Mapping Mountains – Significant Height Revisions – Y Trichant – The 300m Hills of Wales

Foel Lus (SH 732 761)

There has been a Significant Height Revision 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 confirmed by LIDAR analysis conducted by Myrddyn Phillips.

Foel Lus (SH 732 761)

The criteria for the listing that this significant height revision 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.

The name the hill is listed by is Foel Lus and it is adjoined to the Carneddau group of hills, which are situated in the north-western part of North Wales (Region A, Sub-Region A1), and it is positioned with the A55 road to its north-west, and has the town of Penmaen-mawr towards the west and the town of Conwy towards the east north-east.  

This hill was included in the original 300m height band of Welsh P30 hills published on Geoff Crowder’s v-g.me website.  After the accompanying 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 an estimated c 60m of drop based on the 362m summit spot height that appears on the Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer map and an estimated bwlch height of c 302m based on contouring between 300m – 310m.

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

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.

LIDAR summit image of Foel Lus

The summit height produced by LIDAR analysis in comparison to the previously listed summit height comes within the parameters of the Significant Height Revisions used within this page heading, these parameters are:

The term Significant Height Revisions applies to any listed hill whose interpolated summit height and Ordnance Survey or Harvey map summit spot height has a 2m or more discrepancy when compared to the survey result produced by the Trimble GeoXH 6000 or analysis of data produced via LIDAR.  Also included are hills whose summit map data is missing an uppermost ring contour when compared to the data produced by the Trimble or by LIDAR analysis. 

Therefore, this hill’s new listed summit height is 360.0m and this was produced by LIDAR analysis.  This is not a dramatic revision in height compared to some revised heights and is 2.0m lower than the previous listed height of 362m which was derived from the summit spot height on the Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer maps.

ills of Wales, and are reproduced below@

The full details for the hill are:

Group:  Carneddau

Name:  Foel Lus

OS 1:50,000 map:  115

Summit Height (New Height):  360.0m (LIDAR)

Summit Grid Reference:  SH 73238 76184 (LIDAR)

Bwlch Height:  299.9m (LIDAR)

Bwlch Grid Reference:  SH 73386 75791 (LIDAR)

Drop:  60.1m (LIDAR)

Myrddyn Phillips (December 2019)

Mapping Mountains – Hill Reclassifications – Y Pedwarau – The 400m Hills of Wales

Bryn Crwn (SH 785 456) – 400m Sub-Pedwar addition

There has been an addition to the listing of Y Pedwarau - The 400m Hills of Wales due to analysis of data on the Geograph and WalkLakes websites, coupled with the 5m contouring on the OS Maps website.

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

Y Pedwarau – The 400m Hills of Wales.  Welsh hills at or above 400m and below 500m in height that have 30m minimum drop, accompanying the main Y Pedwarau list are five categories of sub hills, with this hill being added to the 400m Sub-Pedwar category.  The criteria for 400m Sub-Pedwar status being all Welsh hills at or above 400m and below 500m in height that have 20m or more and below 30m of drop.  The list is co-authored by Myrddyn Phillips and Aled Williams and is published on Mapping Mountains in Google Doc format.

The name the hill is listed by is Bryn Crwn, and it is adjoined to the Arenig group of hills, which are situated in the central part of North Wales (Region A, Sub-Region A3), and it is positioned with a minor road to its west and the B4407 road to its south and has Llyn Conwy to its north-west, and has the village of Penmachno towards the north and Ysbyty Ifan towards the north-east.

Prior to analysis of data on the Geograph and WalkLakes websites this hill was listed with an estimated c 19m of drop based on the 487m summit spot height that appears on contemporary Ordnance Survey 1:25,000 Explorer maps and an estimated bwlch height of c 468m based on interpolation of 10m contouring between 460m – 470m.

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

The details for this hill were re-assessed when the Ordnance Survey non-contour Vector Map Local hosted on the Geograph website and which is entitled the Interactive Coverage Map became available online.  This mapping has many spot heights not on other publicly available Ordnance Survey maps and importantly for this hill it has a 488m summit spot height positioned over 130 metres from where the 487m spot height appears on the Ordnance Survey 1:25,000 Explorer map indicating a higher position within the uppermost contour.

Another resource now available online is the WalkLakes website which hosts an interactive Ordnance Survey map originated from the Ordnance Survey Open Data programme.  This map has many spot heights not on other publicly available Ordnance Survey maps and for this hill’s summit the 488m spot height also appears in the same position as it does on the non-contour Vector Map Local hosted on the Geograph website.

Extract from the WalkLakes website

The details for this hill were also re-assessed when the OS Maps website became available online.  This is the replacement for OS Get-a-map and has contours at 5m intervals which are proving consistently more accurate compared to the 5m contours that sometimes appear on Ordnance Survey 1:25,000 Explorer maps and used to appear on the online Vector Map Local.  These re-assessments resulted in the hill being listed with an estimated c 20m of drop.

Extract from the OS Maps website

Therefore, the addition of Bryn Crwn to 400m Sub-Pedwar status is due to the analysis of data on the Geograph and WalkLakes websites with the estimated bwlch height confirmed via the 5m contouring on the OS Maps website.  Resulting in this hill being listed with a 488m summit height that appeared as a spot height on the Vector Map Local hosted on the Geograph website and appears as a spot height on the WalkLakes website and an estimated bwlch height of c 468m based on 5m contouring between 465m – 470m on the OS Maps website, with these values giving this hill an estimated c 20m of drop, which is sufficient for 400m Sub-Pedwar status.

The full details for the hill are:

Group:  Arenig

 

Name:  Bryn Crwn

OS 1:50,000 map:  115

Summit Height:  488m (spot height)

Summit Grid Reference:  SH 78585 45680 (spot height)

Bwlch Height:  c 468m (interpolation)

Bwlch Grid Reference:  SH 78573 46134 (interpolation)

Drop:  c 20m

For the additions, reclassifications and deletions to Y Pedwarau - The 400m Hills of Wales reported on Mapping Mountains since the May 2013 publication of the list by Europeaklist please consult the following Change Registers:

Y Pedwarau

Y Pedwarau – 400m Sub-Pedwarau

Y Pedwarau – 390m Sub-Pedwarau

Y Pedwarau – 390m Double Sub-Pedwarau

Myrddyn Phillips and Aled Williams (December 2019)

Y Pedwarau – The 400m Hills of Wales

Y Pedwarau – The 400m Hills of Wales

Haroldstreet Publication

During the latter part of 2019 we have reviewed the Y Pedwarau – The 400m Hills of Wales and updated the list with numerical data produced by LIDAR analysis and surveying with the Trimble GeoXH 6000.

The review also included re-examining the names of the hills with many updates now included within the list, both for their composition and their actual name.

Whilst reviewing the numerical data the hills listed by interpolated height and drop were also examined against the 5m contouring on the OS Maps website; this resulted in many numerical changes and some reclassifications.

This review has resulted in reclassifications to and from the main P30 list of Pedwar hills and additions and deletions to and from the accompanying sub lists.

The updated list is now available as an online tick list on the Haroldstreet website and we thank Phil Newby for hosting the Y Pedwarau – The 400m Hills of Wales.

The totals for each category and links to the Haroldstreet publication appear below:

Y Pedwarau - 448 hills

400m Sub-Pedwarau – 215 hills

390m Sub-Pedwarau – 37 hills

390m Double Sub-Pedwarau – 28 hills

Aled Williams and Myrddyn Phillips (December 2019)    

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

Yr Allt (SO 196 358) – Sub-Trichant reclassified to Trichant

There has been confirmation of 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 confirmed by LIDAR analysis conducted by Myrddyn Phillips.

LIDAR image of Yr Allt (SO 196 358)

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.

The name of the hill is Yr Allt and it is adjoined to the Mynyddoedd Duon group of hills which are situated in the eastern part of South Wales (Region C, Sub-Region C3), and it is positioned with minor roads to its west, north and east, with the A4078 road further to its west and the A438 road further to its north-west, and has the village of Aberllynfi (Three Cocks) towards the north-west.

