Showing posts with label Mynydd Tŷ'r Sais. Show all posts
Showing posts with label Mynydd Tŷ'r Sais. Show all posts

Thursday, 29 July 2021

Mapping Mountains – Summit Relocations – Y Trichant – The 300m Hills of Wales


Mynydd Tŷ’r Sais (SH 855 004) 

There has been a Summit Relocation 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 a Trimble GeoXH 6000 survey, prompted by an enquiry from Ronnie Bowron based on detail in the summit analysis programme produced by Joe Nuttall. 

Mynydd Tŷ'r Sais (SH 855 004)

The criteria for the list this summit relocation affects 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. 

Y Trichant - The 300m Hills of Wales by Myrddyn Phillips

The name the hill is listed by is Mynydd Tŷ’r Sais and it is adjoined to the Pumlumon group of hills, which are situated in the north-western part of Mid and West Wales (Region B, Sub-Region B2), and it is positioned with the A470 road to its north, minor roads to its west and south, and the B4518 road to its east, and has the village of Llanbrynmair towards the north-east. 

When the original 300m height band of Welsh P30 hills was published on Geoff Crowder’s v-g.me website, this hill was not included in the Hills to be surveyed sub list, as it was considered not to meet the criteria then used for this sub category. 

After 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 26m of drop, based on the 359m summit spot height positioned at SH 85453 00439 that appears on the Ordnance Survey 1:50,000 Landranger and the 1:25,000 Explorer map and the 333m bwlch spot height that appeared on the Ordnance Survey Vector Map Local hosted on the Geograph website and which was entitled the Interactive Coverage Map. 

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

Since the original publication of the P30 lists of Geoff Crowder’s v-g.me website there have been a number of Ordnance Survey maps made available online, some of these are historic such as the series of Six-Inch maps on the National Library of Scotland website, whilst others are current and digitally updated such as the mapping on the OS Maps website and the WalkLakes website. 

One of the resources now available online is the mapping on the OS Maps website.  This is the replacement for OS Get-a-map and until recent times had contours at 5m intervals which were proving consistently more accurate compared to the 5m contours that sometimes appear on the Ordnance Survey 1:25,000 Explorer map and used to appear on the online Vector Map Local.  This mapping shows an uppermost 360m ring contour and bwlch contouring much nearer the 330m height when compared to the contouring on the Ordnance Survey 1:25,000 Explorer map. 

Another resource now available online is the mapping on the WalkLakes website which hosts an interactive 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 a 362m spot height is given on the area of its summit and again the bwlch contouring is much nearer the 330m height when compared to the contouring on the Ordnance Survey 1:25,000 Explorer map. 

Extract from the WalkLakes website

These details resulted in this hill being prioritised for a Trimble GeoXH 6000 survey.  This took place on the 30.03.21 resulting in a 362.2m summit height positioned at SH 85514 00483, and this comes within the parameters of the Summit Relocations used within this page heading, these parameters are: 

The term Summit Relocations applies when the hill’s high point is found to be positioned; in a different field, to a different feature such as in a conifer plantation, placed within a different map contour, to a different point where a number of potential summit positions are within close proximity, or when natural ground or 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, 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. 

The Trimble GeoXH 6000 gathering data at the summit of Mynydd Tŷ'r Sais

Therefore, the listed summit height of this hill is 362.2m and its new position is SH 85514 00483, this position is not given a spot height on contemporary Ordnance Survey maps, but does have a 362m spot height on the interactive mapping hosted on the WalkLakes website and is approximately 60 metres north-eastward from where the previously listed summit is positioned. 

 

The full details for the hill are:

Group:  Pumlumon

Name:  Mynydd Tŷ’r Sais 

OS 1:50,000 map:  135, 136

Summit Height:  362.2m (converted to OSGM15)                                                           

Summit Grid Reference (New Position):  SH 85514 00483 

Bwlch Height:  329.9m (converted to OSGM15) 

Bwlch Grid Reference:  SH 86220 00690 

Drop:  32.2m 

 

Myrddyn Phillips (July 2021)

  

Tuesday, 27 July 2021

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

 

Mynydd Tŷ’r Sais (SH 855 004) 

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 a Trimble GeoXH 6000 survey, prompted by an enquiry from Ronnie Bowron based on detail in the summit analysis programme produced by Joe Nuttall. 

