Showing posts with label Moel Heulog. Show all posts
Showing posts with label Moel Heulog. Show all posts

Sunday, 10 April 2022

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


Moel Heulog (SH 987 353) – 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 a Trimble GeoXH 6000 survey conducted by Myrddyn Phillips. 

Moel Heulog (SH 987 353)

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, and the Introduction to the Mapping Mountains publication of the list appearing on the 1st January 2022. 

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

The name the hill is listed by is Moel Heulog and it is adjoined to the Foel Cedig group of hills, which are situated in the southern part of North Wales (Region A, Sub-Region A3), and it is positioned with the B4402 road to its north-west, the B4391 road to its south and a minor road to its east, and has the town of Y Bala towards the 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, as it was considered not to meet the criteria then used for the main P30 category. 

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 29m of drop, based on the 376m summit spot height that appears on the Ordnance Survey 1:25,000 Explorer map and an estimated c 347m bwlch height, based on interpolation of 10m contouring between 340m – 350m. 

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

Since the original publication of the Welsh P30 lists on Geoff Crowder’s v-g.me website there have been a number of 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 were digitally updated such as the Ordnance Survey Vector Map Local that was hosted on the Geograph website and which was entitled the Interactive Coverage Map, whilst others are current and digitally updated such as the interactive mapping on the Magic Maps and WalkLakes websites. 

The details for this hill were re-assessed when the Ordnance Survey Vector Map Local hosted on the Geograph website and which was entitled the Interactive Coverage Map became available online.  This mapping had many spot heights not on other publicly available Ordnance Survey maps and for this hill it had a 346m bwlch spot height and when coupled with the 376m summit spot height, these values gave this hill 30m of drop. 

Gathering data at the bwlch of Moel Heulog

Gathering data at the summit of Moel Heulog

Therefore, the confirmation of the reclassification of this hill from Sub-Trichant status is due to a Trimble GeoXH 6000 survey, resulting in a 377.8m summit height and a 347.0m bwlch height, with these values giving this hill 30.7m of drop, which is sufficient for it to be classified as a Trichant. 

 

The full details for the hill are: 

Group:  Foel Cedig 

Name:  Moel Heulog 

OS 1:50,000 map:  125

Summit Height:  377.8m (converted to OSGM15, Trimble GeoXH 6000)

Summit Grid Reference:  SH 98750 35398 (Trimble GeoXH 6000) 

Bwlch Height:  347.0m (converted to OSGM15, Trimble GeoXH 6000) 

Bwlch Grid Reference:  SH 98941 35209 (Trimble GeoXH 6000) 

Drop:  30.7m (Trimble GeoXH 6000) 

 

Myrddyn Phillips (April 2022)




 

 

 

  

Thursday, 7 April 2022

Mapping Mountains – Trimble Surveys – Foel Cedig

 

25.02.22  Moel Heulog (SH 987 353) 

Moel Heulog (SH 987 353)

With the late winter storms receding and a forecast for a dry and partly sunny day, I took the opportunity and visited Moel Heulog, which is an unassuming hill rising beside the B4391 road as it crosses the Y Berwyn from Llangynog to Y Bala.  This hill is one of three potential P30s that I had noted during recent map study and LIDAR analysis and over the next few months I hoped to survey each in turn. 

Moel Heulog is given a 376m summit spot height on the contemporary Ordnance Survey 1:25,000 Explorer map; with interpolation of bwlch contouring giving this hill an estimated c 28m of drop.  However, the old Interactive Coverage Map that was hosted on the Geograph website had a 346m bwlch spot height positioned at SH 98935 35205, resulting in 30m of drop.  Therefore, this hill was reclassified to Trichant status due to the bwlch spot height, but with contouring suggesting otherwise it was prioritised for a Trimble GeoXH 6000 survey. 

Getting to the hill proved problematic as the upper part of the B4391 road was closed due to resurfacing.  This meant a long detour via Llanwddyn, Llyn Efyrnwy and the Hirnant pass before re-connecting with the B4391 road and then heading back up the Y Berwyn but this time in the opposite direction to the one planned.  Even this was a risk as I did not know how much of the upper section of the road was closed.  Thankfully Moel Heulog is positioned on the western end of this mountain road and it was the easterly section undergoing resurfacing.  After finding my designated parking spot I gathered all necessary equipment and headed over a small foot stile on to a soggy field which gave access toward the bwlch and then summit of this hill. 

A public footpath crossed the field heading toward a gate which gives access to the narrow lane on the eastern side of the hill; this lane also crosses the connecting bwlch.  All was relatively quiet as I made my way over the field, with an occasional rogue car still heading over the Y Berwyn on the closed road and a tractor slowly chugging its way on the narrow lane.  A drainage channel across the field meant that wellies; my preferred footwear for this time of year, proved a good chose with water flowing down the channel and muddied and slippery sides.  Beyond the drainage channel the field led up to the gate and lane at the bwlch. 

Having spent a few minutes assessing the lay of land beside the lane I positioned my rucksack and the Trimble atop it where I judged the critical point of the bwlch to be positioned.  I then measured the offset between the equipment’s internal antenna and the ground at its base and waited for the 0.1m accuracy level to be attained before data should be logged.  During the waiting process two cars approached from the north, I flagged each down in turn and explained what I was doing and asked them to be careful when driving past the equipment, they duly were and soon the Trimble was activated to gather its allocated data. 

Gathering data at the bwlch of Moel Heulog with the southerly top in the background

Having collected five minutes of bwlch data I approached the Trimble to close it down just as a tractor rounded the corner from the south.  It stopped and I chatted with the farmer for a few minutes before waving him off and packing the equipment away. 

This was my first survey for quite a while and it felt good to be back on the hill, albeit I had so far only been waiting on a country lane whilst the Trimble did its stuff.  However, many similar surveys have taken place over the last eight years and the waiting process has an unusual therapeutic element to it, and one that I am now accustomed to. 

The Trimble GeoXH 6000 set-up position at the bwlch of Moel Heulog

The map shows this hill with two tops, one metre apart in height, with the southerly the lower with a spot height of 375m.  It was this southerly top that I approached first and as I was now standing on its high point I decided to gather data from it.  As the Trimble quietly beeped away gathering its individual datum points I looked west toward the impressive bulk of Arenig Fawr standing out whitened with snow, with Mynydd Nodol to its right looking relatively small in comparison, it was this latter hill that was next on the day’s surveying agenda. 

The southerly top from the approach across the field

Arenig Fawr from the southerly summit of Moel Heulog

After packing the equipment away I headed over an intervening fence to the higher northerly summit where I was met by two friendly horses, both nuzzled toward me as I set the Trimble up.  One remained beside me as I measured the offset; they only sauntered off as I checked on the positioning of the equipment before activating it to gather data.  During data collection the horses thankfully kept their distance. 



An extremely friendly horse

It felt good to be on the summit, with horses and sheep as companions, blue sky and a slight chilled breeze as accompaniment, and waiting for the world to pass me by.  Such times are now the expected norm, and the experience seldom disappoints.  They afford a time to ponder, with thoughts aplenty or to drift where one’s mind wanders. 

Gathering data at the summit of Moel Heulog

As I left the summit using two gates for access down to the field and drainage channel below, I looked across to where the two horses now were, bade my farewells and wandered back toward my awaiting car.  The survey had been salvaged with the re-routing due to the road closure giving the prospect of not being able to get to the hill.  The survey also gave opportunity to get my mind-set back on hills and surveying after a long self-imposed winter break.  It felt good to be back. 

 

Survey Result:

 

Moel Heulog

Summit Height:  377.8m (converted to OSGM15)

Summit Grid Reference:  SH 98750 35398

Bwlch Height:  347.0m (converted to OSGM15)

Bwlch Grid Reference:  SH 98941 35209

Drop:  30.7m (Sub-Trichant reclassified to Trichant)

Dominance:  8.14%

 

 

For further details please consult the Trimble Survey Spreadsheet