Monday, 19 March 2018

Mapping Mountains – Trimble Surveys – Beacon Hill

15.02.18  The Warren (SO 318 685)

The Warren (SO 318 685)

The Warren is listed as a 400m Sub-Four and straddles the border between England and Wales with its summit in England and its col in Wales.  I was running a tight schedule as I had already visited and surveyed the col of Worcestershire Beacon and the summit of Wapley Hill and wanted to de-twin the two 417m map heighted summits of Farrington Bank after this survey, and needed to get to Newtown for 6.00pm for a meal and the cinema, so although this hill can be combined in a more satisfying way with adjacent hills, I opted for a quick there and back from the convenience of the high narrow lane to the west of its summit.

As I left my car and straddled the wired fence giving access to the closely cropped grazing field where the summit of The Warren is situated, the wind whipped across the land with a chilled feeling, I hoped a quick walk to the hill’s high point would at least build a little inner warmth!

The summit was easy to identify and within a few minutes I’d set the Trimble up on the ground secured in place by three small flat rocks.  As it beeped away gathering the allotted five minutes of data I wandered down the upper part of the hill to take photos looking south toward Wapley Hill.

Gathering data at the summit of The Warren (SO 318 685)

Further north-east the sky was a sleet driven grey with huge shower clouds massing and depositing snow flurries on the higher ground, however The Warren remained bathed in sunshine, albeit very chilly.

To the north-west the observatory on top of one of the two 417m map heighted summits of Farrington Bank stood out against its near forestry and adjacent twin topped summit, these were my next surveying objective. 

Once the Trimble had collected its data I scampered back to my car and its relative warmth and drove toward the observatory, and after surveying the two 417m summits of Farrington Bank I drove the short distance back on the narrow lane to the area of the col of The Warren.

I’d recently looked at levelled heights on the series of Ordnance Survey Six-Inch maps on the area of this hill’s col whilst updating my part of the forthcoming The Fours publication, and had travelled the narrow road in a Google car and had also looked at the lay of land as I passed over the col whilst driving between The Warren and Farrington Bank, my conclusion was that the hill to hill traverse met at or close to the road junction beside a narrow conifer plantation.  However, to be sure I needed to investigate the lay of land on foot.

I parked at the start of a track leading to Upper Barn and walked the short distance back on the narrow lane to the area of the col, I looked at this col for a number of minutes following each hill to hill traverse to where they theoretically met, and then how this point developed in relation to the valley to valley traverse and concluded as I had before; the critical col is placed at the T-junction of narrow lanes.

As what I deemed to be the position of the critical col had mature conifer trees to its immediate south, and a telegraph pole, fence, gate and stunted trees beside it I retrieved my car and parked it on what I judged to be the col and aligned the Trimble with it whilst placed on the car roof, this gave it a 1.44m elevation above the col and a greater chance of picking up signals from orbiting satellites.  Thankfully the 0.1m accuracy level before data should be logged was quickly attained as a massive lump of grey murk was rolling down the valley slowly engulfing the town of Knighton, and I wanted to finish my day’s surveying in the dry.

The Trimble placed on top of my car's roof gathering data at the critical col of The Warren

Once five minutes of data were stored I closed the Trimble down, packed it away and drove back to the confines of the track leading to Upper Barn where I changed out of my hill gear, as I turned the key in the ignition the first drops of rain started to fall, and by the time I had driven down the narrow lane in to Knighton the streets were awash and the daylight had turned an exceedingly murky grey.  I arrived in Newtown at 6.00pm and made it to the pub to meet Eryl and John a couple of minutes later.

Survey Result:

Summit Height:  403.8m (converted to OSGM15)

Summit Grid Reference:  SO 31855 68590

Col Height:  376.4m (converted to OSGM15)

Col Grid Reference:  SO 31273 70279

Drop:  27.45m (400m Sub-Four status confirmed)

Dominance:  6.80%

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