Tuesday, 28 April 2015

Mapping Mountains – Trimble Surveys – Aran

22.04.15  Waun Camddwr (SH 848 207) and Pt. 779m (bwlch only) 

Graham approaching one of the twin summits of Waun Camddwr (SH 848 207) with Aran Fawddwy in the background
Twenty six years ago John and Anne Nuttall had their guide to the Welsh 2,000ft mountains published by Cicerone.  This book would become essential to any prospective completer of these mountains, within the book were listed 181 hills that met the minimum 15m of drop qualification.

Six years later and Dewi Jones surveyed a top just to the north of Cnicht in the Moelwynion with an ingeniously adapted walking staff; he concluded that this top should also be in the Nuttalls list.  This hill was later line surveyed by Harold Morris and Tudur Owain as having 65ft (19.8m) of drop.

A year or so later and I was fortunate to meet Dewi in the car park at Bwlch y Groes, as we chatted I spotted the Nuttalls guide in the boot of his car, he soon told me about this as yet confirmed new top and the way that he had surveyed it.  I found what Dewi had done fascinating; this coincidental encounter had ignited a spark in me, and one that is yet to be dimmed.

Within a few weeks I had manufactured a simple measuring staff and noted a multitude of points (single ring contours at or above 610m in height) and proceeded to spend the next 15 months measuring over 160 of them.  This was during 1998 and the early part of 1999, through these surveys and ones conducted by Dewi another six new tops were discovered, bringing the total upto 188.

Two hills remained of interest; Castell y Gwynt and Fronllwyd, both are in the Glyderau and both had been surveyed as having over the required 15m of drop to qualify for John and Anne’s list.  However, they had also surveyed these two hills and concluded that they had less that the requited 15m of drop.  In time both would be accurately surveyed and enter the Nuttalls list.  With these two additions the overall number of new hills added to this list and whose qualification was instigated by a basic levelling survey was now set at nine.  One of these hills is Waun Camddwr in the Aran.  I last surveyed this hill in January 1999 as having 53ft (16.15m) of drop.  The hill has three potential points vying for the highest, two are rocky and near one another, whilst the third is separated and comprises moorland, I surveyed the moorland summit as a teense higher than the rocky summits.

Having joined John and Graham in pursuit of fun and accuracy as part of G&J Surveys, and having now got a Trimble, enables all of these hills to be more accurately surveyed, hopefully all will in time.

We hadn’t surveyed a marginal Nuttall for almost a year and the time was due to get out onto the hill and see if one of these ‘new Nuttalls’ stood up to a line survey and a GNSS survey.  The hill we picked was Waun Camddwr.

We met in the car part toward the end of Cwm Cywarch, conditions for the day on the hill were forecast to be good, albeit it with a brisk easterly breeze.  As I set off with the tripod strapped to my 75 litre rucksack the crags of Craig Cywarch loomed overhead with an intense blue sky above.

Craig Cywarch from the upper part of Cwm Cywarch
John and Graham set off a few minutes after me, but soon caught up as we followed the green path beside the dulled and crisp bracken up toward the high cwm which would give us access to the bwlch between Waun Camddwr and its much higher south-westerly neighbour.

Looking down Cwm Cywarch with John and Graham quickly approaching
The path towards the bwlch is good with a solid footbridge crossed about a third of the way up.  In the upper part of the cwm the ground steepens and the path weaves its way through small patches of broken ground.  By now John had pressed his motorised button and was disappearing off into the distance and I slowly followed with Graham in between.

The path ascends steeply up the cwm to the low point on the horizon on the left of the photo
Once beyond the connecting bwlch a path next to a fence can be followed with a series of wooden boards laid over intervening bog.  As John and Graham approached the first option for the summit of Waun Camddwr the blue sky towered all around with the bulk of Aran Fawddwy dominating the background view.

Approaching the first of the rocky summits
As I arrived beside the two rocky summits the wind blew and soon we had all put on extra layers of clothing.  The first thing to do was ascertain which of the two rocky summits is the higher, this was done with the level and staff with the conclusion being that the more north-easterly is 30cm higher than the south-westerly.  The lower rocky summit has a small cairn on it; both are separated by an intervening fence which forms a T-junction with the ridge fence and where a ladder stile is situated.  The higher of these two rocky summits does not possess a separate 620m ring contour on the 1:25,000 Ordnance Survey maps.  However, their enlarged mapping available on the Geograph website includes the same contouring but the fence line is correctly positioned.

Taking a reading from one rocky summit to the other
John had previously Abneyed these rocky summits and using the level and staff confirmed his previous survey, it also confirmed what John and Anne concluded ‘Head down north-west along the line of the old fence to rejoin the path which is boggy in places, but helpful planks of wood cross the worst bits.  Follow the fence left to this new top, which is on the left, just before the next fence junction.  Nagged by Myrddyn to go and have another look at this summit, we found the rocky knoll rises by 16m, though the OS have overlooked it and omitted an encircling 620m contour’.  I nagged them as this hill had appeared in their ‘Deleted Tops’ list with an estimated 12m of drop.  Sometimes persistence pays dividends.  The detail in their guide was written before the Ordnance Survey enlarged map on the Geograph website became publicly available.

We now set the level up to look over toward the moorland top where Graham had walked to and positioned the staff on a couple of points.  Roles were then reversed with Graham at the optics and John with the staff on the moorland summit.  The conclusion was that the highest of the two rocky summits was higher than the moorland top by about 27cm.

Graham with the staff on the moorland summit
Roles now reversed and Graham looks through the level toward John with the staff on the moorland summit
Our next port of call was this hill’s critical bwlch which lay between it and Aran Fawddwy.  Once there it brought back memories of when I was pottering around these and many other hills with my old measuring staff, I hadn’t investigated this bwlch for 16 years and my memory was of a heathery land with a slime infested boggy pool next to where the bwlch lay.  The land hadn’t changed much in the intervening years and considering the territory hereabouts the point of the critical bwlch was easily identified as a slight rise in a heathery gulley that fed down to the infant Camddwr to our south and into the boggy bog bog to our north.

As the Leica GS15 collected data from the critical bwlch we had some eats and I took data from an elevated rock with the Trimble which we had taken a measurement offset to, so we could compare the Leica data set to that of the Trimble.  Once all complete we started the line survey.

The Trimble gathering data on a rock near the Leica GS15 which is positioned in the heathery gully at the critical bwlch
Graham and John with the Leica GS15 at the bwlch of Waun Camddwr
We hadn’t done a line survey as a threesome for a long time and it was good to have the opportunity to do one as the sun baked down.  John operated the level, I held and positioned the staff and Graham noted the figures.  We headed toward the wooden boards as this gave easier access.  Slowly we made progress until roughly level with where the moorland top is positioned and over the fence we climbed and proceeded to survey upto the highest point.

Graham doing the sums as we make progress with the line survey
Many years ago when I identified this moorland top as the higher of the three I had wedged the remains of a truncated fence post into the peat near to its summit, I looked for this when we arrived at its top, it had been 15 years since my last visit and the truncated fence post has long disappeared.

We took readings to a number of potential high points and found a large boulder to be the highest; we left a yellow flag beside it, as we had done with our starting position at the bwlch.

A few minutes later and we had line surveyed from the moorland summit over to the highest of the rocky summits.  Calculator in hand the sums were now done with a rather surprising result; the moorland summit was 5mm higher than the rocky summit!  This was unexpected as we had looked through the optics between the two summits when we had first arrived and measured a difference of approximately 27cm.  We checked the height difference between where the level had been placed for its last reading and the top of the rocky summit, this came to 7cm.  John then walked back with staff in hand to the moorland summit and Graham looked through the optics and said that the reading was 8cm, I looked and said 7cm, split the difference and it matched the 5mm difference we had obtained from the line survey.  We soon realised that when the initial reading had been taken to the moorland summit we had not identified the highest point and had instead just positioned the staff on a couple of points to get the general lay of the land in comparison to the highest of the two rocky summits.

On our way from the moorland summit to the higher of the two rocky summits
As the two summits were so close in height we decided to do another line survey back from the rocky summit to the moorland summit, once this was done the sums were added up and we now made the rocky summit the higher by 2mm, hee, hee!!!!

I’m not an expert on the technical aspects of the technologies being used, but these readings basically told us that we could not split what summit is the highest, so we now have a twin Nuttall top, the first time this has happened, I love stuff like this!

As John retrieved the yellow flag at the bwlch I positioned the Trimble on the rock at the summit of the moorland top for five minutes of data, we then positioned the Leica GS15 over the summit.  After a number of compulsory summit photographs I left John and Graham at the moorland summit and scampered off to get Trimble data at the rocky summit and then continued down to the connecting bwlch with the hill that the Ordnance Survey have the name of Glascwn emblazoned across its summit.

Gathering data with the Trimble from the top of the moorland summit
Graham and John beside the level at the moorland summit
John and Graham beside the Leica GS15 at the top of the moorland summit
Gathering data with the Trimble from the top of the rocky summit
The connecting bwlch comprised a large dried up bog, I placed the Trimble at its southerly end which to my eye looked higher than its northerly end, collected five minutes of data and waited for John and Graham.

Gathering data at the bwlch of Pt. 779m
All that remained was for Graham to puzzle over the 4mm and 2mm readings and for us to reverse our steep inward route back to the cars in the valley below.  A very fulfilling and enjoyable day on the hill and a great twin Nuttall result – YYIIIPPPEEEEEE!!!!!!!!

Descending our inward route back to the valley below

Survey Result:

Waun Camddwr

Summit Height (moorland summit):  621.6m (converted to OSGM15, Trimble) 621.7m (converted to OSGM15, Leica GS15)

Summit Height (rocky summit):  621.5m (converted to OSGM15, Trimble) 621.7m (converted to OSGM15, Leica GS15)

Summit Grid Reference (moorland summit):  SH 84828 20709

Summit Grid Reference (rocky summit):  SH 84726 20550

Bwlch Height:  606.1m (converted to OSGM15, Trimble) 606.3m (converted to OSGM15, Leica GS15)

Bwlch Grid Reference:  SH 85069 20707

Drop:  15.5m (Trimble) 15.4m (Leica GS15) 15.5m (Line Survey) (Nuttall and Uchaf status confirmed)

Dominance:  2.48%

Pt. 779m

Bwlch Height:  564.1m (converted to OSGM15)

Bwlch Grid Reference:  SH 84139 19997

Drop:  215m

Dominance:  27.60%

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

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