Mynydd Tŷ'r Sais (SH 855 004)

The criteria for the list this height revision affects 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. 

Y Trichant - The 300m Hills of Wales by Myrddyn Phillips

The name the hill is listed by is Mynydd Tŷ’r Sais and it is adjoined to the Pumlumon group of hills, which are situated in the north-western part of Mid and West Wales (Region B, Sub-Region B2), and it is positioned with the A470 road to its north, minor roads to its west and south, and the B4518 road to its east, and has the village of Llanbrynmair towards the north-east. 

When the original 300m height band of Welsh P30 hills was published on Geoff Crowder’s v-g.me website, this hill was not included in the Hills to be surveyed sub list, as it was considered not to meet the criteria then used for this sub category. 

After 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 26m of drop, based on the 359m summit spot height that appears on the Ordnance Survey 1:50,000 Landranger and the 1:25,000 Explorer map and the 333m bwlch spot height that appeared on the Ordnance Survey Vector Map Local hosted on the Geograph website and which was entitled the Interactive Coverage Map. 

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

Since the original publication of the P30 lists of Geoff Crowder’s v-g.me website there have been a number of Ordnance Survey maps made available online, some of these are historic such as the series of Six-Inch maps on the National Library of Scotland website, whilst others are current and digitally updated such as the mapping on the OS Maps website and the WalkLakes website. 

One of the resources now available online is the mapping on the OS Maps website.  This is the replacement for OS Get-a-map and until recent times had contours at 5m intervals which were proving consistently more accurate compared to the 5m contours that sometimes appear on the Ordnance Survey 1:25,000 Explorer map and used to appear on the online Vector Map Local.  This mapping shows an uppermost 360m ring contour and bwlch contouring much nearer the 330m height when compared to the contouring on the Ordnance Survey 1:25,000 Explorer map. 

Another resource now available online is the mapping on the WalkLakes website which hosts an interactive 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 a 362m spot height is given on the area of its summit and again the bwlch contouring is much nearer the 330m height when compared to the contouring on the Ordnance Survey 1:25,000 Explorer map. 

Extract from the WalkLakes website

These details resulted in this hill being prioritised for a Trimble GeoXH 6000 survey.  This took place on the 30.03.21 resulting in a 362.2m summit height, and this 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. 

The Trimble GeoXH 6000 gathering data at the summit of Mynydd Tŷ'r Sais

Therefore, this hill’s new listed summit height is 362.2m and this was derived from a Trimble GeoXH 6000 survey, this is 3.2m higher than the previously listed summit height of 359m which appears as a spot height on the contemporary Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer map. 

 

The full details for the hill are: 

Group:  Pumlumon 

Name:  Mynydd Tŷ’r Sais 

OS 1:50,000 map:  135, 136

Summit Height (New Height):  362.2m (converted to OSGM15)                                                           

Summit Grid Reference:  SH 85514 00483 

Bwlch Height:  329.9m (converted to OSGM15) 

Bwlch Grid Reference:  SH 86220 00690 

Drop:  32.2m 

 

Myrddyn Phillips (July 2021)

 

 

 

Sunday, 25 July 2021

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


Mynydd Tŷ’r Sais (SH 855 004) – Sub-Trichant reclassified to Trichant 

There has been 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 a Trimble GeoXH 6000 survey, prompted by an enquiry from Ronnie Bowron based on detail in the summit analysis programme produced by Joe Nuttall. 

Mynydd Tŷ'r Sais (SH 855 004)

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. 

Y Trichant - The 300m Hills of Wales by Myrddyn Phillips

The name the hill is listed by is Mynydd Tŷ’r Sais and it is adjoined to the Pumlumon group of hills, which are situated in the north-western part of Mid and West Wales (Region B, Sub-Region B2), and it is positioned with the A470 road to its north, minor roads to its west and south, and the B4518 road to its east, and has the village of Llanbrynmair towards the north-east. 

When the original 300m height band of Welsh P30 hills was published on Geoff Crowder’s v-g.me website, this hill was not included in the Hills to be surveyed sub list, as it was considered not to meet the criteria then used for this sub category. 

After 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 26m of drop, based on the 359m summit spot height that appears on the Ordnance Survey 1:50,000 Landranger and the 1:25,000 Explorer map and the 333m bwlch spot height that appeared on the Ordnance Survey Vector Map Local hosted on the Geograph website and which was entitled the Interactive Coverage Map. 

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

Since the original publication of the P30 lists of Geoff Crowder’s v-g.me website there have been a number of Ordnance Survey maps made available online, some of these are historic such as the series of Six-Inch maps on the National Library of Scotland website, whilst others are current and digitally updated such as the mapping on the OS Maps website and the WalkLakes website. 

One of the resources now available online is the mapping on the OS Maps website.  This is the replacement for OS Get-a-map and until recent times had contours at 5m intervals which were proving consistently more accurate compared to the 5m contours that sometimes appear on the Ordnance Survey 1:25,000 Explorer map and used to appear on the online Vector Map Local.  This mapping shows an uppermost 360m ring contour and bwlch contouring much nearer the 330m height when compared to the contouring on the Ordnance Survey 1:25,000 Explorer map. 

Extract from the OS Maps website

Another resource now available online is the mapping on the WalkLakes website which hosts an interactive 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 a 362m spot height is given on the area of its summit and again the bwlch contouring is much nearer the 330m height when compared to the contouring on the Ordnance Survey 1:25,000 Explorer map. 

Extract from the WalkLakes website

These details resulted in this hill being prioritised for a Trimble GeoXH 6000 survey.  This took place on the 30.03.21 resulting in the hill being confirmed as having more than 30m of drop. 

The Trimble GeoXH 6000 gathering data at the summit of Mynydd Tŷ'r Sais

The Trimble GeoXH 6000 gathering data at the bwlch of Mynydd Tŷ'r Sais

Therefore, the reclassification of this hill from Sub-Trichant status is due to a Trimble GeoXH 6000 survey, resulting in a 362.2m summit height and a 329.9m bwlch height, with these values giving this hill 32.2m of drop, which is sufficient for it to be classified as a Trichant. 

 

The full details for the hill are: 

Group:  Pumlumon 

Name:  Mynydd Tŷ’r Sais 

OS 1:50,000 map:  135, 136

Summit Height:  362.2m (converted to OSGM15)                                                           

Summit Grid Reference:  SH 85514 00483 

Bwlch Height:  329.9m (converted to OSGM15) 

Bwlch Grid Reference:  SH 86220 00690 

Drop:  32.2m 

 

Myrddyn Phillips (July 2021)

 

 

 

 

 

  

Sunday, 23 May 2021

Mapping Mountains – Trimble Surveys – Pumlumon


30.03.21  Mynydd Tŷ’r Sais (SH 855 004), Briwnant (SH 847 017), Ffridd Pen y Graig (SH 842 018) and Pen yr Allt (SH 842 025) 

Ffridd Pen y Graig (SH 842 018)

The first true warmth of spring was savoured today, which for me is unusual as I am prone to suffer in the heat.  But winter can be oppressive with shortened day light hours and grey overbearing sky’s that during this year were only compounded by Covid restrictions, therefore the new growth and today’s warmth brought on by seasonal change highlighted a new beginning which conveniently matches many Covid restrictions recently being lifted. 

Today I wanted to visit four hills, with the first; Mynydd Tŷ’r Sais being a candidate for reclassification to P30 status.  These hills can be easily combined from the small community of Darowen and would for me, complete this block of land, as I had visited and surveyed adjacent hills to the west and also the east in recent years. 

I was parked and walking down a steep paved lane leading to Tan-llan by just past 8.30am.  I had a thin one skin jacket and gloves on as although the forecast of warn weather would quickly materialise the early morning still had a lingering chill. 

Chilled morning

Beyond Tan-llan the narrow paved lane deteriorated to a rough track, this fords a stream at its low point.  The adjacent fields were dew soaked with the sound of bleating lambs echoing through the morning mist.  The latter cloaked the hills but soon their tops emerged with just the last vestiges of mist clinging to their sides.  It was a beautiful morning to be out in this part of the world. 

Low mist still clung to the valley

I wanted to access Mynydd Tŷ’r Sais from the west; this involved the use of a private track.  Close to Rhos-Drynog farm I stood back as a number of sheep were being ushered from an adjacent field across the track to the opposing field.  The farmer who was on a quad bike pulled up and we chatted for a number of minutes.  He pointed out Maen Llwyd; an impressive standing stone that I had been close to lower on the track.  We conversed about the hills and he gave me names for a number of them.  He kindly let me continue up the track and I left after thanking him. 

Rheinallt Wigley

By now it was warming up and I had already dispensed with my thin gloves and soon afterward my jacket was packed away.  It would remain warm for the rest of the day, with later reports that Kew Gardens had recorded the warmest March day in Britain since 1968. 

The track leading to the first hill of the day

I followed the track ever upward to sheep pens and soon left it to strike up over grazing fields to a small conifer plantation, beyond which I followed the ridge fence heading up toward the top of the hill.  This hill is given a 359m spot height on contemporary Ordnance Survey 1:25,000 Explorer maps, but the summit analysis programme produced by Joe Nuttall and investigative work conducted by Ronnie Bowron indicated that its true summit is higher, and that in all likelihood its drop value exceeds 30m. 

The lower 359m spot heighted top is on the right and the higher 362.2m summit is on the left

I love surveying such hills and today the conditions were perfect with hardly a breath of breeze and with warmth this meant I could take my time and survey every point deemed necessary.  Surprisingly this consisted of only one on the summit area, with the highest point easily identified.  However its bwlch had a number of options for its critical point and I surveyed three in all, with each having undulations between.  This took just over an hour to complete, but will give confidence toward this hill’s drop value and therefore status. 

Gathering data at the summit of Mynydd Tŷ'r Sais with the lower 359m spot heighted top in the background

Leaving the bwlch I descended toward Lluest-cethingrych; an abandoned remnant when families and shepherds would use these hills from higher habitations.  The ruined house now looked down on a green track with its mature trees still shielding it from the worst of the weather.  Such places dot the upland landscape and all could tell a story of times long gone and forgotten. 

The old ruin of Lluest-cethingrych

The green track continued gravelled on the opposing banks of the Nant Tŷ’r Sais, this contoured around a hillside to the narrow paved lane east of Darowen.  On the way I stopped and smiled and took a few photos of an Argos container which shone bright sky blue in the morning’s sunshine.  It looked completely out of place amongst such beautiful and gentle countryside, but for me, it summed up one aspect why I love Wales so mush.  This country is not forensically presented where everything looks twee without a blade of grass out of place, it is lived in and all the better for such oddities. 

Looking completely out of place but still rather appealing

Ahead lay the connecting bwlch of Ffridd Pen y Graig, I’d investigated its surrounds via a Google car on my laptop and the point to survey looked as if it was submerged under a thin strip of trees that followed the valley bottom. 

Looking down on the bwlch of Ffridd Pen y Graig

I accessed the low field where the bwlch was placed via a gate and circumvented as much of the reed grass that grew near its flattest part as I could.  It was relatively easy to pinpoint the approximate position of the bwlch which was placed in a depression beside a fence and under a number of trees.  I imagined I’d be waiting for an age for the Trimble to attain the 0.1m accuracy level before data should be logged, but having set the equipment up I checked it after a couple of minutes and there was the magic number, I quickly pressed ‘Log’ and scampered away to sit on a mossed bow and waited for the allotted data to be gathered and stored. 

Gathering data at the bwlch of Ffridd Pen y Graig

After packing the Trimble away I clambered over the near fence and walked across a field before using another fence to get on to a track on the edge of forestry.  This gave me access to a steep field where the warmth battered me as I ever so slowly crept uphill, resting frequently, but height was gained and I eventually emerged beside a gate which gave access to the upper part of the hill. 

Mynydd Tŷ'r Sais (SH 855 004)

Gates and sheep paths led me up toward the summit of Briwnant; my second hill of the day.  I was glad to reach its high point.  The sky was blue and skylarks sang and the warmth gave an early summer feeling. 

Briwnant (SH 847 017)

I spent a number of minutes assessing the summit area of Briwnant and once I’d chosen the spot for Trimble placement the equipment was soon set up gathering data.  During data collection I sat and looked down on a herd of cows as they slowly wandered down the valley, conveniently away from where the next survey was going to take place. 

Gathering data at the summit of Briwnant

The next survey was at the connecting bwlch between Briwnant and Ffridd Pen y Graig and was positioned close to a fence.  I used one of the fence posts to give the Trimble a semblance of elevation and gathered the allotted data.  This process took an inordinate amount of time as I set the equipment up and closed it down on a number of occasions as the 0.1m accuracy level was not attained.  However, perseverance can be beneficial and having re-positioned it the magic number appeared and I sat below it as it quietly beeped away gathering its all-important data.  This at least gave me a well-earned rest and by the time I set off up the steepening field in front I felt almost brand new! 

Gathering data at the summit of Ffridd Pen y Graig

The summit of Ffridd Pen y Graig consists of three potential highest points.  I assessed these from a number of directions and having decided which I thought the highest set the Trimble up with its internal antenna aligned with the highest bit of mossed rock.  Before pressing ‘Log’ I stood and watched the whole upper part of the summit delicately move in motion with the breeze as it was covered in the most delightful spider webs and these ebbed in the breeze almost as if alive.  The little spiders also scampered across the yellowed outer shell of the Trimble as it gathered summit data. 

Gathering data at the bwlch of Pen yr Allt

I was nearing the end of the walk and just had one bwlch and summit to survey; this was for Pen yr Allt, a sub hill which connects to Ffridd Pen y Graig.  I spent a number of minutes assessing its connecting bwlch before choosing the spot for Trimble placement.  The summit of Pen yr Allt is covered by LIDAR, the only one to be so of the points I had surveyed during the day, because of this its position was easy to identify, but just to be on the safe side I took a second data set from a nearby small grassed hummock. 

The way back to Darowen

Once the Trimble had gathered its twelfth data set of the day I closed it down, packed it away and retraced by steps over the connecting bwlch to a public footpath and stiles as they strode out across late afternoon sun drenched fields toward the sleepy surrounds of Darowen.  It had been another good day on the hill.

 

Survey Result: 

 

Mynydd Tŷ’r Sais

Summit Height:  362.2m (converted to OSGM15) (significant height revision)

Summit Grid Reference:  SH 85514 00483 (summit relocation confirmed) 

Bwlch Height:  329.9m (converted to OSGM15)

Bwlch Grid Reference:  SH 86220 00690

Drop:  32.2m (Sub-Trichant reclassified to Trichant)

Dominance: 8.90%

 

 

Briwnant

Summit Height:  284.2m (converted to OSGM15)

Summit Grid Reference:  SH 84709 01728 

Bwlch Height:  248.7m (converted to OSGM15)

Bwlch Grid Reference:  SH 84556 01935

Drop:  35.5m

Dominance: 12.49%

 

 

Ffridd Pen y Graig

Summit Height:  296.8m (converted to OSGM15)

Summit Grid Reference:  SH 84242 01824 

Bwlch Height:  189.5m (converted to OSGM15)

Bwlch Grid Reference:  SH 85325 01537

Drop:  107.3m

Dominance: 36.15%

 

 

Pen yr Allt

Summit Height:  266.6m (converted to OSGM15)

Summit Grid Reference:  SH 84232 02576 

Bwlch Height:  241.9m (converted to OSGM15)

Bwlch Grid Reference:  SH 84202 02341

Drop:  24.7m (200m Sub-Twmpau addition)

Dominance: 9.26%

 

 

 

For further details please consult the Trimble Survey Spreadsheet