Showing posts with label Pt. 576.0m (SH 559 475). Show all posts
Showing posts with label Pt. 576.0m (SH 559 475). Show all posts

Sunday, 19 November 2023

Mapping Mountains – Trimble Surveys – Moel Hebog


07.10.23  Pt. 576.0m (SH 559 475) 

Pt. 576.0m (SH 559 475) (Photo: Aled Williams)

I am fortunate to be in a position that I can choose which day to head to the hills, and therefore rarely venture out when conditions are not favourable, especially when it is misty and raining.  However, with only three hills remaining to complete the listing of the Welsh Highlands – Uchafion Cymru, even unfavourable conditions can get the better of one’s mentality and drag you out to the hill.

By 7.00am I was parked on Aled’s drive in Porthmadog and transferring my gear in to his car.  Overhead the hills were blanketed in low cloud and mist, with flecks of wind-blown drizzle adding bleakness to the prospect of venturing out on any hill.  Twenty minutes later and we were at the end of Cwm Pennant having found a convenient parking place just off the minor road close to the last farm in the valley.

As I stood beside the car I was not enthusiastic to head up in to the murk and suggested we could go back to Aled’s for a cuppa and chat, all he had to do was smile and agree and the day on the hill would have been postponed.  But, having driven up the valley he was enthusiastic for us to continue, and after a bit of internal grumbling I agreed.

The hill we were heading for is positioned between Moel Hebog and Moel yr Ogof.  I had passed its summit on numerous occasions but until today never visited.  It is spectacularly positioned above a natural cleft in rock, and overlooks a large pool that constitutes the bwlch connecting with Moel yr Ogof and has excellent distant views up to its higher immediate neighbours and across to Yr Wyddfa.  Today I’m afraid none of this was on show.

Leaving the car we headed toward the first stile of the day and followed a path forever heading up toward Bwlch Meillionen.  We were soon in the murk, with the morning’s drizzle intermittent.  Usually keeping to a path is easy in the mist as there is little else to visually concentrate on, however Aled wanted to examine some of the rock outcrops higher up, therefore we kept the Afon Cwm-llefrith close at hand on our right and ventured away from what is a good quad bike track that we followed after the summit adventure on our descent back out of the gloom.

When high on the hill we spent about 30 minutes pottering around rocky ground investigating various outcrops before joining a sheep path that took us toward the bwlch on the Moel Hebog side of it.  It was now decidedly blowie with the wind picking up the higher we ventured.  Even though the visibility was limited it felt good to be back here after so many years, and even though we were only going to be on the section between the higher 2,000ft peaks for a short time and not visit their summits, it was still thrilling to be so high.  We now headed left and walked down to the bwlch and then steeply up toward the cleft in the rock that gives passage toward the summit of Moel yr Ogof. 

Heading up toward the cleft in the rock

At the top of the cleft we headed left, clambered over a stone wall and gained steepening runnels of grass interspersed amongst rock that took us up toward the summit of the one hill of the day.  I waited on grass as Aled headed over to the high point, hunkering down as he neared the summit as the wind was whipping across the hill.  When he arrived back at my position he advised me to be careful and suggested I leave my rucksack on the grass before heading up to stand on the summit.  Rather foolishly I did not adhere to his advice and headed up on the rock.

The next few minutes are a bit of a blur.  The rock was wet and very greasy.  I remember being ever so careful with each foot placement, making sure that each step was on relatively flat rock and wriggling my foot on it to make sure of a firm placement before transferring my weight and gaining further progress.  The summit of this hill comprises a small rocky ridge with a sheer drop on its northern side down in to the depths of the cleft of rock that we had just walked up.  Its opposing side comprised slanting rock forever falling away down on its southern side.  It reminded me of a small Knight’s Peak in the Cuillin on Skye.

I was now within about 2ft of its high point and about 4 inches below it and the next thing I can remember is seeing rock shooting past my eyes as I slithered down the southern side of the hill.  I have no memory of slipping, just a feeling of near rock and wanting to stop my fall.  I suspect in such circumstances survival instinct kicks in and I remember clinging on to rock with my right hand and trying to wedge me feet in to any flat ground below my body.  At the very moment I stopped, Aled had jumped from his position on the grass, grabbing me as he did so.

The next five minutes I stood on the grass recovering as Aled kindly put a plaster on my right little finger which was bloodied.  I had grazed and scraped my left lower leg and left buttock, bruised my right upper thigh and my back behind my right shoulder.  Thankfully I did not slither very far, as even on this southern side the continuation down the rock was not welcoming.  I didn’t talk for a number of minutes as I suspect the shock of the situation had kicked in.  After partly recovering I headed back up, this time keeping below the small ridge, touching its high point with my hand and then hooking my right leg up so my foot at least also touched the high point, and then slowly made my way down to re-join Aled who waited on the safety of the small patch of grass. 

