Mapping Mountains – Trimble Surveys – Bannau Brycheiniog

30.06.18  Waun Rydd (SO 062 206 [only bwlch surveyed SO 031 205]), Fan y Big (SO 036 206), Gwaun Cerrig Llwydion (SO 041 196) and Craig Gwrelyg (SO 055 203)

Gwaun Cerrig Llwydion (SO 041 196)

With the weather set fine I was spurned in to surveying action and headed south to the sublime peaks of Bannau Brycheiniog.  Although I had three hills and another’s bwlch planned to survey it was Fan y Big above all others that drew my attention.  This hill is currently listed as a Simm and Hewitt, with 600m and 2,000ft their respective qualifying heights and 30m their minimum drop, with both lists authored by Alan Dawson.

Fan y Big is positioned on the main Bannau Brycheiniog ridge and is situated east of Cribyn and to the west of Waun Rydd, with both of these hills being higher, however Fan y Big has an appealing summit with great sweeping drops in to Cwm Cynwyn and Cwm Oergwm and a narrowing grassy north ridge that leads direct to its summit. 

Its current status as both a Simm and Hewitt is border line as it is listed with 30m of drop, which is the minimum required for these classifications, with this drop value based on the 719m summit spot height on the Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer map and the 689m bwlch spot height on the Ordnance Survey Interactive Coverage Map hosted on the Geograph website.

Although this hill has always been a marginal P30, to my knowledge it was John Kirk who first petitioned for this hill to be accurately surveyed as he doubted its P30 status, his doubts seemed to have been proven correct when I asked Aled to analysis this hill with LIDAR, resulting in a 28.2m drop, which is insufficient for both Simm and Hewitt status, Alan was notified of Aled’s LIDAR analysis and hoped to visit the hill and survey it with his Leica RX1250 later in the year, this was in 2017, but the opportunity to do so did not arise.

I then reclassified this hill to a 700m Sub-Twmpau based on the result produced by Aled’s LIDAR analysis and waited for Alan to venture south on one of his Welsh surveying bonanzas.  No more was heard about Fan y Big until Tony Jenkins posted on the Tump forum a link to my 700m Twmpau Hill Reclassification post on Mapping Mountains, and this stirred me in to action, but with the weather predicted to be another warm day I needed to get an early start if I hoped to survey this and adjacent hills before the hot conditions took their toll.

I set my alarm for 3.00am and was parked on the southern side of the Beacons and walking by 5.45am.  The sky was clear blue and early morning freshness pervaded the land which was accentuated by a light breeze, bringing comfort to those of us who suffer when the hill going becomes extremely warm.

Early morning start and the way to the hill

Even at this early hour there were people heading for the hill, and more appeared as I made good progress up the contouring path beside the Taf Fechan Forest, which led on to open hillside and gained height above the Upper Neuadd Reservoir.  I had contemplated visiting Cribyn using a path from its connecting bwlch with Fan y Big, but decided that this hill could wait for another day.

Pen y Fan

At just before 7.00am the Trimble was positioned at this first bwlch which is the critical one for Waun Rydd and data being gathered, all those I had seen on the path were now heading for Cribyn and Pen y Fan and land around the bwlch was remarkably quiet for the Beacons at a weekend.  Just as the last of the 360 datum points were collected a mountain biker appeared pushing his bike up toward the bwlch, the Trimble was closed down, packed away and I was heading up the steepening path toward the summit of Fan y Big before he reached the top of the path leading to the bwlch.

Gathering data at the critical bwlch of Waun Rydd

Fan y Big has a marvellous vantage point with the higher Beacons to its west and the continuation of the main ridge to its east, its high point is easily identifiable and consists of a small grassed hummock beside the eroded path that continues down its northern ridge.  As I set the Trimble up with its internal antenna aligned with the high point of the hill the sky still shone blue but to the east Mynyddoedd Duon were battling with early morning mist and a northerly mist bank quickly headed south toward the hill.