When the original 300m height band of Welsh P30 hills were published on Geoff Crowder’s v-g.me website this hill was included in the Hills to be surveyed sub list that accompanied the main P30 list, as it was considered not to meet the criteria then used for the 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 an estimated c 31m of drop, based on an estimated c 335m summit height and an estimated c 304m bwlch height.

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

The details for this hill were re-examined when the Ordnance Survey Vector Map Local hosted on the Geograph website and which is entitled the Interactive Coverage Map became available online.  This mapping has many spot heights not on any other publicly available Ordnance Survey map and gives a 302m spot height on the area of this hill’s bwlch.  This spot height is also shown on Ordnance Survey data that appears on the Magic Maps website.

Extract from Ordnance Survey data hosted on the Magic Maps website

During the re-assessment of this hill’s details the summit height was amended to 334m based on the 1096ft (334.06m) imperial height that appears on the summit area of this hill on the series of Ordnance Survey Six-Inch maps.  These re-assessments resulted in the hill being listed with 32m of drop.

Extract from the series of Ordnance Survey Six-Inch maps

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. 

LIDAR summit image of Yr Allt

LIDAR bwlch image for Yr Allt

The confirmation of the reclassification of Yr Allt from Sub-Trichant status is due to LIDAR analysis, resulting in a 334.0m height to a remaining natural summit and a 301.7m bwlch height, with these values giving this hill 32.3m of drop which is sufficient for it to be classified as a Trichant.

The full details for the hill are:

Group:  Mynyddoedd Duon

Name:  Yr Allt

OS 1:50,000 map:  161

Summit Height:  334.0m (LIDAR, natural summit)

Summit Grid Reference:  SO 19677 35879 (LIDAR, natural summit)

Bwlch Height:  301.7m (LIDAR)

Bwlch Grid Reference:  SO 20120 35549 (LIDAR)

Drop:  32.3m (LIDAR)

Myrddyn Phillips (December 2019)

Mapping Mountains – Trimble Surveys – Moel y Gamelin

18.09.19  Cyrn y Brain (SJ 208 488, only bwlch surveyed)

And what a fun day today was.  This was the ninth and last roadside bwlch survey, and all had been researched either by LIDAR analysis initially conducted by Aled Williams, or looked at with 5m contouring on the OS Maps website and also compared against the digitised image from a Google car.  The latter was also used to find convenient parking places.  The main purpose, outside of bwlch surveying, was to get out and partake in a road trip whilst the weather remained dry and gloriously sunny.

Cyrn y Brain (SJ 208 488)

The last bwlch survey of the day is adjoined to Cyrn y Brain which rises in a great lump of heather on the eastern side of Bwlch Oernant; otherwise known as the Horseshoe Pass.  I’d surveyed this bwlch once before and also the summit on a separate outing, but as Aled’s LIDAR analysis indicated that my bwlch placement was an approximate ten metres from the critical point I wanted to re-visit and compare the first Trimble placement to where LIDAR gives the position of the bwlch.  From experience the latter will be the most accurate on this kind of terrain.

Having just surveyed the bwlch of Moel Fama which is situated in the valley to the north of Bwlch Oernant, it was only a short drive up the continuation of the A542 road to its high point were the delights of the Ponderosa Café beckoned.  Whenever I pass this place I am reminded of a meeting held in the Ponderosa with two ex-colleagues when one of them tried to ban me from all future Scottish surveys.  A surprising stance considering I had just given permission for them to use Trimble data in their database and to have nothing offered in return except for banishment was a surprise to say the least.   Even more surprising when one considers that I thought the person who was trying to ban me was a good friend.

The bwlch of Cyrn y Brain

I pulled in to the car park at the Ponderosa and found a quiet spot to leave my car, looked over at those unfortunate memories from five years ago, turned my back to the Café and walked toward a gate which gave access to the heather beyond.

The ten figure grid reference produced by Aled’s LIDAR analysis led me to the critical point of the bwlch.  This was beside a slither of water with heather and moor grass giving backdrop on to the rising mass of Cyrn y Brain.

It felt good to be here, even though those memories still make me shudder with the sheer gall of the man.  Once the allotted data were gathered and stored I closed the Trimble down, took a few photos with Cyrn y Brain as backdrop and walked the short distance back to my car. 