At the summit, just after slipping down it! (Photo: Aled Williams)

I was still aware that I was not saying much as we clambered back over the wall.  I then headed down the steep ground and waited in the cleft between the rock walls out of the wind as Aled headed over to visit an adjoining sub.  By the time he arrived back at the cleft I was in chatty mode.  I had also had time to examine my various grazes and what no doubt will be impressive bruising in a day of two.  

As suspected, my right thigh came out in a good bruise a couple of days later 

Standing there on my own waiting for Aled also gave me time to ponder how fortunate I had been as I was standing on a narrow ridge of rock in wind, with underfoot conditions particularly slippery and the thought of what would have happened if I had fallen on the northern side of the ridge is not very comforting as I would have gone over a sheer drop down in to the cleft.  The thought of this kept me awake for the following night as I closed my eyes and had horrible images of dropping in to mist enshrouded oblivion.  Thankfully I survived to see another day, and my thanks to Aled for grabbing me just as I had halted and being attentive after the event. 

Out of the murk heading toward the relative safety of the valley below

The onward journey was not as exciting as the summit adventure, but was much safer as we followed the quad bike track down from the bwlch through a series of gates and over stiles.  The underfoot conditions were particularly wet, but the path gave passage toward the safely of the car in the valley below.  Third to last hill survived, just another two to go. 

 

Survey Result:

 

Pt. 576.0m                                

Summit Height:  576.0m (LIDAR)

Summit Grid Reference:  SH 55928 47521 (LIDAR)

Bwlch Height:  560.4m (LIDAR)

Bwlch Grid Reference:  SH 55885 47595 (LIDAR)

Drop:  15.6m (LIDAR) (Welsh Highland Sub addition) (Welsh Highland Sub reclassified to Welsh Highland P15)

Dominance:  2.70% (LIDAR)

 

 

For further details please consult the Trimble Survey Spreadsheet

  

Monday, 12 June 2023

Mapping Mountains – Hill Reclassifications – Welsh Highlands – Uchafion Cymru


Pt. 576.0m (SH 559 475) – Welsh Highland Sub reclassified to Welsh Highland P15 

There has been a reclassification to the listing of the Welsh Highlands – Uchafion Cymru, with the summit height, bwlch height and their locations, the drop and status of the hill derived from LIDAR analysis conducted by Aled Williams. 

LIDAR image of Pt. 576.0m (SH 559 475)

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

Welsh Highlands – Uchafion Cymru Welsh hills at or above 500m in height with 15m minimum drop, with an accompanying sub list entitled the Welsh Highland Subs, the criteria for which is all Welsh hills at or above 500m in height with 10m or more and below 15m of drop.  This list is authored by Myrddyn Phillips and Aled Williams with the Introduction to the list published on Mapping Mountains in November 2015 and the latest update relating to the list published on Mapping Mountains in January 2023.

Welsh Highlands - Uchafion Cymru by Myrddyn Phillips and Aled Williams

The hill is being listed by the point (Pt. 576.0m) notation, and it is adjoined to the Moel Hebog 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 B4418 road to its north, the A487 road to its west and the A4085 road to its north-east, and has the village of Beddgelert towards the east.

When the original list that later became known as the Welsh Highlands – Uchafion Cymru was first compiled, this hill was not included as a Welsh Highland Sub as with no separate uppermost ring contour on the contemporary Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer map there was no map evidence to suggest that any form of hill with qualifying prominence existed. 

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

Since the original compilation of this list there are now a number of interactive maps originated from Ordnance Survey data that are available online.  One of these is the mapping on the Magic Maps website, and this map gives this hill a summit spot height of 576m which is positioned at SH 55928 47522.

Another resource now available online is 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 it also shows the 576m summit spot height. 

Extract from the interactive mapping hosted on the WalkLakes website

The details for this hill were also re-examined against the Ordnance Survey non-contour Vector Map Local hosted on the Geograph website and which is entitled the Interactive Coverage Map.  This is another map that has many spot heights that do not appear on other publicly available Ordnance Survey maps and it also gives a 576m summit spot height.

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 had contours at 5m intervals which were 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.  This mapping has bwlch contouring between 560m – 565m, with interpolation giving an estimated c 562m bwlch height.

The above interactive mapping prompted the addition of this hill to Welsh Highland Sub status and it was listed with an estimated c 14m drop, based on the 576m summit spot height and an estimated c 562m bwlch height.

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 reclassification of this from Welsh Highland Sub status is due to LIDAR analysis, resulting in a 576.0m summit height and a 560.4m bwlch height, with these values giving this hill 15.6m of drop, which is sufficient for it to be classified as a Welsh Highland P15.

 

The full details for the hill are: 

Group:  Moel Hebog

Name:  Pt. 576.0m

OS 1:50,000 map:  115

Summit Height:  576.0m (LIDAR)

Summit Grid Reference:  SH 55928 47521 (LIDAR)

Bwlch Height:  560.4m (LIDAR)

Bwlch Grid Reference:  SH 55885 47595 (LIDAR)   

Drop:  15.6m (LIDAR) 

 

For the additions, deletions and reclassifications to the Welsh Highlands – Uchafion Cymru reported on Mapping Mountains please consult the following Change Registers:

 

Welsh Highland P15s

 

Welsh Highland Subs

 

Aled Williams and Myrddyn Phillips (June 2023)

  

Tuesday, 28 July 2020

Mapping Mountains – Hill Reclassifications – Welsh Highlands – Uchafion Cymru


DUE TO SUBSEQUENT LIDAR ANALYSIS THIS HILL HAS BEEN RECLASSIFIED FROM WELSH HIGHLAND SUB STATUS TO WELSH HIGHLAND P15 STATUS


Pt. 576m (SH 559 475) – 500m Sub-Uchaf addition

There has been an addition to the listing of The Welsh Highlands – Uchafion Cymru, with the summit height, bwlch height and their locations, the drop and status of the hill derived from detail on contemporary maps produced from Ordnance Survey data.

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

The Welsh Highlands – Uchafion Cymru This is the revised draft title for the Welsh 500m P15s list that takes in all hills in Wales at or above 500m in height with 15m minimum drop.  Accompanying the main list are three sub lists, these are; 500m Sub-Uchaf, 490m Sub-Uchaf and the Double Sub category, with this hill being added as a 500m Sub-Uchaf.  The criteria for which are all Welsh hills at or above 500m in height with 14m or more and below 15m of drop.  The list is co-authored by Myrddyn Phillips and Aled Williams with the Introduction to the list being published on Mapping Mountains in November 2015 and an update relating to the list appearing on Mapping Mountains on the 19th June 2019.

As the authors do not know an appropriate name for the hill either from historic research or from local enquiry it is being listed by the point (Pt. 576m) notation, and it is adjoined to the Moel Hebog 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 B4418 road to its north, the A487 road to its west and the A4085 road to its north-east, and has the village of Beddgelert towards the east.

This hill was not included as a P14 Sub in the original list of Welsh 500m P15s that later became known as Yr Uchafion and latterly as The Welsh Highlands – Uchafion Cymru, as with no separate uppermost ring contour there was no map evidence to suggest that any form of hill with qualifying prominence existed.

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

Since the original compilation of this list there are now a number of interactive maps originated from Ordnance Survey data that are available online.  One of these is the mapping on the Magic Maps website, and this map gives this hill a summit spot height of 576m which is positioned at SH 55928 47522.

Extract from the Magic Maps website

Another resource now available online is 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 it also shows the 576m summit spot height.

Extract from the WalkLakes website

The details for this hill were also re-examined against the Ordnance Survey non-contour Vector Map Local hosted on the Geograph website and which is entitled the Interactive Coverage Map.  This is another map that has many spot heights that do not appear on other publicly available Ordnance Survey maps and it also gives a 576m summit spot height.

Extract from the Ordnance Survey non-contour Vector Map Local hosted on the Geograph 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.  This mapping has bwlch contouring between 560m – 565m, with interpolation giving an estimated bwlch height of c 562m.

Extract from the OS Maps website

Therefore, the addition of this hill to 500m Sub-Uchaf status is due to detail on contemporary maps produced from Ordnance Survey data, resulting in a 576m summit height and an estimated c 562m bwlch height, with these values giving this hill c 14m of drop, which is sufficient for it to be classified as a 500m Sub-Uchaf.


The full details for the hill are:

Group:  Moel Hebog

Name:  Pt. 576m

OS 1:50,000 map:  115

Summit Height:  576m (spot height)

Summit Grid Reference:  SH 55928 47522 (spot height)

Bwlch Height:  c 562m (interpolation)

Bwlch Grid Reference:  SH 55895 47581 (interpolation)
   
Drop:  c 14m (spot height summit and interpolated bwlch) 


For the additions, deletions and reclassifications to The Welsh Highlands – Uchafion Cymru reported on Mapping Mountains please consult the following Change Registers:










Aled Williams and Myrddyn Phillips (July 2020)