Group:  Gŵyr

Name:  Pwlldu Head

OS 1:50,000 map:  159

Summit Height:  97.6m (LIDAR)

Summit Grid Reference (new position):  SS 56933 86561 (LIDAR)

Bwlch Height:  62.2m (LIDAR)

Bwlch Grid Reference:  SS 56191 88507 (LIDAR) 
 
Drop:  35.5m (LIDAR)

Dominance:  36.32% (LIDAR)


Myrddyn Phillips (December 2018)




Saturday, 15 December 2018

Mapping Mountains – Hill Reclassifications – Y Trichant


Cwm Faerdy Bank (SO 078 695) – Sub-Trichant reclassified to Trichant

There has been confirmation of a reclassification to the list of Y Trichant, with this initiated from LIDAR analysis and then confirmed by a Trimble GeoXH 6000 survey conducted by Myrddyn Phillips, with the lattet taking place on the 10th July 2018.

Cwm Faerdy Bank (SO 078 695)

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

Y Trichant – 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 its renaming appearing on Mapping Mountains on the 13th May 2017.

When the original Welsh P30 hills were published on Geoff Crowder’s v-g.me website this hill appeared in the accompanying Hills to be surveyed sub list as it did not meet the criteria then used for the main P30 list; however this sub list has now been standardised and interpolated heights also included in the main P30 and the accompanying sub list.

When this list was standardised and interpolated heights also included this hill was listed with an estimated c 30m of drop, based on the 302m spot height that appears on the Ordnance Survey 1:25,000 Explorer map and an estimated bwlch height of c 372m based on interpolation of bwlch contouring between 270m – 280m.  These details were re-examined when the Ordnance Survey Interactive Coverage Map hosted on the Geograph website became available online and the drop value was then amended to c 31m.

The name of the hill is Cwm Faerdy Bank, and this was derived from local enquiry, and it is adjoined to the Pegwn Mawr range of hills which are situated in the north-eastern part of Mid and West Wales (Region B, Sub-Region B1), and it is positioned with the Clywedog Brook to its west and the Afon Ieithon (River Ithon) to its east, and has the small community of Abaty Cwm-hir (Abbeycwmhir) towards the north-west. 

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 a public footpath approaches the hill from the north and east with the continuation of a track from where these footpaths meet leading toward the summit of the hill.

The confirmation of the reclassification of Cwm Faerdy Bank to Y Trichant 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 image of Cwm Faerdy Bank

The LIDAR analysis gives the hill the following details:


Name:  Cwm Faerdy Bank

Summit Height:  302.2m

Summit Grid Reference:  SO 07843 69513

Bwlch Height:  269.8m

Bwlch Grid Reference:  SO 08305 69665

Drop:  32.3m


Therefore, the 302.2m LIDAR analysis for the summit position at SO 07843 69513 and the 269.8m LIDAR analysis for the bwlch position at SO 08305 69665 gives this hill 32.3m of drop, with the details from the Trimble GeoXH 6000 survey being 302.3m (converted to OSGM15) summit at SO 07842 69512 and 269.9m (converted to OSGM15) bwlch at SO 08304 69664, giving this hill 32.4m of drop which confirms its Trichant status.

The Trimble GeoXH 6000 gathering data at the summit of Cwm Faerdy Bank

The full details for the hill are:

Group:  Pegwn Mawr

Name:  Cwm Faerdy Bank

OS 1:50,000 map:  136, 147

Summit Height:  302.3m (converted to OSGM15)

Summit Grid Reference:  SO 07842 69512

Bwlch Height:  269.9m (converted to OSGM15)

Bwlch Grid Reference:  SO 08304 69664

Drop:  32.4m (converted to OSGM15)



Myrddyn Phillips (December 2018)