Basic Levelling Surveys - Introduction

The hill names used below are those as they appear in the respective lists.  Hill name research indicates that some of the names used by John and Anne Nuttall and by Michael Dewey may be viewed as not the most appropriate.  Hopefully no confusion will arise from doing this.

This all started with three simple words ‘you’ve missed one’.  These words were spoken by Dewi Jones; the recipients of Dewi’s statement were John and Anne Nuttall.  The encounter between Dewi and John and Anne happened many years ago whilst each were walking part of the Bannau Brycheiniog (Brecon Beacon) ridge.  The ‘one’ that had been missed was the northern top of Cnicht.  Dewi had devised an ingenious method to survey the re-ascent of this hill and determine if in fact it had a minimum of 15m of drop and therefore should be included in the list of 2000ft mountains.

The ingenious method Dewi had devised was to attach a spirit level to a walking staff at a prescribed height, and from the critical bwlch to sight to a point and repeat the exercise until the summit is reached.  By doing so the vertical height from bwlch to summit can be ascertained, the method is not wholly accurate but its simplicity is remarkable and its margin of uncertainty when compared to spot heights attained by photogrammetry is extremely good.  The margin of uncertainly is acknowledged at approximately + / - 1m for 15m of vertical height gain using a basic levelling staff compared to + / - 3m for spot heights attained by photogrammetry.

After Dewi had told me of his encounter with the Nuttalls and his method of surveying, I set about cataloguing every single ring contour at or above 610m in Wales and cutting a notch at a prescribed height in one of my late father’s walking sticks to insert a level surface to hold a spirit level on it.  Armed with a list comprising a multitude of single ring contours and a walking stick I set out to try and establish if one of the most important of Welsh hill lists was definitive in its then total of 181 Welsh mountains.

The walking stick was soon replaced, firstly by a staff with a maximum 4ft height reading and secondly with a staff with a maximum 5ft height reading.  I used a small post level for vertical alignment.  Each staff was hand crafted to my specifications and served me well for a number of years.  I never used the staff as a walking implement, although they were robust enough to do so, each was employed solely for surveying.  As I used to carry the first manufactured staff in my small day rucksack it looked similar to a radio aerial as it stuck out above my head by about 2ft!  The second staff was manufactured so it could be split in to four, via three brass screw fittings and therefore easily carried in a day rucksack.

In all I surveyed over 420 ‘hills’ in Wales using this method and visited many areas of the uplands I would not have contemplated visiting if not for this rather esoteric of pastimes.  I also enjoyed every minute of every survey.

The first measuring staff was very simple and was no more than a walking stick.  It is 91cm (36") high and is able to measure a maximum 0.75m.  It has a cut notch to fit a flat surface to support a spirit level.

The second measuring staff was hand crafted to my specifications and is 142cm (56") high and is able to measure a maximum 4ft height reading.  Photo: Spirit level attached at a 1m fixed height.

The third measuring staff can be split in four for ease of carriage.  The post level is used for vertical alignment.

The third measuring staff was hand crafted to my specifications and is 169cm (66½) high and is able to measure a maximum 5ft height reading.  The manufactured staffs has a variety of specified height fittings to affix spirit levels.  Photo: The third measuring staff in process of being assembled.

The third measuring staff assembled with fixed spirit levels and post level.

Through these surveys a number of hills entered some of the more established of hill listings.  These listings and hills are:

The 2000ft mountains of Wales by John and Anne Nuttall:

Foel Meirch in the Carneddau at SH 658 637.

Castell y Gwynt in the Glyderau at SH 653 581 (entered list due to Disto laser survey and conducted due to basic levelling survey).

Carnedd y Filiast North Top in the Glyderau at SH 617 631 (entered list due to a line survey and conducted due to a basic levelling survey).

Moelwyn Mawr North Ridge Top in the Moelwynion at SH 660 452.

Waun Garnedd-y-filiast in the Arennig at SH 874 452 (entered list due to a line survey and conducted due to a basic levelling survey).

Waun Camddwr in the Aran at SH 848 207.

Waun Lefrith in Y Mynydd Du at SN 798 214.

The 500-Metre Tops of Wales – ‘The Deweys’ by Michael Dewey:

Iwerddon in the Moelwynion at SH 688 482 (status deleted due to a line survey).

Craig Nyth-y-gigfran in the Moelwynion at SH 685 464 (status confirmed due to a line survey).

Foel Fras in the Moelwynion at SH 728 481.

Moel y Gyrafolen in the Rhinogydd at SH 672 352 (status confirmed due to a Leica GS15 GPS survey).

Clip in the Rhinogydd at SH 654 329.

Cerrig yr Ieirch in the Arennig at SH 758 415 (status deleted due to a Leica 530 GPS survey).

Orddu in the Arennig at SH 963 423.

Moel yr Wden in the Arennig at SH 780 356 (status confirmed due to a line survey and a Leica 530 GPS survey).

Foel Ystrodur Fawr in the Arennig at SH 814 340.

Craig y Benglog in the Arennig at SH 805 244 (status confirmed due to a Leica 530 GPS survey).

Pen Ochr y Bwlch in the Aran at SH 809 172  (status confirmed due to Trimble Geo XH 6000 survey).

Lledwyn Mawr in Y Berwyn at SH 905 287 (status confirmed due to a Leica 530 GPS survey).

Cefn Coch in Y Berwyn at SH 923 266.

Foel y Geifr in the Tarennydd at SH 716 050.

Bryn yr Ŵyn in the Pumlumon at SN 839 925.

Esgair y Maesnant South-east Top in the Pumlumon at SN 842 856.

Cripiau South Top in the Elenydd at SN 802 828 (status confirmed due to a line survey).

Stanky Hill in the Beacon Hill at SO 163 764 (status confirmed due to Leica 530 GPS survey).

Due to these basic levelling surveys there are a number of hills that have entered the Welsh 400m listing known as Y Pedwarau and have subsequently entered other P30 listings. 

Y Pedwarau by Myrddyn Phillips and Aled Williams:

Castell in Moel Hebog at SH 559 493.

Pt. 458m, Cerrig y Myllt in the Moelwynion at SH 634 469.

Craig y Garreg-lwyd in the Moelwynion at SH 730 427.

Pt. 497m in the Rhinogydd at SH 661 303.

Pt. 477m in the Arennig at SH 758 378 (status confirmed due to Trimble GeoXH 6000 survey). 

Moel y Llan in the Arennig at SH 753 240.

Moel Ddu in the Arennig at SH 728 327.

Cerniau in the Arennig at SH 756 241.

Y Gesail in the Arennig at SH 926 437.

Pt. 416m in Y Berwyn at SJ 216 396.

Belan in Y Berwyn at SJ 222 323.

Pt. 457m in Y Berwyn at SJ 025 225.

Llannerch yr Aur in the Pumlumon at SN 863 978.

Bryn y Fedwen in the Pumlumon at SN 851 972.

Banc Bronderwgoed in the Pumlumon at SN 872 988.

Bryniau Rhyddion in the Pumlumon at SN 741 893.

Llechwedd Gwinau in the Pumlumon at SN 736 877.

Allt y Derw in the Pumlumon at SN 873 834.

Pen Llwyn-ieir in the Pumlumon at SN 883 820.

Tylcau Hill in Beacon Hill at SO 141 762 (status confirmed due to Trimble GeoXH 6000 survey).

Garreg y Gwynt in Garreg Lwyd at SN 957 776.

Drysgol in Garreg Lwyd at SN 946 744.

Pt. 407m in the Fforest Glud at SO 180 692.

Esgair Dernol in the Elenydd at SN 904 758.