Saturday, 28 December 2019

Mapping Mountains – Trimble Surveys – Moel y Gamelin


18.09.19  Cyrn y Brain (SJ 208 488), only bwlch surveyed

And what a fun day today was.  This was the ninth and last roadside bwlch survey, and all had been researched either by LIDAR analysis initially conducted by Aled Williams, or looked at with 5m contouring on the OS Maps website and also compared against the digitised image from a Google car.  The latter was also used to find convenient parking places.  The main purpose, outside of bwlch surveying, was to get out and partake in a road trip whilst the weather remained dry and gloriously sunny.

Cyrn y Brain (SJ 208 488)

The last bwlch survey of the day is adjoined to Cyrn y Brain which rises in a great lump of heather on the eastern side of Bwlch Oernant; otherwise known as the Horseshoe Pass.  I’d surveyed this bwlch once before and also the summit on a separate outing, but as Aled’s LIDAR analysis indicated that my bwlch placement was an approximate ten metres from the critical point I wanted to re-visit and compare the first Trimble placement to where LIDAR gives the position of the bwlch.  From experience the latter will be the most accurate on this kind of terrain.

Having just surveyed the bwlch of Moel Fama which is situated in the valley to the north of Bwlch Oernant, it was only a short drive up the continuation of the A542 road to its high point were the delights of the Ponderosa Café beckoned.  Whenever I pass this place I am reminded of a meeting held in the Ponderosa with two ex-colleagues when one of them tried to ban me from all future Scottish surveys.  A surprising stance considering I had just given permission for them to use Trimble data in their database and to have nothing offered in return except for banishment was a surprise to say the least.   Even more surprising when one considers that I thought the person who was trying to ban me was a good friend.

The bwlch of Cyrn y Brain

I pulled in to the car park at the Ponderosa and found a quiet spot to leave my car, looked over at those unfortunate memories from five years ago, turned my back to the Café and walked toward a gate which gave access to the heather beyond.

The ten figure grid reference produced by Aled’s LIDAR analysis led me to the critical point of the bwlch.  This was beside a slither of water with heather and moor grass giving backdrop on to the rising mass of Cyrn y Brain.

It felt good to be here, even though those memories still make me shudder with the sheer gall of the man.  Once the allotted data were gathered and stored I closed the Trimble down, took a few photos with Cyrn y Brain as backdrop and walked the short distance back to my car. 

Gathering data at the bwlch of Cyrn y Brain

Nine roadside bwlch surveys for the day were now complete, with another six completed six days ago.  A good tally with some important results to look forward to, all that remained was the drive back home after another excellent day.



Survey Result:


Cyrn y Brain

Summit Height:  564.6m (converted to OSGM15, from previous Trimble GeoXH 6000 survey)

Summit Grid Reference:  SJ 20820 48875

Bwlch Height:  400.7m (converted to OSGM15)

Bwlch Grid Reference:  SJ 19348 48168

Drop:  163.9m

Dominance:  29.02%

  














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