Mapping Mountains – Trimble Surveys – Mynydd Twr

07.09.14  Llanlleiana Park (SH 383 949), Dinas Gynfor (SH SH 391 950) and Graig Wen (SH 397 947)

Graig Wen (SH 397 947) on right of photo with Torllwyn (SH 402 948) beyond

After visiting Ynys Seiriol (Puffin Island) Alex and I headed to the north of Ynys Môn (Anglesey) to visit three P30’s that I’d wanted to investigate ever since first listing them in the year 2000.  The three hills are grouped in close proximity with their summits butting up against the northern cliffs of the island, Alex had visited the higher summit; Graig Wen and also walked the coastal path beside the other two and gave a good recommendation for all three hills.

By mid-afternoon we had found a small parking place on a grass verge adjacent to a narrow lane just to the south of the hills, near to where we had parked was a track leading to buildings named Llanlleiana and beyond were the three hills.

Within a few minutes of setting off we were at the area of the critical bwlch for one of the hills, I had pre-warned Alex that Trimbling and hill walking doesn’t necessarily fit in with everyone who enjoys the beauty of the hills.  Alex seems quite a laid back kind of guy and said not to worry as he was looking forward to seeing everything in operation and would enjoy just being out on the hill, an excellent attitude to have!

The first bwlch of the day was assessed from a couple of vantage points and once the Trimble was up and running I took a couple of photos and kept my eye on an inquisitive budding surveying cow who had taken an interest in the proceedings and was watching us from a safe distance.  Cow over enthusiasm may have coursed all manner of unwanted complications, especially if it wanted to trample the Trimble to see if it could withstand a hoof as well as a car tyre!

Gathering data at the first critical bwlch

Once data were collected we headed down the track, which was now more of a green lane, toward the coast and the remains of a chimney on the adjacent hillside with an abandoned mine building at the foot of the hill. 

From here we walked up and to the west toward the summit of our first hill.  Autumnal colours of rusted browns intermingled with the late summer greens as fern turned to bracken, these colours merged with September’s purple of heather, all subtly on show.

The mix of early autumnal colours

We were now on part of the Welsh Coastal Path with views north to an expanse of blue only broken by the nearness of Ynys Badrig (Middle Mouse) a 16m map heighted island, which gave off deep blacks and browns of sea washed rock.  The only break in the northern horizon was the occasional silhouette of a boat and the hills on the Isle of Man.

Ynys Badrig (Middle Mouse) a forlorn lump of rock

The path was stepped and led up next to a stone wall, the summit consisted of fern and grass, I placed the Trimble on its improvised tripod, set it to go and sat in the grass relaxing and soaking up the warmth of the afternoon.

Alex leading the way toward the summit of the first hill

Relaxing at the first summit as the Trimble gathers data

Alex led the way back down to the old mine buildings where the continuation of the stepped path led up with the pebbled beach of Porth Llanlleiana to our left.  As it was only late afternoon the sun had not reached the time when it gives magical colour to the land, but the hills and their cliffs still gave us dramatic views.  The path reaches close to the furthest northerly point of the island and then swings eastward, where a few metres off the path is the summit of Dinas Gynfor.

The old mine workings at the base of Dinas Gynfor

Dinas Gynfor is an ancient settlement probably of Celtic origin, the high point of which is now heather bound with a small cairn, I re-positioned a few of its small rocks and placed the Trimble on top, taking the measurement offset to ground level so it can be taken off the processed height result.

Gathering data at the summit of Dinas Gynfor

As the Trimble did its stuff we lazed in the sun and chatted, Alex telling me all about his hill bagging, this is done by public transport and by bicycle as he doesn’t drive.  Having read so much of Clem’s memoir where he also journeyed far and wide cycling from one hill to another and used trains as a means on some of the longer journeys, I thought listening to Alex was similar to reading about Clem’s life.  Certainly the lack of a car means a different approach to the hills and one that encourages longer walks and backpacks.

Once five minutes of data were collected I packed the Trimble away and we headed down to the connecting bwlch with Graig Wen.  This is above Porth Cynfor, or Hell’s Mouth in English, and is extremely tight on the hill to hill traverse, so much so that I expected the required accuracy to take upwards of twenty minutes to attain.  Again, Alex was good and did not complain and went off for a walk to peer down in to the sea, I set the Trimble up on its improvised tripod and a few minutes later it was ready to ‘Log’ data – Yiippeee!

Heading down toward Porth Cynfor (Hell's Mouth)

Gathering data at the second critical bwlch

The next bit of uphill gave us dramatic views down on to Dinas Gynfor and its headland butting out to the sea, a sturdy hill, rounded in shape and rocky to its downward plunge.

Dinas Gynfor sturdy in shape butting out to sea

Alex led the way on the coastal path and found our cut off point on a small path that took us up toward the trig pillar atop Graig Wen, on the way we passed two distinct bumps, both with their respective high points to our left as we aimed for the trig.  Once at the trig the Trimble was placed on what looked like the highest rock and gathered its customary five minutes of data. 

Gathering data beside the trig on Graig Wen.  The result came to 91.07m (converted to OSGM15)

After closing it off we sighted across to the two other bumps and decided to visit the one that looked the higher, although this point has not got a 90m contour ring, whereas the ground at the base of the trig has, we both thought it could be higher.  The Trimble was set up at the high point and data were gathered.  This point is distinctive and consists of a brownish large boulder embedded in the ground, a fine summit if it proves higher than the rocks near to the trig.

Gathering data on Graig Wen with the trig in the background above the Trimble.  The result came to 91.29m (converted to OSGM15)

We then discussed our downward options and decided upon a direct route down on to the narrow lane and within a half hour of leaving the last summit we were back at the car.  The walk had taken just over three hours with six surveys adding time spent on the hill.  These three P30’s are great little hills that I would recommend to anyone; it was also great to be in the company of Alex who filled the time with many an anecdote and has a good local knowledge of the area.

Survey Result:

Llanlleiana Park (significant name change)

Summit Height:  68.2m (converted to OSGM15) 

  

Summit Grid Reference:  SH 38337 94993

Bwlch Height:  34.2m (converted to OSGM15)

Bwlch Grid Reference:  SH 38745 94536

Drop:  34.0m 

Dominance:  49.85% (Dominant reclassified to Lesser Dominant)

Dinas Gynfor

Summit Height:  69.3m (converted to OSGM15)

   

Summit Grid Reference:  SH 39115 95044

Bwlch Height:  15.1m (converted to OSGM15)

Bwlch Grid Reference:  SH 39280 94837

Drop:  54.2m

Dominance:  78.21%

 

Graig Wen

Summit Height:  91.3m (converted to OSGM15, Trimble GeoXH 6000)

   

Summit Grid Reference:  SH 39734 94739 (Trimble GeoXH 6000) (summit relocation confirmed)

Bwlch Height:  41.7m (LIDAR)

Bwlch Grid Reference:  SH 41985 91871 (LIDAR)

Drop:  49.6m (Trimble GeoXH 6000 summit and LIDAR bwlch)

Dominance:  54.33% (Trimble GeoXH 6000 summit and LIDAR bwlch)

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