Gathering data at the bwlch of Cyrn y Brain

Nine roadside bwlch surveys for the day were now complete, with another six completed six days ago.  A good tally with some important results to look forward to, all that remained was the drive back home after another excellent day.

Survey Result:

Cyrn y Brain

Summit Height:  564.6m (converted to OSGM15, from previous Trimble GeoXH 6000 survey)

Summit Grid Reference:  SJ 20820 48875 (from previous Trimble GeoXH 6000 survey)

Bwlch Height:  400.7m (converted to OSGM15)

Bwlch Grid Reference:  SJ 19348 48168

Drop:  163.9m

Dominance:  29.02%

  

For details on the summit survey of Cyrn y Brain

For details on the 1st bwlch survey of Cyrn y Brain

For further details please consult the Trimble Survey Spreadsheet

Mapping Mountains – Significant Name Changes – Y Pedwarau – The 400m Hills of Wales

Y Glog (SO 222 690)

There has been a Significant Name Change to a hill that is listed in the Y Pedwarau – The 400m Hills of Wales, with the summit height, bwlch height and their locations, the drop and status of the hill derived from a survey with the Trimble GeoXH 6000 conducted by Myrddyn Phillips on the 8^th April 2016 and subsequently confirmed by LIDAR analysis conducted by Aled Williams.

The criteria for the list that this name change applies to are:

Y Pedwarau – The 400m Hills of Wales.  Welsh hills at or above 400m and below 500m in height that have 30m minimum drop, the list is co-authored by Myrddyn Phillips and Aled Williams and is published on Mapping Mountains in Google Doc format.

The hill is adjoined to the Elfael group of hills, which are situated in the eastern part of Mid and West Wales (Region B, Sub-Region B1), and it is positioned with the B4356 road to its north and the A488 road to its south and east, and has the village of Llangunllo towards the north north-west and the town of Trefyclo (Knighton) towards the east north-east.

The hill appeared in the original Welsh 400m P30 list published on Geoff Crowder’s v-g.me website under the name of Glog Hill, which is a prominent name that appears beside the summit of this hill on contemporary Ordnance Survey maps.  This is also the name the hill was listed by in the 1^st edition of the Y Pedwarau published by Europeaklist in May 2013.

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

When the original Welsh 400m P30 list was published on Geoff Crowder’s v-g.me website I paid little regard to the use of language, 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 are now considered inappropriate or where another name is viewed as being more appropriate.   

The intricacies of language and prioritising one in favour of another for listing a hill is fraught with complication, with originating Cymraeg names being anglicised and also originating English names being cymricised, examples such as these are more common in border country and especially so for anglicised forms.  There is no steadfast rule that fits all, but as a standard a name that has its origins in the Welsh language should be prioritised in favour of a contemporary anglicised or English version of the name, and ideally for this to be substantiated by either historic documentation and / or contemporary usage.  Likewise, if a name exists where an element of it is in English and if this name applies to a hill that is situated in a Welsh speaking part of Wales it is standard practice to use a full Welsh term for the name.  It is also standard practice to use a Welsh name for a hill if another name exists that has originated in a different language.

Extract from the Parochial Queries returned to Edward Lhwyd

Therefore, the name this hill is now listed by in the Y Pedwarau – The 400m Hills of Wales is Y Glog, with the Welsh originating name for this hill recorded as a mountain under the parish of Bledhvach by E. Lhwyd in 1696, and therefore prioritised over the part English version that appears on contemporary Ordnance Survey maps, which for listing purposes is standard practice.

The full details for the hill are:

Group:  Elfael

Name:  Y Glog

Previously Listed Name:  Glog Hill

OS 1:50,000 map:  137, 148

Summit Height:  406.8m (LIDAR)

Summit Grid Reference:  SO 22272 69087 (LIDAR)

Bwlch Height:  357.2m (converted to OSGM15)

Bwlch Grid Reference:  SO 20956 69962

Drop:  49.6m (LIDAR summit and Trimble bwlch)

Myrddyn Phillips and Aled Williams (December 2019)