Bagging the Welsh P30s – An Epic Hill List - UKHillwalking article

Bagging the Welsh P30s – An Epic Hill List

 UKHillwalking Article

UKHillwalking recently published an article praising the virtues of P30s and the completion of my 1000^th Welsh P30 on Bryn y Fan.  The original article and a link to it on the UKHillwalking website appear below.

Bagging the Welsh P30s - An Epic Hill List

by  Myrddyn Phillips 29/May/2017

With over 2300 entries in Wales alone, the P30s are one of the more challenging of hill lists. Though the Welsh P30s have yet to be completed, hill height expert Myrddyn Phillips has ticked off an impressive 1000. To mark this milestone, he explains here the definition and origins of the P30s, and also their attraction.  

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Bryn y Fan – completing 1000 Welsh P30s

I’d purposely avoided visiting Bryn y Fan for many years as I thought it would eventually make an ideal hill on which to complete my 1000th Welsh p30. It has a large car park, a well maintained path to its summit and is relatively close to where I live. It is also a prominent hill and is listed as a Marilyn and Pedwar; providing the weather gods were kind its summit would give extended views.

Fourteen of us met in the car park at the base of Bryn y Fan at 12.00 midday on Saturday 15th April, many being friends who I’ve shared past hill celebrations with, others friends who I’d never visited a P30 with before. Old and new felt fitting for such an occasion.

Myrddyn (left) with Alex Cameron on Bryn y Fan.  Photo:  Charlie Leventon

As we set off the last of the morning’s showers disappeared into a clearing sky, and although a chill wind blew it would remain dry for the duration of our walk; the weather gods were indeed being kind.

A green track led down from the car park under the earthen sides of the Bwlch-y-gle dam before heading up the slopes of Bryn y Fan.  As we gained height Llyn Clywedog glimmered below as with patches of whiteness now developing in the sky. Across the intervening valley the shapely profile of Bryn y Tail stood proud. The green track continued toward the upper part of the hill which consists of heath and moor, only diverting from the summit just below it, and therefore we continued on a sheep path to the high point.

This is a small rocky knoll a few metres from its trig pillar. As I walked toward it some of my companions formed an arch with their walking poles for the ceremonial last few metres to the summit. This was the first time I’d walked through a ceremonial arch of walking poles, and I quite enjoyed it!

Reaching the top was the fulfilment of many years of hill walking and it was good to share it with so many friends. As photographs and videos were taken I called Alex Cameron over as he had achieved his 1000th Welsh P30 about an hour before our ascent of Bryn y Fan. We stood beside the summit, posed for a few photographs and quickly dashed down on the leeward side out of the wind to de-camp for drinks and lots of cake.

It had been an excellent day and my thanks to everyone who attended. It was good to share my 1000th Welsh P30 with such good friends.

"My approach only chipped away on the periphery, with other things, such as life, occasionally getting in the way of major hill bagging activity..."

Autumnal light on Aran Fawddwy

So what is a P30 anyway?

P30 is an abbreviated term for hills that have 30m minimum prominence, with the ‘P’ standing for ‘Prominence’ and the ‘30’ standing for 30m.

Simply put, prominence is the vertical height gain between col and summit, or to put it more fully the height difference between summit and col connecting the hill to the next higher summit along the watershed.

The term prominence is relatively new in Britain, with its use having been adopted from prominence based groups in America. Prominence is also referred to in Britain as ‘drop’ or 'reascent’, with the former being the drop in height from summit to col, and the latter being the height from col to summit.

Using prominence in a hill list’s criteria gives the list compiler a useful tool to differentiate between one hill’s inclusion on a list over and above another's, bringing objectivity to what could otherwise becoming a subjective judgement.

Use of prominence has shaped most hill lists, and although list compilers have experimented with many other forms of qualification, including remoteness and dominance, the popularity of using prominence speaks for itself. In short, it works and it produces listings that are understood and popular for the hill bagger.

Allt Dolanog on a quiet frosty morning

The origins of P30s

The use of prominence (albeit by any other name) was established when early hill list compilers such as John Rooke Corbett (1) and Edward Moss (2) used single ring map contours to differentiate between one hill’s inclusion and another. This was then developed in 1925 by Carr and Lister (3) using 100ft minimum prominence describing it as; ‘if it rose by more than 100 feet above the lower ground connecting it with any greater height’. By using P100ft Carr and Lister paved the way for this imperial height to be subsequently used by its nearest whole numbered metric equivalent of 30m.

In 1984 the use of P30m was first employed by Terry Marsh (4); and subsequently used by many other list authors including Michael Dewey (5), Alan Dawson (6), Myrddyn Phillips (7), Clem Clements (8) and Mark Jackson (9). By doing so each in turn is following an imperial height value that has been metricised. Although imperial measurement is only used by a few nations worldwide there is an erroneous quaintness about this that seems to predominate many British listings as we rely upon it even when listing hills using metric measurement!

Approaching the Carneddau from Cwm Pen Llafar

Pushing the boundaries

Listing hills can become an addiction; there is eloquence to the procedure and fulfilment of purpose as each height band and contour checked produces another qualifying hill on the list. This procedure is time consuming, yet it can be therapeutic in its complicated simplicity. The procedure of using P30 has produced popular listings and pushed the boundaries of map study, which took many years of laborious work and which was conducted by a few dedicated people. 

A brief synopsis of published lists using P30m follows:

Terry Marsh – Welsh P30s at and above 600m in height

Michael Dewey – English, Manx and Welsh P30s at and above 500m and below 2000ft (609.6m) in height

Alan Dawson – Scottish, English and Welsh P30s at and above 600m in height (accumulated from various personal listings).

Myrddyn Phillips – English, Manx and Welsh P30s at and above 400m and below 500m in height.  Welsh P30s at and above 30m and below 400m in height.

Clem Clements – Scottish, English and Welsh P30s at and above 300m in height and below 600m in height.

These listings by Michael Dewey, Alan Dawson, Myrddyn Phillips (that's me!) and Clem Clements formed the bulk of the Tumps (thirty metre prominences and upward) that Mark Jackson duplicated when he collated the listing of Tumps in 2009. This list finally combined the other P30 lists under one title, and resulted in 16,800 British hills with their number increasing on a near weekly basis as new hills are added.  

Sunset beside Ynys Enlli from the end of the Llŷn peninsula

Personal achievement

I started bagging Welsh P30s 17 years ago, concentrating on the Deweys, and later the Pedwar hills (see UKH article here). However, these and their higher counterparts of Welsh Hewitts are mere sub lists within the whole. 

When the remaining Welsh P30 lists were published in 2004 I knew a mainland completion was feasible. With over 2300 P30s, Wales lends itself to this. Some are on islands which pose their own access difficulties, but setting these aside leaves a mainland completion that will one day, no doubt, be achieved. I did wonder if I could attain this but my approach only chipped away on the periphery with other things, such as life, occasionally getting in the way of major hill bagging activity. Nevertheless my total crept upward and toward the end of 2015 I checked my bagging journals against all my updated lists and my total was just over 960. A number of unplanned events meant that a September 2016 finish for my 1000 Welsh P30 was postponed to April of this year.

Praising the P30s

Visiting smaller heighted Welsh hills whose prominence is at least 30m has opened great swathes of the country that I love, and otherwise would not have visited if not for this esoteric hobby.

It is difficult to pick favourites as memories of good days on the hill abound, many of which have been spent with friends; however it is memories that concentrate on small detail that come to the fore, such as the high Aran when illuminated with late autumnal light, and the early sun silhouetting my local hills of the Breiddin, or the slow sinking of the sun beside Ynys Enlli from the end of the Llŷn peninsula. Such experiences are vivid and leave a fleeting sense of awe.

My pursuit of Welsh P30s has been enhanced of late by visiting islands and also surveying many marginal candidates with the Trimble GeoXH 6000, which is a versatile piece of highly accurate equipment. Using the Trimble has promoted and also demoted a great number of hills from P30 status. Visiting islands and establishing an accurate summit height has proved fulfilling and also adventurous, and both were combined on Ynys Fach, which is a tidal island attached to the Pembrokeshire coast. A near vertical descent to the island’s connecting land bridge scouted by Rob Woodall who is the leading British P30 bagger, gave an adventurous ending to a day consisting of visiting a number of islands including The Smalls which are the furthest westerly land mass in Wales, with the evening’s activities resulting in Ynys Fach being deleted from P30 status.

An early winter's morning on the summit of Cnicht

The acceptance of man-made or artificial hills by many in the hill bagging community has led to a multitude of new entries to P30 listings, with some such as Bersham Bank (SJ311481) and Pandy Bank (SJ336538) being the result of stabilised waste spoil from old mining activity, whilst Y Ceiliog Mawr (the big cockerel) (SH594598) is an impressive lump of rock left in situ in the slate mines close to Llanberis and poses a major problem to Welsh P30 mainland completion.

However, above all is the memory of winter and those days that strike a chilled crispness when snow embeds the land and the hills take on a magical quality unlike any other, memories of an early morning on Cnicht when the world seemed at peace and the dash of a dog fox brought colour to an otherwise white land, or the approach to the high Carneddau from Cwm Pen Llafar and the quiet solitude of Carnedd y Filiast in the Arenig after hours of breaking trail through deep snow, all of these memories will last a lifetime.

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Footnotes

1911 John Rooke Corbett ‘Twenty-Fives’ published by the Rucksack Club Journal (1)

1933 Edward (Ted) Moss ‘Some New Twenty-Fives’ published by the Rucksack Club Journal (2)

1940 Edward (Ted) Moss ‘The Two-Thousands of Wales’ published by the Rucksack Club Journal

1925 Herbert R C Carr and George A Lister ‘The Mountains of Snowdonia’ published by John Lane The Bodley Head Limited of London (3)

1984 Terry Marsh ‘The Summits of Snowdonia’ published by Robert Hale (4) 

1985 Terry Marsh ‘The Mountains of Wales’ Hodder and Stoughton

1995 Michael Dewey ‘Mountain tables’ published by Constable (5)

1995 Alan Dawson ‘The Murdos’ published by TACit Tables (6)

1997 Alan Dawson ‘The Hewitts and Marilyns of Wales’ published by TACit Tables

1997 Alan Dawson ‘The Hewitts and Marilyns of England’ published by TACit Tables

1999 Alan Dawson ‘Corbett Tops and Corbetteers’ published by TACit Tables

2004 Alan Dawson ‘Graham Tops and Grahamists’ published by TACit Tables

2002 Myrddyn Phillips ‘400m hills of England, Isle of Man and Wales’ published on the RHB Yahoo Group file database, with subsequent publications in 2004 ‘The Welsh 400 Metre Peaks’ on v-g.me website and 5everdene website, following co-authored with Aled Willams 2013 ‘Y Pedwarau’ by Europeaklist, 2014 ‘Y Pedwarau’ by Haroldstreet and 2017 ‘Y Pedwarau’ by Mapping Mountains (7)

2004 Myrddyn Phillips ‘The Welsh 300 Metre Peaks’ (and 2006 published on the RHB Yahoo Group file database) , ‘The Welsh 200 Metre Peaks’, ‘The Welsh 100 Metre Peaks’ and ‘The Welsh 30m – 99m Peaks’ published by v-g.me website and 5everdene website

Dates of publication unknown (to me) Clem Clements produced P30 listings to the 300m – 500m hills of Scotland, England and Wales with a variety of other prominence based listings also compiled (8)

2009 Mark Jackson ‘Tumps’ published on the RHB Yahoo Group file database (9)

The original article published on the UKHillwalking website

Twmpau - 500m P30s

Hill Lists – Cymru / Wales

Twmpau – 500m P30s

Introduction

To access the Twmpau – 500m P30 list please click {here}

The wooded summit of Moel Emoel (SH 937 402) in the Arennig range - one of the 500m Twmpau hills

The first published lists to the P30 hills under the 500m height band were made available on Geoff Crowder’s v-g.me website in 2002 and 2003.  These hills appeared in five separate lists and were split into 100m height bands.  As their titles imply the listings are to hills in Wales; they are:

The Welsh 400 Metre Peaks

The Welsh 300 Metre Peaks

The Welsh 200 Metre Peaks

The Welsh 100 Metre Peaks

The Welsh 30-99 Metre Peaks

These listings were envisaged as part of an accumulated list taking in eleven separate lists in all.  The remaining six lists are to the 100m height bands above 500m with the final list being to the Welsh 1000m P30 hills.  Although these lists were prepared for publication, they were never submitted as their respective hills had already been published in the combined lists of the Deweys and Hewitts, which were available on Geoff’s v-g.me website.

The advent of the Mapping Mountains blog now enables me to fulfil my original concept and publish the six remaining lists.

The accumulated list taking in all eleven 100m height band lists and therefore all the Welsh P30s has now been named ‘Twmpau’.  The Welsh word ‘twmpath’ is translated as ‘hillock’, which is an apt description for many of the hills in the combined list, and has been used as ‘twmp’ in certain parts of Wales, with the literal translation of the word being ‘tump’.  Although the Welsh word twmp forms part of this list’s name, the name ‘Twmpau’ is an acronym and stands for ‘thirty welsh metre prominences and upward’.  This title also pays due deference toward the name and acronym coined by Gary Honey and Jon Foote respectively for the list by Mark Jackson that was made available on the Yahoo Group RHB file database in 2009, which relied upon much of its data for Welsh hills from the lists published on Geoff Crowder’s v-g.me website and the RHB file database.

Brief History:

Many Welsh hill lists evolve from their previous counterparts and the Twmpau is no different as the use of 30m, or its whole numbered imperial equivalent of 100ft can be traced back to 1925 when Carr and Lister used 100ft of drop in their list to ‘The Mountains of Snowdonia’.  It would be another 59 years before Terry Marsh used the metric whole numbered equivalent of 30m as a drop value in ‘The Summits of Snowdonia’.  Others have followed, some of note are Tony Blackburn (1985, The 500 Metre Tops of England and Wales), Kevin Borman (1990, The Mountains of Wales), