Mapping Mountains – Hill Reclassifications – 30-99m Twmpau

Yr Orsedd (SH 299 270) – 30–99m Sub-Twmpau reclassified to 30-99m Twmpau

There has been confirmation of a Hill Reclassification to the list of 30-99m Twmpau, with the summit height, its location, the drop and status of the hill confirmed by LIDAR analysis, and a subsequent summit survey with the Trimble GeoXH 6000 conducted by Myrddyn Phillips, with the latter taking place on the 3^rd October 2018.

Yr Orsedd (SH 299 270)

The criteria for the list 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.

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 with drop values and interpolated heights also included in the main P30 and the accompanying sub list.

When this list was standardised with interpolated heights and drop values included this hill was listed with c 31m of drop based on the 64m summit spot height positioned at SH 295 266 on the Ordnance Survey 1:25,000 Explorer map and an estimated bwlch height of c 33m based on interpolation of 10m bwlch contouring.

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

The details for this hill were reassessed when the Ordnance Survey Interactive Coverage Map hosted on the Geograph website became available online, and this map has a 66m spot height at SH 299 270 which is adjoined to the hill to the north-east, which only has an uppermost 60m ring contour on the 1:25,000 Explorer map.  Therefore the summit position of the listed hill was relocated and its drop value increased accordingly, with the Interactive Coverage Map also giving the south-westerly hill a second 64m map heighted summit.

Extract from the Ordnance Survey Interactive Coverage Map hosted on the Geograph website

Prior to the Trimble GeoXH 6000 summit survey this hill and its adjoining south-westerly 64m twin map heighted hill were analysed via LIDAR, and this confirmed that the north-easterly summit is the higher.

The locally known name of the higher summit is Yr Orsedd, whilst the lower south-westerly summit is known locally as Bryn Tŷ Newydd, and it is adjoined to the Pen Llŷn group of hills, which are situated in the western part of North Wales (Region A, Sub-Region A1), and the hill is encircled by minor roads with the coast to its south-west and east, and has the village of Abersoch towards its north-east.

Bryn Tŷ Newydd, the old listed summit to the south-west

As the summit of this hill is not a part of designated open access land permission to visit should be sought, for those wishing to do so the easiest approach is via the east using gates to access the summit.

The confirmation of the reclassification of Yr Orsedd to 30-99m Twmpau status is due to LIDAR analysis and a summit survey with the Trimble GeoXH 6000 conducted by Myrddyn Phillips, resulting in a 67.5m summit height and a 32.0m bwlch height, with these values giving this hill 35.4m of drop which is sufficient for it to be classified as a 30-99m Twmpau.

The Trimble GeoXH 6000 gathering data at the summit of Yr Orsedd

The full details for the hill are:

Group:  Pen Llŷn

Name:  Yr Orsedd

OS 1:50,000 map:  123

Summit Height:  67.5m (converted to OSGM15)

Summit Grid Reference:  SH 29952 27038

Bwlch Height:  32.0m (LIDAR)

Bwlch Grid Reference:  SH 29808 27337 (LIDAR)

 

Drop:  35.4m (Trimble summit and LIDAR bwlch)

For details on the summit survey of this hill

Myrddyn Phillips (February 2019)

Mapping Mountains – Significant Name Changes – 30-99m Twmpau and Y Trechol – The Dominant Hills of Wales

Yr Orsedd (SH 299 270)

There has been a Significant Name Change to a hill that is listed in the 30-99m Twmpau and Y Trechol – The Dominant Hills of Wales, with the summit height, its location, the drop and status of the hill confirmed by LIDAR analysis, and a subsequent summit survey with the Trimble GeoXH 6000 conducted by Myrddyn Phillips, with the latter taking place on the 3^rd October 2018.

The summit of Yr Orsedd (SH 299 270)

The criteria for the two listings that this name change 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 additional Welsh P30 hills whose prominence is between one third and half that of their absolute height, with the Introduction to the Mapping Mountains publication of this list appearing on the 3^rd December 2015.

The hill is adjoined to the Pen Llŷn group of hills, which are situated in the western part of North Wales (Region A, Sub-Region A1), and the hill is encircled by minor roads with the coast to its south-west and east, and has the village of Abersoch towards its north-east.

This hill was first listed in the Hills to be surveyed sub-list that accompanied the original Welsh 30-99m P30 list published on Geoff Crowder’s v-g.me website, under the invented name of Bryn Llanengan, with an accompanying note stating; Name from village to the North-West.

Bryn Llanengan

64m

SH296266

123

253

Name from village to the North-West

This hill was listed with a 64m summit height which is positioned at SH 295 266 and appeared as a spot height on the Ordnance Survey 1:25,000 Explorer map.  The details for this hill were reassessed when the Ordnance Survey Interactive Coverage Map hosted on the Geograph website became available online, and this map has a 66m spot height at SH 299 270 which is adjoined to the hill to the north-east, which only has an uppermost 60m ring contour on the 1:25,000 Explorer map.  Therefore the summit position of the listed hill was relocated and its drop value increased accordingly, with the Interactive Coverage Map also giving the south-westerly hill a second 64m map heighted summit, and LIDAR analysis confirms that the north-easterly of these two hills is the higher.

The old listed summit that is known locally as Bryn Tŷ Newydd

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 use the name of a near village and put the word Bryn in front of it.  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

I visited this hill along with Aled Williams and on our way back to the car I took the opportunity to call at one or two houses hoping to be directed toward the local farmer.  A woman was on the drive of the second house we called out and she was the partner of Wyn Roberts, who had been on his quad bike in an adjacent field when we were on the summit.  Having explained our interest in the hill’s name we were directed down the road to where Wyn would soon re-appear on his quad bike after checking on his herd of cows.

After flagging Wyn down and introducing ourselves he explained that the hill we had visited is known as Yr Orsedd and the lower hill to the south-west, that was first listed as the qualifying P30 is known as Bryn Tŷ Newydd.

Wyn Roberts

Therefore, the name this hill is now listed by in the 30-99m Twmpau and Y Trechol – The Dominant Hills of Wales is Yr Orsedd, and this was derived from local enquiry.

The full details for the hill are:

Group:  Pen Llŷn

Name:  Yr Orsedd

Previously Listed Name:  Bryn Llanengan 

OS 1:50,000 map:  123

Summit Height:  67.5m (converted to OSGM15)

Summit Grid Reference:  SH 29952 27038

Bwlch Height:  32.0m (LIDAR)

Bwlch Grid Reference:  SH 29808 27337 (LIDAR)

 

Drop:  35.4m (Trimble summit and LIDAR bwlch)

Dominance:  52.52% (Trimble summit and LIDAR bwlch)

For details of the summit survey of this hill

Myrddyn Phillips (February 2019)

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

Yr Orsedd (SH 299 270)

There has been confirmation of 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, its location, the drop and status of the hill confirmed by LIDAR analysis, and a subsequent summit survey with the Trimble GeoXH 6000 conducted by Myrddyn Phillips, with the latter taking place on the 3^rd October 2018.

Yr Orsedd (SH 299 270)

The criteria for the two listings 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 additional Welsh P30 hills whose prominence is between one third and half that of their absolute height, with the Introduction to the Mapping Mountains publication of this list appearing on the 3^rd December 2015.

The name of the hill is Yr Orsedd, and this was derived from local enquiry, and it is adjoined to the Pen Llŷn group of hills, which are situated in the western part of North Wales (Region A, Sub-Region A1), and the hill is encircled by minor roads with the coast to its south-west and east, and has the village of Abersoch towards its north-east.

As the summit of this hill is not a part of designated open access land permission to visit should be sought, for those wishing to do so the easiest approach is via the east using gates to access the summit.

This hill was first listed in the Hills to be surveyed sub-list that accompanied the original Welsh P30 list published on Geoff Crowder’s v-g.me website, with a 64m summit height which is positioned at SH 295 266 and appeared as a spot height on the Ordnance Survey 1:25,000 Explorer map. 

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

When this list was standardised with interpolated heights and drop values included this hill was listed with c 31m of drop based on the 64m summit spot height and an estimated bwlch height of c 33m based on interpolation of 10m bwlch contouring, and the locally known name for this hill is Bryn Tŷ Newydd.

Bryn Tŷ Newydd (SH 295 265)

The details for this hill were reassessed when the Ordnance Survey Interactive Coverage Map hosted on the Geograph website became available online, and this map has a 66m spot height at SH 299 270 which is adjoined to the hill to the north-east, which only has an uppermost 60m ring contour on the 1:25,000 Explorer map.  Therefore the summit position of the listed hill was relocated and its drop value increased accordingly, with the Interactive Coverage Map also giving the south-westerly hill a second 64m map heighted summit.

Extract from the Ordnance Survey Interactive Coverage Map hosted on the Geograph website

Prior to the Trimble GeoXH 6000 summit survey this hill and its adjoining south-westerly 64m twin map heighted hill were analysed via LIDAR, and this confirmed that the north-easterly summit is the higher.

The height produced by the Trimble GeoXH 6000 survey to the summit of this hill is 67.5m and is positioned at SH 29952 27038, as opposed to the 64.2m LIDAR height for the higher of the two 64m Geograph summits to the south-west and which is positioned at SH 29571 26573.  This confirms the hill’s summit position compared to where previously listed, and it 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.

Therefore, the summit height produced by the Trimble GeoXH 6000 survey is 67.5m and is positioned at SH 29952 27038, this position is given a 66m spot height on the Ordnance Survey Interactive  Coverage Map hosted on the Geograph website and is approximately 550 metres north-east from where the previously listed summit is positioned.

The Trimble GeoXH 6000 gathering data at the summit of Yr Orsedd

The full details for the hill are:

Group:  Pen Llŷn

Name:  Yr Orsedd

OS 1:50,000 map:  123

Summit Height:  67.5m (converted to OSGM15)

Summit Grid Reference (new position):  SH 29952 27038

Bwlch Height:  32.0m (LIDAR)

Bwlch Grid Reference:  SH 29808 27337 (LIDAR)

 

Drop:  35.4m (Trimble summit and LIDAR bwlch)

Dominance:  52.52% (Trimble summit and LIDAR bwlch)

For details on the summit survey of this hill

Myrddyn Phillips (February 2019)

Mapping Mountains – Trimble Surveys – Yr Eifl

03.10.18  Yr Orsedd (SH 299 270)  

Yr Orsedd (SH 299 270)

Part of the fun of visiting a small heighted hill is the adventure of getting to its summit; this can involve all manner of clandestine manoeuvres and even when within reach of its all-important high point a profusion of undergrowth can add complication to the matter at hand.  Visiting these small heighted hills also gives opportunity to make local place-name enquiries as many of these hills do not possess a map name.

Having visited three near hills and gone on a bag of chips hunt for a lunch time snack Aled and I headed the short distance from Abersoch south-westward toward the small community of Llanengan, where two fields about 500 metres apart vie for the accolade of claiming P30 status.  The prestige of being classified as the P30 used to belong to the 64m map heighted south-westerly hill which is known locally as Bryn Tŷ Newydd, however eagle eyed map studiers spotted that the Ordnance Survey Interactive Coverage Map hosted on the Geograph website gives a 66m spot height to the north-easterly hill which is known locally as Yr Orsedd.

As LIDAR confirms Yr Orsedd as higher than Bryn Tŷ Newydd we only had the former on our radar to visit and Trimble today.  I parked my car to the east of the summit, toward the end of a road junction giving sufficient space for other cars to pass and away we went heading toward a gate which gave access to a manicured field leading toward the summit of the hill.

Aled heading toward the summit

Even from this approach the gorse on the upper part of the hill was on show and as we arrived at the boundary fence adjacent to the summit it looked positively evil.  Aled headed in to it first and easily found the high point, he stood on the summit amongst the gorse, chest high in the stuff, and this didn’t give me much hope for Trimble satellite reception.  I soon joined Aled and positioned the Trimble atop my rucksack giving it a semblance of elevation above its immediate surrounds, and stood back as it ebbed down to its 0.1m accuracy level before data should be logged.  This was attained remarkably quickly considering its position, and once gathering data I left it in situ for ten minutes.

Aled at the summit of Yr Orsedd

Gathering data at the summit of Yr Orsedd

As the Trimble gathered its allotted data I looked out toward Garn Fadrun, its scree laden slopes edged in a hint of afternoon sunshine.  To the south-west Bryn Tŷ Newydd shone back manicured green with a foreground of grazing cattle and Mynydd Cilan as backdrop.  Below us a quad bike buzzed around in the adjacent field, and we wondered if this was the local farmer, and if so he would probably be able to help with the name of the hill, but as I switched the Trimble off and packed it away he had driven off.

The Trimble set-up position at the summit of Yr Orsedd

The scree laden slopes of Garn Fadrun

The manicured grazing fields of Bryn Tŷ Newydd

We descended north from the summit and called at a house hoping to ask about the hill and its name, no one was in.  Undeterred I headed up the road toward the next house and Kate met us on her drive, once introductions and explanations had been given she explained that her partner; Wyn, was the farmer who we had seen on his quad bike and that he had headed down to Porth Neigwl (Hell’s Mouth) to feed the cattle.  Thanking Kate we went in search of Wyn.

I flagged Wyn down as he drove back up the road from Porth Neigwl and he told us the names for both hills; Yr Orsedd and Bryn Tŷ Newydd, the details of which will appear in a Significant Name Changes post, and after thanking Wyn for his time we headed north toward our next hill; Moel y Penmaen (SH 338 386).

Survey Result:

Yr Orsedd (significant name change)

Summit Height:  67.5m (converted to OSGM15, Trimble GeoXH 6000)

Summit Grid Reference:  SH 29952 27038 (Trimble GeoXH 6000) (summit relocation confirmed)

Bwlch Height:  32.0m (LIDAR)

Bwlch Grid Reference:  SH 29808 27337 (LIDAR)

Drop:  35.4m (Trimble GeoXH 6000 summit and LIDAR bwlch) (30-99m Sub-Twmpau reclassified to 30-99m Twmpau)

Dominance:  52.52% (Trimble GeoXH 6000 summit and LIDAR bwlch)

For further details please consult the Trimble Survey Spreadsheet