The Trimble set-up position at the summit of Fan y Big

Mist banks over Mynyddoedd Duon

I decided that the importance of the survey constituted two ten minute data sets from the summit and also from the bwlch, and as the first summit survey neared completion the mist rolled in up each cwm to the immediate east and west.  I quickly closed the Trimble down and reactivated it for its second ten minute data set, as it beeped away collecting its individual data appoints I was treated to a beautiful scene as mist enveloped the land below and the sun from behind created a Brocken spectre on the mist below, it had been many years since I had last experienced such a treat on a hill and I stood and stared and enjoyed and savoured for many a minute as the mist forever changed and the sun disappeared to reappear again and cast another Brocken spectre below.

Gathering data at the summit of Fan y Big

Brocken spectre from the summit of Fan y Big

By the time I closed the Trimble down I felt content with my lot in the world and headed off following the ridge toward the next important survey; the critical bwlch of Fan y Big.  This proved easy to identify even without the ten figure grid reference produced by LIDAR analysis directing me to its critical point.  I again took two ten minute data sets and sat sheltered from the increasing breeze which whipped mist up from the cwm below across the ridge in delicate and fast moving formations.

Gathering data at the critical bwlch of Fan y Big

Two hills remained to be surveyed, the first of which was Gwaun Cerrig Llwydion which only just misses Uchaf status according to LIDAR analysis and a basic levelling survey I conducted many a year ago.  I left the bwlch of Fan y Big and gained height in to the freshening mist and emerged on the summit as the heat of the morning started to burn the mist away.  The summit of this hill lay close to the eroded path and another data set was gathered.

Gathering data at the summit of Gwaun Cerrig Llwydion

The bwlch of Gwaun Cerrig Llwydion is an utter contrast to that of Fan y Big and lies in a morass of flatness with dry bog, tussock and a wildness to it, I was thankful that it was free of mist and if not for the ten figure grid reference produced by LIDAR which directed me to its critical point, I could easily have been 50 metres away with my positioning for the Trimble based purely on my eye.  As the Trimble gathered its allotted data I sat on a rock and luxuriated myself in the morning sun, it was still only 9.15am and only two surveys remained.

Gathering data at the critical bwlch of Gwaun Cerrig Llwydion

Leaving the bwlch I re-joined the eroded ridge path as it sped along above the upper reaches of Cwm Oergwm toward the final summit of the day which is the high point of Craig Gwrelyg, which is listed as an Uchaf and Pellennig hill.

Gathering data at the summit of Craig Gwrelyg

As the Trimble gathered its last summit data set of the day a murky cloud bank remained to the west hiding Fan y Big and its higher neighbours, and yet the part of the ridge I was on was now bathed in sunshine which over the next 30 minutes gradually increased in strength.

All that remained was the bwlch survey for Craig Gwrelyg and again the ten figure grid reference produced by LIDAR took me down to it.  Whilst waiting for the Trimble to achieve its 0.1m accuracy level before data should be logged I chatted with a group of walkers who were out on a navigation course and asked their opinion of where this critical bwlch lay, I had conflicting opinions given me with one deciding it was placed firmly on the upward part of the hill to hill traverse!

Gathering data at the critical bwlch of Craig Gwrelyg

As I packed the Trimble away the heat had increased, but all I now faced was downhill and although the first beads of sweat were now on my brow, I set off on the path following the escarpment edge above Blaen y Glyn with an added momentum, happy in the knowledge that all planned surveys were complete and that Fan y Big had finally been accurately surveyed.

The descent route over Craig y Fan Ddu

Survey Result:

Waun Rydd 

Bwlch Height:  599.5m (converted to OSGM15)

Bwlch Grid Reference:  SO 03161 20517

Drop:  169.7m

Dominance:  22.06%

For details on the summit survey of Waun Rydd

Fan y Big

Summit Height:  716.7m (converted to OSGM15, average of three summit surveys [two on 30.06.18 and the third on 21.08.18]) (significant height revision)

Summit Grid Reference:  SO 03652 20658

Bwlch Height:  688.2m (converted to OSGM15, average of two bwlch surveys)

Bwlch Grid Reference:  SO 03773 19876

Drop:  28.5m (700m Twmpau reclassified to 700m Sub-Twmpau confirmed) (Hewitt deletion) (Simm reclassified to Subsimm)

Dominance:  3.98%

For details on the second summit survey of Fan y Big

Gwaun Cerrig Llwydion

Summit Height:  729.2m (converted to OSGM15)

Summit Grid Reference:  SO 04140 19665

Bwlch Height:  715.1m (converted to OSGM15)

Bwlch Grid Reference:  SO 04562 19624

Drop:  14.0m (500m Sub-Uchaf status confirmed)

Dominance:  1.92%

Craig Gwrelyg (significant name change)

Summit Height:  753.9m (converted to OSGM15)

Summit Grid Reference:  SO 05521 20383

Bwlch Height:  735.1m (converted to OSGM15)

Bwlch Grid Reference:  SO 05763 20570

Drop:  18.9m (Uchaf and Pellennig status confirmed)

Dominance:  2.50%

For further details please consult the Trimble Survey Spreadsheet

Mapping Mountains – Trimble Surveys – Bannau Brycheiniog

22.07.14  Allt Lwyd (SO 078 189), Waun Rydd (SO 062 206) and Bryn (SO 071 226)

The high Bannau Brycheiniog peaks from the northern slopes of Waun Rydd

After visiting Bryn Melyn (SO 109 184) we drove down to the valley and parked beside the Talybont Reservoir at SO 099 197.  Our original plan was to visit Waun Rydd and Bryn, but a quick examination of the map showed that Allt Lwyd is a Sub-Hewitt and Sub-Sim with an estimated c 28m of drop (once back home I examined the Ordnance Survey enlarged Geograph map, it has a spot height on this hill’s critical bwlch giving it 28m of drop).  Excited with the prospect of potential new Hewittdom we quickly changed our plans and headed toward Allt Lwyd.

Opposite the small pull in area a track can be followed that leads to a gate and a path then heads uphill to a small ladder stile before the open hillside.  Further east the morning’s sunshine was still baking the hills, but our ascent route was now under high cloud cover, even if this helped in lowering the temperature the ascent was still very warm.  I oozed sweat at every step and became absolutely sodden, this and the sometimes high pollen count are two major disadvantages of summer walking, but as height was gained the merest breath of breeze occasionally filtered over the land.  I set a slow but consistent pace and Mark followed a few hundred metres behind.  The land to the east started to appear with the reservoir being foreground to the long ridges of Mynyddoedd Duon.

Looking across Talybont Reservoir toward the elongated ridges of Mynyddoedd Duon

We reached a corner of a forest where I stopped and appreciated the sweep of ridge line between Allt Lwyd and Waun Rydd, the hills of Bannau Brycheiniog portray an architectural shape seldom seen anywhere else in the country as accentuated lines sweep up to truncated summits and then plunge in descending curves down to the next bwlch before ascent lines sweep back up, all repeated time and time again.

The path continues beyond the corner of the forest to the summit of Allt Lwyd, which is behind the trees on the left

Mark on the final bit of up hill leading to the summit of Allt Lwyd

The last part of the ascent is on a good path that led up to the small cairned summit, as Mark sat and enjoyed his lunch looking out toward Waun Rydd I set the Trimble up on the highest bit of land close to the small cairn and gathered ten minutes of data.

Gathering data at the summit of Allt Lwyd

After lunch we descended to the bwlch which is narrow between the valley to valley traverse and elongated between the hills.  We spent a few minutes judging where the critical bwlch was and set the Trimble up for another ten minutes of data collection.  Having had hopes that Allt Lwyd may become a new Sim and Hewitt before the ascent, once we arrived at the bwlch our hopes were somewhat dashed as we both thought the hill looked as if it only had around 25m of drop.  We’ll have to wait until the data is processed to see if our on ground estimation is more accurate than the Ordnance Survey spot heights that give the hill 28m of drop.

Gathering data at the critical bwlch of Allt Lwyd

The connecting ridge leading up to the summit plateau of Waun Rydd is rather slender in shape and sometimes steep, looking behind I focused on Mark as he made his way up with Allt Lwyd framed in the background.  To the west the escarpment edge named Gwalciau’r Cwm on the map was slowly highlighted in a patch of sunshine, a perfect enhancement to its steep sided greens.

 

Allt Lwyd (SO 078 189)

Sunlight on the escarpment edge of Gwalciau'r Cwm

Once the steep ridge is crested a number of paths give options for onward progress, we used the path that headed straight in to the slowly rising moor toward the summit of Waun Rydd.  This hill is not typical of the region as its top is plateau like, whereas other summits are comprised of truncated land of smaller area.  As height was gained on the path the land to our north came in to view and there sat Bryn, our last objective of the day.

Bryn (SO 071 226)

The high point of Waun Rydd has two distinct possibilities for its summit, with a third cairned high point that we thought lower.  Each had five minutes of data gathered from its respective high point, I favoured the most southerly option to be the highest, whilst Mark thought the central option was the true summit.

First (southern) summit option looking toward Mark on the second (central) summit option.  The result for this placement came to 768.411m at SO 06229 20546

Second (central) summit option looking toward the cairn atop the third (northern) summit option.  The result for this placement came to 769.158 at SO 06211 20645

Third (northern) summit option looking toward Mark on the second (central) summit option.  The result for this placement came to 768.541 at SO 06209 20680

On our way down to the last summit of the day; Bryn, the sun broke through as the western cloud bank slowly dispersed.  Looking westward to the higher mountains the sun had cask a metallic gleam mixing blues and grey on their profiles, but just as quickly as the colour feast materialised so did the reoccurrence of overheating with copious amounts of sweat produced in a lost hope of cooling the body.

Mixing blues with grey on the high peaks of Bannau Brycheiniog

Data was gathered at the bwlch of Bryn before we followed a sheep track up to the summit.  The Ordnance survey 1:25,000 map gives a 562m spot height at SO 071 226 and the 1:50,000 map gives a 561m spot height at SO 072 227, the latter position has a cairn on it and views across the flatlands to the north.  Both positions were Trimbled before we headed down the south-eastern flank of the hill toward a forest.

Gathering data at the critical bwlch of Bryn

Waun Rydd (SO 062 206) from the bwlch of Bryn

Gathering data at the high point of Bryn.  The result for this placement came to 561.951m at SO 07132 22696

Gathering data beside the cairn at the second option for the summit of Bryn.  The result for this placement came to 561.206m at SO 07287 22759

Once beside the conifer plantation we assessed our options and decided to head down to a stream crossing and ascend a track on the opposite side.  This descent gave us the last views of Waun Rydd in early evening light, aglow as the sun started to cast long showers.

Heading down the south-eastern flank of Bryn

Waun Rydd bathed in early evening light

The ascent on the opposite side of the stream was evil and I suffered, the track eventually led to one or two farm houses and down on to the lane that in time brought us back to the awaiting car.  This return journey seemed long as I suffered in the sun and plodded uphill on the lane as it headed toward the reservoir dam, here we rested and looked at the reflected colours in the water.  Arriving back at the car was very welcome.  Time to rest and sit down – yummy!!

Doesn't look much, but this last bit of up hill was a wee bit evil

   

 

Tor y Foel above the coloured waters of the Talybont Reservoir

Survey Result:

Allt Lwyd

Summit Height:  653.2m (converted to OSGM15) 

 

Summit Grid Reference:  SO 07860 18909

Bwlch Height:  625.4m (converted to OSGM15)

Bwlch Grid Reference:  SO 07535 19113

Drop:  27.7m  (Subsimm, Sub-Hewitt and 600m Sub-Twmpau status confirmed)

Dominance:  4.24%

Waun Rydd

Summit Height:  769.2m (converted to OSGM15)

 

Summit Grid Reference:  SO 06211 20645

Drop:  169.7m (converted to OSGM15)

Dominance:  22.06%

For details on the bwlch survey of Waun Rydd

Bryn

Summit Height:  562.0m (converted to OSGM15)

 

Summit Grid Reference:  SO 07132 22696

Bwlch Height:  530.3m (converted to OSGM15)

Bwlch Grid Reference:  SO 06718 22457

Drop:  31.6m  (Dodd, Dewey and 500m Twmpau status confirmed)

Dominance:  5.63%

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