Showing posts with label Barclodiau. Show all posts
Showing posts with label Barclodiau. Show all posts

Thursday, 23 May 2019

Mapping Mountains – Hill Reclassifications – 100m Twmpau


Barclodiau (SH 466 848) – 100m Sub-Twmpau reclassified to 100m Twmpau

There has been confirmation of a reclassification to a hill that is listed in the 100m Twmpau, with the summit height, bwlch height and their locations, the drop and status of the hill confirmed by LIDAR analysis and a subsequent summit survey with the Trimble GeoXH 6000, with both conducted by Myrddyn Phillips and the latter taking place on the 28th October 2018.

Barclodiau (SH 466 848)

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

100m Twmpau - Welsh hills at or above 100m and below 200m in height with 30m minimum drop, with an accompanying sub list entitled the 100m Sub-Twmpau with the criteria for this sub category being all Welsh hills at or above 100m and below 200m 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.

The name of the hill is Barclodiau, and it is adjoined to the Ynys Môn group of hills, which are situated in the north-western part of North Wales (Region A, Sub-Region A1), and it has the A5025 road to its north-east and the B5111 road to its west, and is positioned between the small communities of Llannerch-y-medd towards its west and Moelfre towards its east north-east.  

When the original 100m 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 did not meet the criteria then used in this 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 30m of drop, based on the 168m summit spot height that appears on the Ordnance Survey 1:25,000 Explorer map and an estimated bwlch height of c 138m based on interpolation of 5m contouring.

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

The drop value for this hill was re-assessed when the Ordnance Survey Vector Map Local hosted on the Geograph website became available online; this mapping is entitled the Interactive Coverage Map.  Although this mapping has the same 5m contour intervals as the 1:25,000 Explorer map its scale is greatly enlarged giving the opportunity for better interpolation.  This re-assessment resulted in the estimated c 30m drop value for this hill remaining the same.

Extract from the Ordnance Survey Vector Map Local hosted on the Geograph website

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.  

The confirmation of the reclassification of Barclodiau to 100m Twmpau status is due to LIDAR analysis, with a subsequent summit survey with the Trimble GeoXH 6000 resulting in a 168.6m Trimble summit height and a 137.1m LIDAR bwlch height, with these values giving this hill 31.5m of drop which is sufficient for it to be classified as a 100m Twmpau.

The Trimble GeoXH 6000 gathering data at the summit of Barclodiau


The full details for the hill are:

Group:  Ynys Môn

Name:  Barclodiau

OS 1:50,000 map:  114, 115

Summit Height:  168.6m (converted to OSGM15)

Summit Grid Reference:  SH 46674 84803

Bwlch Height:  137.1m (LIDAR)

Bwlch Grid Reference:  SH 46583 85001 (LIDAR)

Drop:  31.5m (Trimble summit and LIDAR bwlch)







Monday, 29 April 2019

Mapping Mountains – Trimble Surveys – Mynydd Twr


28.10.18  Yr Arwydd (SH 472 854), Pen y Castell (SH 468 853) and Barclodiau (SH 466 848)  

Yr Arwydd (SH 472 854)

I’d looked out on the hills comprising Mynydd Bodafon six days prior to today’s visit and had then hoped to reach them, but daylight hours, or lack of, dictated that I could not, and with their rock strewn profiles now edged in my memory I did not need a second chance to visit.  However, as I wanted to survey three summits and also then visit and survey Mynydd Eilian further to the north, I could not linger and although the afternoon and its sunshine was one to savour, a more investigative visit to these hills would have to wait for another day, as today it was going to be a quick up, down, up, down, up and down visit, but even with this mentality these hills did not disappoint.

Arriving beside Gors Fawr; the small lake at the base of these three hills, is like stepping back to a land stilled in time, where the ebb and flow of life is taken more leisurely, where the tranquil surrounds of water and hill also add and accentuate the beauty of such a place.

Gors Fawr

Sometimes when writing posts’ relating to my Trimble surveys it is hard to find new things to say, I also ask myself if this matters as I endeavour to treat each post as a separate entity, but still, on occasion one post does seem to merge in to another.  It is also hard to create quality when so many posts are written, I sometimes wish that I had more time to concentrate on these posts, to re-draft and edit, but time is a premium I seldom have, and therefore I suspect my writing on this occasion will not do the land of this place justice as the hills comprising Mynydd Bodafon and its surrounds are a thing of compact beauty.  If given the chance please visit, it is well worthwhile.

These three hills are rugged in nature with rock, heather and gorse dominating.  I knew paths existed but was unsure exactly where, but as most hills have paths on them, and as most of these paths aim toward the summit I did not have much concern about where to find them.

I set off having parked my car beside Gors Fawr and wandered up a track leading to one or two houses that dot the landscape hereabouts.  Leaving this track I followed a path heading north-east toward the base of the highest of these three hills; Yr Arwydd, which forms a part of the larger Mynydd Bodafon.

The path brought me to a small car park where a path carved its way upward through the vegetated hillside.  Although only a short ascent I thought I made good time and soon arrived at the summit, which is crowned with a trig pillar.  On my way toward the hill I’d seen a few small figures on its high point but no one was there when I arrived, which reassured me for the survey I was about to conduct, as having to ask someone if they would be good enough to stay away from the summit for however many minutes whilst the Trimble gathers its allotted data is not one of my favoured things to do.

The high point of this hill is beside the trig pillar and consists of rock, and it was relatively easy to judge which part of the rock was the highest.  Once the Trimble was wedged in place gathering its allotted data I sat a few metres below and away from it and savoured the warmth of autumn as the sun cast down.  Soon however I had to do what I do not like doing as within two minutes of activating the Trimble a walker appeared, I called over explaining what I was doing and asked if they would mind waiting about eight minutes until the survey and its ten minute allotted data set was complete.  Thankfully the walker had no problem with this and sat looking out at the view, and seemingly as I, more than happy to do so.

Gathering data at the summit of Yr Arwydd

Leaving the summit I chatted with the walker for a number of minutes, he was a botanist and told me about discovering a new fern that had not been documented in Britain before and pointed to where he had found it.  I explained about the Trimble and my hobby of surveying hills, we smiled at each other in a knowing way.  Eccentricity, obsession or just plain hobby, I do not care as I often marvel at what people do and their passion for things that others may think as unusual.

It was only a short walk down the path toward the small car park, on my way I looked out across to Pen y Castell; my next hill, and tried finding a path amongst its heathered slopes that would ease my upward progress.  I thought I’d spotted one, but when I walked up the continuation of the track from the car park and however much I peered at the heathered slopes no path materialised.  In such situations one has few options, and mine were limited to trying to find a path on the other side of the hill or going for it.  I knew even before I asked myself this question what I would do, and another minute later I wondered if I had chosen wisely as I was immersed in bracken and brambles with a steep bit of slope directly in front of me.  Thankfully what could have proven to be an awkward situated was soon overcome and I was over the worst of this part of the hill, and by keeping to the rock strewn slopes above passage upward was eased with only the occasional foray in to the heathery depths necessitated.

Pen y Castell from Yr Arwydd

Yr Arwydd from Pen y Castell

I was soon at the summit and had the Trimble aligned with its high point, it remained in its place for five minutes of data collection whilst I sat below it on a convenient rock eating a well-earned sandwich.

Gathering data at the summit of Pen y Castell

I thought of retracing my inward route, but it was a shorter distance to continue traversing the hill down to where a few houses lay below.  However, this downward route proved pathless, or at least was so on this particular day, I gathered momentum as gravity and a need to press on became my motivators and continued downward however prickly the copious amounts of gorse and bramble became, emerging beside a house whose owner was plastering its side, he looked up and asked if I had just come down from the hill, I turned and looked back up and said that it was a little rough, he said that not many people come down that way, saying there used to be a shepherds path on the hill, which is now overgrown.

I chatted with the man for a number of minutes and he kindly gave me a detailed route where the path lay for my next hill; Barclodiau.  Thanking him I pressed on down the track toward where my car was parked and onward directly opposite it to a narrow path amongst the heather, this I followed until it diverged, I followed it on the right as directed, and this led to Gors Arian, which today was slumbering in its marshy depths.  From here the path again diverged and as again directed I followed it left and this brought me straight up to the summit, this proved an easy way up what otherwise would have resulted in another rough ascent.

Tan Castell, Pen y Castell and Yr Arwydd from Barclodiau

The high point of Barclodiau consists of rock positioned a few metres from a small wind shelter, and as the Trimble gathered its allotted data I again stood and savoured the view, as I had done on countless hills over the last five years.  But views and hills are things never to tire of.

Gathering data at the summit of Barclodiau

Once the Trimble was safely packed away I scampered off down the path through the heather and emerged next to my car a few minutes later.  What a stunning small walk this proved to be, and these hills certainly did not disappoint.  Next stop Mynydd Eilian (SH 472 917).



Survey Result:



 
Summit Height:  177.5m (converted to OSGM15) (confirmed as higher than Mynydd Eilian [SH 47282 91719]

Summit Grid Reference:  SH 47242 85417

Bwlch Height:  N/A (sea)

Bwlch Grid Reference:  N/A (sea)

Drop:  177.5m

Dominance:  100.00%





Pen y Castell

Summit Height:  168.9m (converted to OSGM15, Trimble GeoXH 6000)

Summit Grid Reference:  SH 46823 85324 (Trimble GeoXH 6000)

Bwlch Height:  138.1m (LIDAR)

Bwlch Grid Reference:  SH 46971 85430 (LIDAR)

Drop:  30.9m (Trimble GeoXH 6000 summit and LIDAR bwlch)

Dominance:  18.28% (Trimble GeoXH 6000 summit and LIDAR bwlch)





Barclodiau

Summit Height:  168.6m (converted to OSGM15, Trimble GeoXH 6000)

Summit Grid Reference:  SH 46674 84803 (Trimble GeoXH 6000)

Bwlch Height:  137.1m (LIDAR)

Bwlch Grid Reference:  SH 46583 85001 (LIDAR)

Drop:  31.5m (Trimble GeoXH 6000 summit and LIDAR bwlch) (100m Sub-Twmpau reclassified to 100m Twmpau)

Dominance:  18.67% (Trimble GeoXH 6000 summit and LIDAR bwlch)