Mapping Mountains – Trimble Surveys – Y Berwyn

13.12.14  Ffridd (SJ 084 141), Allt Dolanog (SJ 067 134) and Pen y Berth (SJ 081 127, only bwlch surveyed)   

Allt Dolanog (SJ 067 134)

As I walked up the track from Dolanog the early morning chill mist rose with a silver sheen accentuating the overnight frost.  Overhead was blue sky and with a forecast of dry sunny conditions the day was set fair.

The silver sheen of winter

There were two hills I wanted to visit today and when combined the map indicated a good small circuit.  Dolanog consists of a few houses and is placed in the heart of northern mid-Wales with the Afon Efyrnwy (River Vyrnwy) running wild on the hamlet’s southern outskirts.

The track leading out of Dolanog skirted the south-eastern slopes of Allt Dolanog, which was to be my second and last hill of the day.  Although the overnight chill had left clear skies and morning frost, the accumulated rain over several days meant that the track was puddle ridden in places.  I’d come well prepared wearing winter wellies instead of walking boots.

There is a beauty in winter walking, a sense that the world is in hibernation with warmth emanating from hillsides of sunshine and yet because of the sun’s low angle much of the countryside can remain in its chill refinement, this was echoed in a delicate formation of frost crystals on leaves and bracken and yet within a matter of a few metres I walked into sunshine and the bright late year ebb of life in ragwort that was still clinging to its slender thread of life.

Frost on leaf

Sunshine on ragwort

The first hill I wanted to visit is named Ffridd on the Tithe map, having been first listed under the name of Penygorddyn which appears near to its summit but which is applicable to an ancient settlement lower on the hill and now covered in conifer plantation.  As the track contoured around the eastern slopes of Allt Dolanog it continued toward the first hill which is given the height of 296m on the Ordnance Survey map.  This hill lay ahead with its summit covered in sunshine and warmth whilst the track was still frost covered.

The track leading up to Ffridd, which is in the centre background

Soon the track diverged and I headed on its upward path into the conifer plantation, the going was relatively easy except for one part where fallen trees and overgrown undergrowth slowed progress, but once over and through the obstacle the track crept upward into the sunshine and the edge of the trees, beyond was the welcome site of open hillside.

First glimpse of open hillside through the conifers

Once over a fence I walked up to the high point and was confronted by a number of sheep, all in unison confidently marching toward me, once they realised I wasn’t the local farmer and had no feed for them they politely kept their distance.  The high point of the hill is crowned by rock and as I set the Trimble up to gather its customary five minutes of data I stood back and admired the high Aran which were covered in snow and cast a winter outlook out to the west, especially so when framed against the manicured green fields to their east.

Perched on the high point of Ffridd

It's always fun trying to balance and align the Trimble with the highest point of a rocky summit

The data produced by the Trimble will be interesting for this hill as I’d previously given it an estimated 32m of drop based on its 296m summit height and an estimated bwlch height of 264m.  This had been revised in recent years when the Ordnance Survey enlarged mapping on the Geograph website became available as this mapping has a 268m spot height on the area of the bwlch, giving the hill only 28m of drop.

After packing the Trimble away I set off northward toward the bwlch over and around intermittent bumps and then down a narrow lane.  The critical bwlch lay just off the lane in a closely cropped grassy field where its valley to valley traverse spread out in a seemingly never ending lushness of flatness.  I took two data sets and hoped that the hill would attain a minimum of 30m of drop as it would be a fine addition to the Twmpau.

Gathering data at the bwlch area of Ffridd

My planned route crossed a stream named Nant Dolwar that was no more than a slender blue slither on the map, as the fields led down steeply to the stream I was glad I was wearing wellies as it was in spate and bubbling downward.  Too wide to jump and even at its shallowest crossing it was too deep to wade without getting wet, thankfully my walking boots had been left at home and even at the crossing place I chose the water almost came over the top of my wellies.  I stood in the middle of the steam and took a few photos and watched as light caught mist and played upon its delicateness, a microcosm of wonder easily missed and one that would only remain for an indefinite period.

The Nant Dolwar

Glad I wore my wellies

Once over the stream I walked up a field to a gate and out onto another narrow lane which led upto a steep ice encrusted road.  The road led to the connecting bwlch for Allt Dolanog and the next survey of the day which was in a field near to a cold looking large puddle.

Gathering data at the critical bwlch of Allt Dolanog

After gathering data at the bwlch I walked up the last few metres of road toward a gate which gave access to open hillside leading upto the summit of Allt Dolanog.  As I approached the gate three dogs scampered down the path on the opposite side and following was a smiling face belonging to Karen McMahon.  We stopped and chatted, Karen was out Nordic walking with her dogs in tow, all were enjoying the openness of countryside.

Karen moved to a small holding in this area a number of years ago and is a fully qualified Pilates and Nordic Walking instructor.  I smiled at the thought of Nordic Walking being practiced in mid-Wales and smiled again when Karen told me her surname was McMahon and that she came from Chorley in Manchester.  I joked that the walking style for mid-Wales and the surname for Lancashire both seemed out of place.  Karen runs classes in Nordic Walking and can be contacted at www.fitffarm.co.uk  have a look at her website as the walking style and Karen’s philosophy is based on fitness and good nutrition.

Great day for a Nordic Walk, Karen McMahon out with her three dogs

As we said our goodbye’s Karen headed down the lane toward Dolanog and I continued upward on a good green track toward the summit of Allt Dolanog.  This hill is covered in patches of bracken all now bronzed from the onset of winter.  I took two data sets, each from adjacent rounded bumps. By now a cooling slight breeze had picked up and bulbous cloud had appeared from the west.  Away toward the west the profiles of the higher hills were now hidden under cloud but their lower slopes of white were still clearly visible.

Gathering data at the summit of Allt Dolanog

As the Trimble was packed away I headed down toward my inward track and looked out toward Pen y Berth (SJ 081 127) a hill I had visited with Mark only a couple of months ago.  Its conifered upper slopes contrasting with lower slopes of green, all framed by a foreground of dappled bracken and a sky of radiant blue.

Looking across the Afon Efyrnwy to Pen y Berth (SJ 081 127)

Once back at my car I drove out of Dolanog and as my route back home passed over the critical bwlch of Pen y Berth I pulled over and parked at a junction and examined the lay of land.  I chose the spot for Trimble placement and gathered bwlch data which would now give an accurate drop value to the hill whose summit was surveyed two months ago.

Gathering data at the critical bwlch of Pen y Berth

Although not great in height these two hills proved a joy to be out on, and to do so in such pleasant weather was a bonus.

LIDAR image of Ffridd (SJ 084 141)

LIDAR – Postscript

Since visiting these hills full LIDAR coverage is now available.  The LIDAR (Light Detection & Ranging) technique produced highly accurate height and positional data that is now freely available for England and Wales.  Consequently the numerical details for these hills have been analysed using this technique, and where appropriate resulting in the LIDAR height and position being prioritised over that produced by the Trimble GeoXH 6000.

Survey Result:

Ffridd (significant name change)

Summit Height:  295.9m (converted to OSGM15, Trimble GeoXH 6000)

Summit Grid Reference:  SJ 08441 14114 (Trimble GeoXH 6000)

Bwlch Height:  266.3m (LIDAR)

Bwlch Grid Reference:  SJ 08281 14699 (LIDAR)

Drop:  29.6m  (Trimble GeoXH 6000 summit and LIDAR bwlch) 

Dominance:  10.01% (Trimble GeoXH 6000 summit and LIDAR bwlch) 
   

Allt Dolanog

Summit Height:  288.5m (converted to OSGM15)

Summit Grid Reference:  SJ 06784 13459

Bwlch Height:  223.4m (converted to OSGM15)

Bwlch Grid Reference:  SJ 06510 14256

Drop:  65.1m 

Dominance:  22.56%

Pen y Berth

Bwlch Height:  153.3m (converted to OSGM15)

Bwlch Grid Reference:  SJ 08679 11702

Drop:  134.2m (converted to OSGM15)  

Dominance:  46.68%

For details on the summit survey of Pen y Berth

For further details please consult the Trimble Survey Spreadsheet click {here}