Sunday 4 October 2020

Mapping Mountains – Trimble Surveys – Carnedd Wen


11.07.20  Crasty Frain (SO 109 983)  

With the 5-mile keep local restriction now lifted I thought I’d venture farther afield than the confines of my own town, and however beautiful my local walks had been, it felt the time was right to visit a hill and use the Trimble for the first time in many months.

Crasty Frain (SO 109 983)

I’d planned three small walks visiting a newly appointed P30, a potential new Pedwar and a summit of a hill that had been relocated during lock down, and when coupled with a socially distant visit to friends in Llanidloes, the day ahead seemed a good way to reacquaint myself with the hills.

The weather forecast was ideal and by 8.35am I was parked in a large passing place on a country lane above the small community of Tregynon.  It was only a short walk up the continuation of the lane to where a gate gives access to a field.  The sun glinted through mature trees heavy with summer growth, a contrast to my last summit survey earlier in the year where patches of snow were still on the hill and a cloud inversion bedded the valley below.

Vehicle tracks led across the field through long summer grass up toward a boundary fence, where according to LIDAR the high point of this particular hill was placed.  On the opposite side of the fence is a grazing field that today had no sheep in it.

The fence wasn’t barbed so it was easy to stretch over and inspect the lay of land on the opposite side.  Below was the wooded Coed y Brain, whilst to the north-east was the farm of Red House where a tractor and digger were busy at work at a near, small quarry.

I decided to take two data sets, one at the fence boundary and the other a few metres from it on what I deemed to be the highest natural ground, with the fence boundary slightly raised, which is proving the norm for such things.

Gathering data at the field boundary

As the Trimble slowly ebbed down to its 0.1m accuracy level before data should be logged, I stood in the early morning sunshine and looked across at the Berwyn and Aran.  This western view always entices as these hills are shown as elongated spines and living in this part of Wales it is a view I know well, and one that I have missed over the last four months.

The view of the Aran ridge

Once data were gathered and stored I positioned the Trimble atop my rucksack on what I judged to be the highest natural ground of the hill and again gathered the allotted five minutes of data.

Gathering data at what was deemed the natural high point of the hill

This hill is a recent addition to the ranks of P30s and its inclusion was instigated by the summit analysis programme Joe Nuttall worked on.  Its details were then analysed via LIDAR by Jim Bloomer and subsequently by me.

LIDAR image of Crasty Frain (SO 109 983)

LIDAR is proving an extraordinary tool to have at one’s disposal and has resulted in many reclassifications, all are just excuses though to venture onto new ground and investigate different hills.

After the second data set was gathered and stored I donned my face mask and headed down toward the two people operating the tractor and digger.  Unfortunately the local farmer was not one of them and I was told he wouldn’t be back under midday, and not surprisingly they did not know a name for the hill, although one of the fields was known as the Side Field, but without this being substantiated this hill will be listed under the Tithe name of Crasty Frain which is given to the field where the summit of the hill is situated.



Survey Result:


 
Summit Height:  256.3m (converted to OSGM15) (significant height revision)

Summit Grid Reference:  SO 10995 98318 (summit relocation confirmed)

Bwlch Height:  226.1m (LIDAR)

Bwlch Grid Reference:  SO 10787 98754 (LIDAR)

Drop:  30.2m (Trimble GeoXH 6000 summit and LIDAR bwlch) (200m Sub-Twmpau reclassified to 200m Twmpau)

Dominance:  11.79% (Trimble GeoXH 6000 summit and LIDAR bwlch)









No comments: