Mapping Mountains – Trimble Surveys – Stiperstones

29.08.20  Corndon (SO 305 969) and Lan Fawr (SO 297 967, previously Trimbled)  

Triangulation pillars have adorned the tops of our hills for many years.  They were used for triangulating heights, however with their function complete they are now redundant, as photogrammetry and the use of GNSS have superseded in taking further height values.

Corndon (SO 305 969)

Although their reason for being is now redundant, they act as beacons signifying the summit of many a hill, which can be a welcome sight after a prolonged ascent.  As they are now redundant some are showing the ravages of time after facing years of battering winds and freezing temperatures.  However, there are a select few who venture out to help maintain trig pillars, and today I was invited by Alex Cameron to join him, Adrian Dust and Tony Jenkins to re-paint the triangulation pillar on top of Corndon; one of my local hills.

We met just to the north-west of the summit where a track leaves the narrow road and heads up toward the bwlch between Corndon and Lan Fawr; one of the outlying P30s adjoined to this compact group of hills.

Knowing that Alex, Dusty and Tony would no doubt catch me up, I set off a few minutes ahead of them.  Leaving the track for open steep hillside I plodded up as the view to the west ever opened up, with Cadair Idris, the Aran and the Y Berwyn all lined up on the horizon.  Soon the intrepid painters caught me up and I followed behind them for the remaining distance to the summit.

The view to the west as I'm quickly caught up

Once at the top Alex cleaned the trig pillar with a wire brush and then set about the paint job.  Whilst the first coat was applied I set the Trimble up aligned with the high point of the hill, which is a small protruding rock a few metres from the base of a large cairn and also the trig pillar.

Starting the process of re-painting the trig pillar

I’d previously surveyed the summit of Corndon in March 2015, but the opportunity to do so again was not to be missed, especially as we would be on the summit for around an hour.  Therefore, the Trimble could be set-up gathering data for as long as we were there.  Such a length of time is a rarity for my surveys as usually five minutes of data is gathered.

The Trimble GeoXH 6000 gathering data during the first summit survey of Corndon

By now the trig was looking extremely smart in its new whiter coat of paint, with two sides of the four complete with their first coat.  During the painting and gathering data process a number of people from various directions approached the summit.  A few asked whether we were employed by Ordnance Survey, one enquired about the Trimble, but the majority hunkered down with their sandwiches out of the brisk northern wind which chilled proceedings.

Starting on the last two sides of the trig

The first coat now complete, the painters tidied up a number of patches and applied a second coat.  The trig was now looking decidedly white and sparkled when direct sunlight hit it.

The finished trig pillar with (L-R) Tony Jenkins, Adrian Dust and Alex Cameron

I closed the Trimble down having gathered over 64 minutes of data, and all that remained were the customary photos to be taken and a walk down the southern ridge, swinging westward following a fence line and path to the bwlch between Corndon and Lan Fawr.  The latter is listed as a Pedwar and as we were near it we visited its summit which gives good views back toward its higher neighbour.

Lan Fawr from Corndon

A saunter back on the track to the awaiting cars, and push bike in Alex’s case, and a good conversation about all things hilly when back at the cars rounded the day off very nicely.

Survey Result:

Corndon

  

Summit Height:  513.6m (converted to OSGM15, average of two Trimble GeoXH 6000 surveys)

Summit Grid Reference:  SO 30599 96922

Bwlch Height:  310.5m (converted to OSGM15, from previous Trimble GeoXH 6000 survey)

Bwlch Grid Reference:  SO 32519 99517 (from previous Trimble GeoXH 6000 survey)

Drop:  203.0m

Dominance:  39.54%

Lan Fawr  

Summit Height:  426.1m (converted to OSGM15, from previous Trimble GeoXH 6000 survey)

Summit Grid Reference:  SO 29711 96759 (from previous Trimble GeoXH 6000 survey)

Bwlch Height:  392.5m (converted to OSGM15, from previous Trimble GeoXH 6000 survey)

Bwlch Grid Reference:  SO 29968 96772 (from previous Trimble GeoXH 6000 survey)

Drop:  33.6m (from previous Trimble GeoXH 6000 survey)

Dominance:  7.88% (from previous Trimble GeoXH 6000 survey)

For details on the first Trimble GeoXH 6000 summit survey of Corndon and the Trimble GeoXH 6000 survey of Lan Fawr

For details on the Trimble GeoXH 6000 bwlch survey of Corndon

For further details please consult the Trimble Survey Spreadsheet