Thursday, 8 October 2015

Mapping Mountains – Trimble Surveys – Mynydd Preseli


12.09.15  Carn Siân (SN 127 321)  

Carn Siân (SN 127 321)

My first time to the hills of Mynydd Preseli for a number of years, my memories from previous visits were of open hills with relatively easy ascents and distant coastal views, and all under big skies. 

A busy couple of days were planned with a late afternoon visit to Ynys Aberteifi (Cardigan Island) and tomorrow’s trip to Ynysoedd y Moelrhoniaid (The Skerries) having been organised by Adrian Rayner.  As one island is almost the full western length of Wales from the other it would mean many car miles were to be covered and as with trips such as these, when travelling a relatively great distance, it’s always beneficial to try and visit a few other hills on the way.

During the night the rain battered the countryside which was in contrast to the last nine days of settled weather, and as I left my bungalow at 6.40am and drove west towards Aberystwyth the rain continued and hammered down as I made my way over Eisteddfa Gurig.  By the time I’d driven past Aberteifi (Cardigan) the first semblance of white cloud and blue sky had poked its way through the mass of overcast grey.

I parked on the south side of the Mynydd Preseli hills in a small parking spot adequate for two or three cars at SN 127 307.  My plan was to visit Carn Siân which is listed as a c 63m drop Pedwar with a map summit height of 402m.  Thankfully I’d brought my wellies as I suspected island trips way prove a wee bit wet and with heavy overnight rain the hills may be a wee bit soggy.

A green track heads northward from the parking place and gains steady height around the western bulk of Carn Siân, as I walked on it patched sunlight struck the eastern face of the higher Foel Cwmcerwyn with its greened slopes disguising its moorland appeal.

The green track soon petered out to a path which proved wet and boggy in places, but it enabled me to gain height relatively quickly and I was soon at the area of the bwlch which connects Carn Siân to Foel Cwmcerwyn.  The bwlch consisted of long moor grass interspersed with purple heather; within its realm were a number of soggy puddles and very soon also a rucksack which had a Trimble sitting on its top.

As the Trimble gathered data I watched another shower develop to the west and slowly push my way, and as the first rain drops fell I turned my back to the shower and waited for the allotted five minutes of data to be gathered.  By the time the Trimble had gathered the last of its 300 points the shower had passed and I soon packed the equipment away and headed up toward the summit.

Gathering data at the critical bwlch of Carn Siân with Foel Cwmcerwyn in the background

The Trimble set-up position at the bwlch with Carn Siân in the background

I followed the path on the hillside that aims toward the east and the 300m tops of Carn Menyn and Foel Drygarn, reaching its high point I marched over tussock grass toward the upright stones at the summit of Carn Siân, these are a good indicator where the highest ground is placed but as I contemplated trying to balance the Trimble on the highest part of the narrow rock of one of the upright stones, I gave them a wiggle and each moved, so I looked for the highest ground at their base.

Within a few minutes the Trimble was set up on my rucksack gathering another data set.  During this process I stood quite a distance away and watched a couple walking up from the east, although the weather looked as if it was slowly improving there were still masses of grey murk accumulating out to the west with their showers spraying down on the land.  The bulk of these were just south from where I stood, with intermittent blue patches appearing in the sky to the north.

Using my rucksack as an improvised tripod next to the upright rocks at the summit of Carn Siân

The view east from the summit of Carn Siân

The Trimble set-up position at the summit of Carn Siân

Once the Trimble was packed way I set off down the hill on a path that aimed the way I wanted to go, off to the west a rainbow cast its magic colours across the northern part of Foel Cwmcerwyn with its bow highlighting the continued grey, showery weather still lingering across the land.

Still bathed in grey - Foel Cwmcerwyn and its rainbow

The path shot me down to my car and soon I was driving back to the high point of the A4329 road for my next walk of the day.  On the way the murk descended and rain spat out from the sky.  I wondered how long it would last and had decided that the comforts of the car were too appealing to venture out into it.  However, as I pulled into the car park at the top of the road the last spots of rain withered away and the sky brightened, excellent stuff!


Survey Result:


Carn Siân

Summit Height:  401.5m (converted to OSGM15) (Pedwar status confirmed)

Summit Grid Reference:  SN 12774 32142

Bwlch Height:  340.0m (converted to OSGM15)

Bwlch Grid Reference:  SN 12140 32340

Drop:  61.5m

Dominance:  15.32%



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




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