Friday 13 July 2018

Mapping Mountains – Trimble Surveys – Cadair Idris



10.05.18  Castell y Bere (SH 667 085), Foel Cae’rberllan (SH 676 082), Foel Ddu (SH 697 095), Mynydd Ty’n y Fach (SH 687 097) and Craig Ysgiog (SH 684 102)

Foel Ddu (SH 697 095)

Having recently LIDARed this area I thought I had better visit, and with the weather set fine I headed to the upper Dyffryn Dysynni, a beautiful part of the country and one that I had not visited for a number of years.

LIDAR image of Foel Cae'rberllan

On my surveying agenda were two great lumps of hills; Foel Cae’rberllan and Foel Ddu, they are not great in height but are relatively prominent, placed on the western ridge of the latter is Mynydd Ty’n y Fach; a recent deletion from 400m Sub-Pedwarau and a hill whose sudden lack of status could be confirmed by the Trimble.

My first hill of the day was Castell y Bere, I had not previously visited but had wanted to for a long time.  The castle was constructed in the 1220’s by Llywelyn the Great, and as with similar constructions it proceeded to have a turbulent history, and after being besieged in 1294 it fell in to disrepair.

The connecting bwlch for the castle is located in an adjacent field and as the Trimble gathered its allotted data I stood and looked out on the profile of Craig yr Aderyn and its satellite peaks, they rose greened in early summer freshness, rounded and appealing they would lead me toward them in a few days’ time.

Gathering data at the critical bwlch of Castell y Bere

The remains of the castle are an atmospheric place, dominated by near hills it is almost hidden from view by the growth of trees on its lower slopes, and yet it is a place of history, and one that thankfully has not had the misfortune to accumulate a gift shop and kiosk, it sits and stares and stands against the passage of time.

One of two entrance gates to Castell y Bere

When in the castle ruins the ever changing play of light accentuated atmosphere with near hillsides casting light then shade, adding depth and perspective to the landscape.  Surveying its high point was periphery, but once done I retraced my inward steps to the entrance gate and proceeded on my way.

The ruins of Castell y Bere

Castell y Bere with Craig yr Aderyn in the background

A green track leads up the steep westerly slopes of Foel Cae’rberllan and as the morning’s warmth was now creeping across the land, this proved a welcome addition compared to the slight chill earlier in the day, and in time the green track led me to the small grassed and rocky knoll that makes up the summit of this hill.

The shadowed remains of Castell y Bere

Craig yr Aderyn

Gathering data at the summit of Foel Cae'rberllan

Across the intervening Nant yr Eira valley, Foel Ddu rose in a wild looking way, with its upper slopes festooned in tussock grass, between me and it was a steep descent down slopes of bluebells until the grazing fields below were reached.

Foel Ddu with Tal-y-llyn in the background

Graig Goch

My next surveying objective was the connecting bwlch which is placed beside a stone wall; due to prospective satellite disruption I found placing the Trimble atop my rucksack on top of the wall to be the most convenient way to gather data.  This involved a balancing act, but once the offset to the ground below was measured I sat beneath the wall and Trimble and spent a few minutes looking at the beauty of a caterpillar in the undergrowth as it sunned itself.

Gathering data at what I thought to be the critical bwlch of Foel Cae'rberllan

This little creature kept me amused when the Trimble was gathering data

LIDAR bwlch image of Foel Cae'rberllan with the white contour showing the position of the natural bwlch as opposed to the red contour showing the position of disturbed ground beside the wall

Another green track led up the lower south-western flank of Foel Ddu and eased passage toward the tussock laden upper part of the hill.  I was soon on top sitting in clumps of bilberry grass as the Trimble gathered data.  The sun shone and although a cooling breeze blew it felt good to be out on the hill, and there were few places where I would have rather been.

The great bulk of Foel Cae'rberllan rising above the Nant yr Eira

Gathering data at the summit of Foel Ddu

Slightly easier passage on the northern side of the fence that follows the western ridge of Foel Ddu led toward the connecting bwlch, and once this was Trimbled I headed for the summit.

As the Trimble gathered data at the summit of Mynydd Ty’n y Fach I looked out to the wild surrounds of the Nant Pencoed, a great expanse of tussock and heather laden bog, it sat quietly tranquil, probably seldom visited except by a farmer.

Gathering data at the summit of Mynydd Ty'n y Fach

The bog laden expanse of Nant Pencoed

Only one hill remained to visit and survey; Craig Ysgiog, the outlier of Foel Ddu, and this gave stunning views down the flat bedded expanse of Dyffryn Dysynni past the rounded profile of Craig yr Aderyn to the coast beyond.

The cairn atop Craig Ysgiog

Dyffryn Dysynni

By now the cloud that had built and then thinned had disappeared and the hills were bathed in late afternoon glow, giving a beautiful colour to the land.  I followed an old path down the hill, only diverting from it when confronted by a grazing heard of Welsh Blacks who looked inquisitively toward me.

The Welsh Blacks

The path led toward the country lane which would lead me back to my car at Llanfihangel-y-Pennant, it had been a good time on the hill with a lazied feel to the late afternoon amongst quiet surrounds in the beautiful upper part of the Dysynni valley.

Llanfihangel-y-Pennant



Survey Result:



Castell y Bere

Summit Height:  65.1m (converted to OSGM15)

Summit Grid Reference:  SH 66760 08524

Bwlch Height:  39.3m (converted to OSGM15)

Bwlch Grid Reference:  SH 66940 08582

Drop:  25.8m

Dominance:  39.68%





Foel Cae’rberllan

Summit Height:  380.1m (converted to OSGM15, Trimble GeoXH 6000)

Summit Grid Reference:  SH 67628 08207 (Trimble GeoXH 6000)

Bwlch Height:  168.3m (LIDAR)

Bwlch Grid Reference:  SH 68815 08306 (LIDAR)

Drop:  211.8m (Trimble GeoXH 6000 summit and LIDAR bwlch)

Dominance:  55.73% (Trimble GeoXH 6000 summit and LIDAR bwlch)





Foel Ddu

Summit Height:  448.0m (converted to OSGM15)

Summit Grid Reference:  SH 69737 09550

Drop:  c 130m

Dominance:  29.01%





Mynydd Ty’n y Fach

Summit Height:  408.4m (converted to OSGM15)

Summit Grid Reference:  SH 68787 09703

Bwlch Height:  389.5m (converted to OSGM15)

Bwlch Grid Reference:  SH 69043 09685


Dominance:  4.63%





Craig Ysgiog

Summit Height:  324.8m (converted to OSGM15)

Summit Grid Reference:  SH 68403 10288

Bwlch Height:  306.9m (converted to OSGM15)

Bwlch Grid Reference:  SH 68492 10122

Drop:  17.9m

Dominance:  5.52%









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