Mapping Mountains – Trimble Surveys – Moel Hebog

15.06.15  Castell Cricieth (SH 500 377)  

Castell Cricieth (SH 500 377)

Having surveyed Carreg yr Eryr (SH 526 378) and Moel y Gadair (SH 521 391) earlier in the day I wanted to investigate the recently elevated P30 status of Castell Cricieth.  Its P30 status was first spotted by Alex Cameron who rightly judged that with a 48m spot height appearing on the Ordnance Survey enlarged Geograph map and with bwlch contouring between c 15m – c 20m with interpolation indicating a bwlch height of c 18m, the hill that the castle sits on top of has an estimated c 30m of drop.

Having previously surveyed the heights of Castell Dinbych and Castell Caernarfon I contacted Cadw beforehand and their representative kindly permitted me to visit and survey the hill.

I parked close to the centre of Cricieth in one of the housing estates adjacent to the main street; my first objective was the bwlch which map inspection indicated to be on the town’s recreational grounds.  As I locked my car I found the area of the bwlch to have a pitch and put on it as well as a bowling green.  Thankfully the bowling green was visually lower, otherwise play for the day would have to be suspended whilst Trimbling took place.

Once on the pitch and put I assessed the lay of the land close to the 6^th fairway, rather disconcertedly there was a pitcher and putter making his way around the course and by the time I kneeled on the ground and put my chin on the grass to assess the contouring of the land, my actions had come to the attention of the bowling green assistant who I suspected would also be the person in charge of the pitch and put.  I thought this would happen and I came prepared with one of my best and friendliest smiles and explanations, he was understanding to the needs of surveying and thankfully said that it was all right for me to continue ‘as long as you don’t get hit by a golf ball’, as the pitcher and putter seemed inclined to hook many of his shots this latter piece of advice was taken on board and seemed appropriate.

The fairway on each hole consisted of closely cropped grass with the ‘rough’ between being surveyable.  This was proving great fun as I had never surveyed a pitch and put course before! 

I collected data from two initial points, one on the fairway of the 6^th and one in the rough between the 2^nd and the 5^th holes.  As the Trimble was doing its stuff I helped the pitch and putter find his wayward shot as the ball was immersed a centimetre deep in the thick rough.  I also looked up at the castle which looked rather grand perched on its hill top.

Gathering data on the 6th fairway

Gathering data in the rough between the 2nd and 5th fairways

As I packed the Trimble away I left the recreational grounds and walked through the housing estate, noting on the way that ground beside a bench next to the road looked as if it could be a teense higher, therefore if time permitted I would survey a third potential position for this hill’s critical bwlch once the castle had been surveyed.

Castell Cricieth was first constructed in the 1230’s by Llywelyn the Great and later heavily modified by the forces of Edward 1 in the late 1200’s.  It has a turbulent history with it being besieged by the Welsh in 1294 / 1295 and later re-taken by the Welsh during the years of uprising led by Owain Glyndŵr.  During the recapture of the castle it had many of its walls torn down and was set alight.  The vestiges of what survives are on show today.

Approaching the castle two proud Red Dragon’s fly above the remaining towers and the path onward leads the members of the public into the lower modern castle entrance, this is where the admittance fee is paid, I had been granted free admittance and signed their VIP book after I introduced myself to Sylvia Jones, who was expecting me.  My thanks are given to Cadw for letting me survey the castle and for giving me free admittance, this is greatly appreciated, diolch yn fawr iawn.

Approaching Castell Cricieth

As I walked up the path toward the top of the hill and the remains of the castle I looked back toward the area of the bwlch, which if not for the recreational grounds would no doubt have houses built on it, so pitch and putts can be a very helpful tool when surveying.

Thankfully the recreational grounds where the pitch and putt is situated exist, otherwise this area would no doubt have houses built on it and therefore surveying would be compromised

The castle is dramatically positioned overlooking Tremadog Bay and the sea with all but its landlocked entrance being hard to reach.  I investigated its outer southern grounds before venturing into its remains.  The highest point inside the castle was not hard to find as it was on grass under one of the walls.  I considered putting the Trimble on this point, but decided to investigate the other parts of the castle before doing so.

I exited the main entrance and walked around the eastern side which overlooks the sea, on this side of the wall were small rocky outcrops, I followed these upto their highest point, which proved to be directly on the opposite side of the exterior wall to the high point within the walls.

As the Trimble gathered data from the high point outside the walls I stood and chatted to a number of people as they passed, including a romancing couple who I apologised to as they swept each other up in their arms and I sheepishly approached trying to explain what I was about to do, thankfully they seemed interested and asked a number of questions, others were out with their dogs and guide books examining the various towers and reading about the history of the castle as they did so.

The highest rock outcrop outside the walls is diagonally opposite the high point inside the walls

Gathering data at the high point outside the walls

Once five minutes of data were gathered I headed back inside the walls and set the Trimble up on the high point inside the castle.  As it slowly ebbed down to its 0.1m accuracy level before data can be logged, I had a brief look at the exterior walls to see if they hid any natural rock outcrop in them, I could not find any so happy with my placement of the Trimble I continued to wait.

The Trimble was sitting in a bowl of walls and took a long time to reach its prescribed accuracy level, during this I chatted to Rachel who was out with her niece, they had been to Dylan’s on the seafront of the town for lunch, this is where I had a 7.15pm appointment to meet my brother and Al, Frances, Laura and Sam to celebrate Alun’s 60^th birthday.  Rachel highly recommended Dylan’s and it looked inviting from outside as I passed it earlier in the day.  We chatted for quite some time, when they left I looked at the Trimble’s screen and it was still on 0.11m, I left it another couple of minutes and the 0.1m accuracy was attained, I pressed ‘Log’ and scampered off to wait for five minutes as it collected its data.

Gathering data at the high point inside the walls

Leaving the castle I thanked Sylvia and walked back down the road toward my car and the area of this hill’s bwlch.  I looked at the continuing downhill on the valley to valley traverse which went through a locked and closed off gate, I then chose my spot and placed the Trimble down on a patch of grass beside a bench and waited and waited and waited.  I was in no rush and spoke to a few people as they passed, one explained that the gate had once given access down a public footpath but had been closed off as someone had died there after having lying at the back of houses overnight, I also encountered three lost French tourists who were looking for their car, this was parked next to the sea and they were walking toward me which was heading inland, I tried my stumbling French (non-existent) and pointed them back toward the sea.

The last data set of the day at the critical bwlch of Castell Cricieth

Aha, bril, 0.1m, press ‘Log’ and quickly scamper off, five minutes later I switched the Trimble off, packed it away and sauntered back to my car to get my boots off.  A few minutes later I was parked above the town in a lay-by and changed from my walking gear into my smart let’s get a lot of nosh in my tummy gear.  I even had time to relax in the early evening sun and have a read for 45 minutes.  Next stop Dylan’s and Alun’s 60^th.

Alun, Laura, Sam and Frances outside Dylan's

Survey Result:

Castell Cricieth

Summit Height:  49.6m (converted to OSGM15)

Summit Grid Reference:  SH 50003 37733

Bwlch Height:  19.3m (converted to OSGM15)

Bwlch Grid Reference:  SH 49943 38015

Drop:  30.3m (30-99m Twmpau status confirmed)

Dominance:  61.02% (Dominant addition confirmed)

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

Mapping Mountains – Trimble Surveys – Glyder Fawr

01.03.15  Castell Caernarfon (SH 478 626)

Castell Caernarfon (SH 478 626)

Castell Caernarfon stands as an imposing stone structure beside the Afon Seiont as it flows toward the waters of the Menai Strait.  Nowadays the Castle is maintained by Cadw, which is the Welsh Government’s historic environment service.  However, when built the structure was one of imposition, a structure that was meant to impress and subjugate.

The Castle was commissioned by the then King of England; Edward 1, its cost was vast and estimated as £20,000 - £25,000.  In 1294 the natives became restless and decided that the imposition of a fortress castle on their doorstep which administered north Wales for the then English King was not on, and they sacked it.  A year later it was re-taken by supporters of the King, only to be besieged in the early 1400s by the supporters of the Glyndŵr rising.

Castell Caernarfon is one of the most impressive castles in Wales and forms but one of many that were built around north Wales by supporters of the English King.  I had only visited the inside of the castle once before, many years ago when a child and have little memory of it.  As today was Saint David’s Day, Cadw had opened all its maintained properties for free, and as there was a small matter of a rugby international being played in the afternoon we decided to visit in the morning, this would also give us a number of hours to investigate the castle before the predicted early afternoon rain set in.

There is a contrast between the exterior of the castle and its interior, outside of the stone structure the busy town of Caernarfon has grown, spreading out from the castle, whilst inside is open space with the interior buildings now gone.

The town of Caernarfon spreading out from the castle

As we walked up through one of the gateways to the castle the sheer depth of the exterior walls and their ever present arrow loops gave a forbearing but impressive start to our tour.  I’d brought the Trimble along just for the fun of it as the grounds where the castle stands have little prominence but a height reading from the high point of its interior would be a novel addition to the increasing number of points that it had surveyed.

We visited the Black Tower which is positioned just off centre in the southern walls and climbed its spiral steps for a view from the top.  To our west the Queen’s Tower and Eagle Tower rose to the sky, all connected by a series of high walkways.  Across the Afon Seiont the folly on top of Coed Helen looked down from its grassy perch.

Across the Afon Seiont towards Coed Helen

After investigating a number of walkways and large rooms we headed down to the eastern end of the castle, this is where the high ground within the walls is found, it is also where the Trimble ended up being positioned.  As it sat quietly on the grass gathering data a number of children with swords and shields played out their imaginary battles, once six minutes of data were collected I switched it off and we continued exploring the castle and climbed the Granary Tower for a view over the town and across to the towered southern walls.

Gathering data at Castell Caernarfon

Looking down on the high point of the inner castle

We ended our tour with a look in the museum and as Alun and Laura headed for the climb of the Eagle Tower, Bryn and I walked over the footbridge crossing the river outside the castle for what we hoped would be a good view of the structure.  Today the grey of stone merged with the grey of sky, the latter was now depositing the predicted rain and so we headed back to the car.

Survey Result:

Castell Caernarfon

Summit Height:  18.1m (converted to OSGM15)

Summit Grid Reference:  SH 47854 62670

Drop:  5m

Dominance:  27.60%

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

Mapping Mountains – Trimble Surveys – Mynydd Hiraethog

31.12.13  Gogarth (SH 767 833)

The summit area of Gogarth (SH 767 833)

Gogarth or the Great Orme in English, is an impressive chunk of land that buts out from the north Wales coast and is a prominent landmark for miles around.  With a one-way road encircling it and access to the summit area via two roads it can be ascended very easily and I’m afraid to say this is the way we opted for.  

As an adventurous few souls were walking rapidly around the road, taking their mornings exercise before the forecast of the late afternoons deluge ushered forth, we sneaked via motor vehicle up to the high car park and stumbled out in glorious sunshine, albeit a bit breezy in places and wandered over a bit of grass to bag the summit.  This consists of a small outcrop of rock next to the base of the trig.

The Trimble gathering data on the high point of Gogarth

Winter sunshine radiated down on us as the higher mountains were bathed in silhouetted outline.  All that was needed was a candyfloss and toffee apple to make the occasion perfect!  Tis a good vantage point though and I peered out to the north trying to convince myself that the slither of something between sea and sky was the Isle of Man.  I couldn’t convince my two colleagues who dismissed the sighting as nonsense and indicated that the Isle would be more over there, indicating somewhere toward the north-east.

The Trimble found a convenient perch and nestled in to the summit rock for seven minutes of data collection aligned with the very highest bit of natural rock (there’s a large rock plinthed panoramic viewfinder that is higher).

Bryn and Alun near the summit of Gogarth.  The large flat rock to the left of the trig pillar is the plinth with the panoramic viewfinder

This is the second Marilyn the Trimble has surveyed, with the first being Moel y Golfa (SJ 290 125).  The hill is also listed as a HuMP and a Welsh 200m P30.  The triangulation pillar’s flush bracken is given a height of 207.172m in the OS Trig Database and when aligned with the highest rock it is of similar height with the flush bracken just a little higher.

The top of the flush bracket is a little higher than the natural high point, which is the knobbly bit of rock just to the left of the trig pillar.

Survey Result:

Gogarth (significant name change)

Summit Height:  207.1m (converted to OSGM15, Trimble GeoXH 6000)

Summit Grid Reference:  SH 76749 83334 (Trimble GeoXH 6000)

Bwlch Height:  5.4m (LIDAR)

Bwlch Grid Reference:  SH 82244 78704 (LIDAR)

Drop:  201.7m (Trimble GeoXH 6000 summit and LIDAR bwlch)

Dominance:  97.41% (Trimble GeoXH 6000 summit and LIDAR bwlch)

For details on the 2nd visit to Gogarth

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

Mapping Mountains – Trimble Surveys – Moel Hebog

26.12.13  Dinas Dinlle (SH 436 564)

Dinas Dinlle (SH 436 564)

Before the customary Boxing Day Bubble and Squeak we headed down for a wander on the beach at Dinas Dinlle and watched the sea sky subtly change its grey hue as the westerly’s blew in an occasional shower.

This part of the north-west coast of Wales takes its name from the old Iron Age hill fort that overlooks the pebble beach.  Only part of this ancient structure still remains as the sea has eroded much of its western side that only a double semi-circular rampart remains.

This hill was first proposed as a P30 by Chris Watson who spotted that the Ordnance Survey enlarged mapping on the Geograph website has a small uppermost c 35m ring contour at the summit, and as the bwlch contouring is between 0 – c 5m it means this hill should have a minimum of 30m of drop.

I’d only visited once before and hold fond memories of the excursion.  Today I was accompanied by my brother; Bryn and a good friend; Alun.  The ascent from the car park next to the beach is on a good path, past an interpretive board giving the history of the site and up to the summit, which is now undergoing work to try and stabilise it.

The last few metres to the summit of Dinas Dinlle.

On my previous visit we’d looked out on a dramatic sky as the lowering sun shot beams of light from behind large sea clouds.  Today the breeze blew and families were walking the cliff edge and on the beach, with dogs running in to the water chasing tennis balls.

The highest point is easily identifiable and is part of the land that is now being stabilised.  Five minutes of data was gathered and Bryn had the honour of switching the equipment off before we ventured down to the beach for half an hours stroll.

The Trimble GeoXH 6000 on the high point of Dinas Dinlle with Bryn admiring the view.

I didn't attempt to locate the critical bwlch as more pressing matters of dinner were calling.  However, map contouring and the view from the summit suggests it is placed at SH 439 562.

Survey Result:

Dinas Dinlle

Summit Height:  34.7m (converted to OSGM15, Trimble GeoXH 6000)

Summit Grid Reference:  SH 43676 56438 (Trimble GeoXH 6000)

Bwlch Height:  4.1m (LIDAR)

Bwlch Grid Reference:  SH 43922 55774 (LIDAR)

Drop:  30.6m (Trimble GeoXH 6000 summit and LIDAR bwlch) (30-99m Twmpau addition)

Dominance:  88.22% (Trimble GeoXH 6000 summit and LIDAR bwlch) (Dominant addition)

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