Mapping Mountains – Trimble Surveys – Elenydd

 

29.09.20  Banc (SN 674 702) and Banc y Maen Rochorlem (SN 675 691) 

Banc y Maen Rochorlem (SN 675 691)

These two hills comprised the fifth and last walk of the day and prior to visiting I had conducted LIDAR analysis and come prepared with a series of ten figure grid references for each summit and bwlch.  However, it was only the summits I planned on surveying and each according to LIDAR and online logs of previous ascents had raised field boundaries at their high point, and as these are considered recent man-made constructs I needed to assess the lay of land and find the highest natural part of each summit before taking Trimble data. 

LIDAR summit image of Banc

By the time I arrived at my designated parking place beside a small Chapel, the intermittent sunshine from the morning had given way to grey skies and I wondered if rain would overtake me. 

The narrow paved lane continued beyond the Chapel and ends at the farm of Penlan, from here a track continued in the same direction toward the farm of Tynbwlch.  Compared to my peer group my pace amongst the hills was never the fasting, but I had my moments, nowadays I’ve succumbed to age and would describe myself a steady plodder, but I didn’t want to get wet and with friends to visit in Llanidloes before darkness overtook me I could not linger, so I steadily plodded as fast as I could! 

Walking along the track toward the first hill a quad bike appeared from an adjacent field and I flagged it down.  I introduced myself to Joseph Cook and explained my interest in his hill and its name.  Joseph told me that they know it as Banc, and happy with another name documented I thanked him, asked permission to visit the summit, which was duly granted with Joseph kindly directing me toward where gates were positioned on the hill. 

Joseph Cook of Tynbwlch

It didn’t take long to reach the summit of Banc, and I soon zeroed in to the high point indicated by LIDAR analysis.  The natural summit was at the base of a raised embankment which constitutes a field boundary and is positioned in a different field to where the high point of the embankment is placed, both were Trimbled. 

Gathering data at the natural high point of Banc

Gathering data at the high point of the raised field embankment

After the second data set was gathered and stored I contemplated what route to take for my descent, as between this hill and my next was an expansive and rather unsavoury looking bog.  I considered heading south-west from the summit toward a lane to bi-pass it, but decided to go for it and hope that I didn’t get stuck in its quagmired realm. 

I descended to Ty’n-llain and continued down a field to the mass of reed grass that constitutes the bog.  The boggiest parts could easily be distinguished as the reed grass was a subtler shade compared to the dryer parts.  I headed straight in to the bog.  I soon backtracked once water was encountered.  Now here I didn’t want to detour around the bog, so headed for an old fence where the semblance of a green strip of land poked through the reed grass.  Once on it, it led me down to another fence and the main part of the bog, so far so good.  The second fence was positioned close to a watery drainage ditch; I was soon over this and found a sheep path of sorts which led through the remainder of the bog.  I arrived on dry land amazed how quickly and relatively easily I’d gotten over and through what looked horrendous underfoot conditions. 

A gate then gave access in to a field where a herd of cattle were grazing; I quietly made my way around its periphery aiming for another gate which gave access to the field and the summit area of the hill.  As I slowly plodded up these fields a few breeze blown drops of rain fell, I thought the next hour would herald more of the same, but thankfully any grey murk quickly passed, leaving the remainder of the walk bathed in early evening light. 

The summit of this last hill of the day is positioned on the western side of the ridge embankment that crosses this hill from a north to south direction.  I soon had the Trimble set up and gathering its allotted data.  Happy that the highest natural part of the hill had been surveyed I decided against taking a data set from the highest part of the embankment. 

Gathering data at the natural high point of Banc y Maen Rochorlem

All that remained was the walk back to my car.  I checked the map and opted for a route across a couple of fields to connect with the track that then heads down to Pentre-gwnnws farm. 

Late afternoon light on the summit of Banc y Maen Rochorlem

Leaving the summit the light was aglow with a lowering sun giving beautiful colour.  I backtracked to the summit embankment to take a number of photos before following my lengthening shadow down the field to a gate and onward to the track and eventually the Chapel. 

Lengthening shadows pointing the way down the hill

The walk had taken 2 hours 20 minutes and another name had been documented with the Tithe supplying the field name for where the summit of the second hill is situated.  In all I’d visited five hills during the day, met a number of farmers, surveyed each summit and importantly surveyed the bwlch of Hafod Ithel; the latter was something that I’d wanted to do ever since getting the Trimble GeoXH 6000. 

All that remained was the drive to Llanidloes to visit Eryl and Rita for a socially distanced sit outside as dusk descended whilst listening to owls and enjoying a good mug of tea and biscuits; a great way to end the day. 

 

Survey Result:

 

Banc (significant name change)  

Summit Height:  289.4m (converted to OSGM15, Trimble GeoXH 6000)

Summit Grid Reference:  SN 67427 70214 (Trimble GeoXH 6000) (summit relocation confirmed)

Bwlch Height:  234.4m (LIDAR)

Bwlch Grid Reference:  SN 67366 69677 (LIDAR)

Drop:  55.1m (Trimble GeoXH 6000 summit and LIDAR bwlch)

Dominance:  19.02% (Trimble GeoXH 6000 summit and LIDAR bwlch)

 

 

Banc y Maen Rochorlem (significant name change)  

Summit Height:  299.3m (converted to OSGM15, Trimble GeoXH 6000) (significant height revision)

Summit Grid Reference:  SN 67513 69184 (Trimble GeoXH 6000) (summit relocation confirmed)

Bwlch Height:  206.2m (LIDAR)

Bwlch Grid Reference:  SN 69578 68344 (LIDAR)

Drop:  93.1m (Trimble GeoXH 6000 summit and LIDAR bwlch) (200m Sub-Twmpau reclassified to 200m Twmpau)

Dominance:  31.10% (Trimble GeoXH 6000 summit and LIDAR bwlch)

 

For details on the 2^nd visit to Banc y Maen Rochorlem

 

For further details please consult the Trimble Survey Spreadsheet