Wednesday, 6 May 2015

Mapping Mountains – Trimble Surveys – Fforest Glud

04.05.15  Newchurch Hill (SO 197 506) and Pt. 424.0m (SO 190 511) 

Pt. 424.0m (SO 190 511)
Having spent six hours visiting the hills around Red Hill and surveying fourteen points, I drove down the narrow lane toward the B4594 and headed steeply up another narrow lane as it dramatically gained height through the small community of Bryngwyn.  My destination was a grass verge beside this high road which I’d scouted in a Google car the previous evening, once parked I only had around 55m of ascent to the summit of Newchurch Hill.

Newchurch Hill and its three tops were brought to my attention by Alex when we had celebrated Carole Engel’s Pedwar completion last weekend.  Alex told me that the easterly top has a trig pillar on it and is given the map height of 424m, whilst the centrally positioned top is the listed Pedwar at a map height of 425m, and its westerly top is listed as a 21m drop 400m Sub-Pedwar with a map height of 424m.  Alex hoped that the westerly top would prove higher as he considered it the best of the three.

Leaving the car I joined another broad green path as it gained height and crested the ridge between these summits, a short walk east took me past the central top, and a few minutes later and I was beside the trig pillar on the easterly top.

The 400m Sub-Pedwar from the approach to its connecting ridge with Newchurch Hill
I crouched on my knees to judge where the highest ground lay, once a spot was chosen the Trimble was set down and started its data collection.  Farther to the east the elongated ridge of the Malvern Hills was easily picked out with the distinctive shape of Hanter Hill and its adjacent Hergest Ridge popping up over a ridge of farm landed green.

The Malvern Hills
Hanter Hill and Hergest Ridge
As the Trimble gathered its data I aligned the top of the trig with the two remaining summits, both seemed close in height.  Although not a scientific exercise it added impetus to the walk as the sky was progressively darkening from the south-west.

Gathering data at the westerly top of Newchurch Hill
Once the last of the 300 individual data points were collected I packed the Trimble away and scampered back to the central summit and placed the Trimble down on what I judged to be the high point.  This was on grass and moss, beside bracken.

Gathering data at the summit of Newchurch Hill
The next point to be surveyed was the bwlch connecting the central summit to the westerly one, this is given a spot height of 403m on the Ordnance Survey enlarged map on the Geograph website.  I spent a number of minutes assessing the lay of land from a number of directions and once the spot was chosen and data gathered I quickly walked up to the summit of the listed Sub-Pedwar.

As the Trimble gathered data I photographed it on the summit against the high peaks of Bannau Brycheiniog to the south and against the first hill that I visited earlier in the day, Bryn Gwyn.

Gathering data at the summit of the 400m Sub-Pedwar with the high peaks of Bannau Brycheiniog in the background
Once the Trimble was packed away I joined another lovely wide green path that led directly back to my car.  However, being a pedant I wanted to complete the days set of each respective summit and bwlch being surveyed and the bwlch for Newchurch Hill remained.  Therefore once back at the car I drove the short distance down toward the bwlch, parked on the open ground beside the narrow hill road and walked down into the confines of the bwlch.

The bwlch for Newchurch Hill has a steep gradient on its hills to hill traverse and is therefore enclosed by inclined hillsides, with trees also obstructing potential satellite coverage.  To add fun to proceedings the valley to valley traverse looked almost flat and was made of a bog.  However, the fun didn’t end here as map study indicated that the critical bwlch lay just to the south of an intervening fence, whilst the on site visit showed that the critical bwlch probably was placed just to the north of this fence.  This proved fun to clamber over as I can usually stretch over barbed wire fences, but this one had a greater drop on the farthest side and it was also a bit wobbly when tested with my weight!

Once safely standing in the bog I placed the Trimble down on grass and waited for it to obtain its 0.1m accuracy before data can be logged.  Considering the confined space it was trying to operate in this accuracy was obtained quickly.  I then clambered back over the fence and took a data set from the northern side.  As the Trimble did its stuff I sat on an old mossed tree trunk and wondered about the eccentric joys of surveying.

Gathering data at the first surveyed position for the bwlch of Newchurch Hill
Gathering data at the second surveyed position for the bwlch of Newchurch Hill
This last survey was the twentieth of the day and happy in the knowledge that every summit and bylchau with every alternative position having been surveyed I walked back to the car, changed into fresh clothes, ate a chocolate bar and luxuriated in the knowledge that I had missed the rain by only minutes, as by the time I was driving north toward Knighton the first raindrops fell.

Survey Result:

Newchurch Hill

Summit Height:  425.4m (converted to OSGM15)

Summit Grid Reference:  SO 19757 50603

Bwlch Height:  357.1m (converted to OSGM15)

Bwlch Grid Reference:  SO 18782 50257

Drop:  68.3m

Dominance:  16.06%


Summit Height:  424.0m (converted to OSGM15)

Summit Grid Reference:  SO 19035 51118

Bwlch Height:  403.5m (converted to OSGM15)

Bwlch Grid Reference:  SO 19211 50930

Drop:  20.5m (400m Sub-Pedwar status confirmed)

Dominance:  4.84%

For further details please consult the Trimble survey spreadsheet click {here}

No comments: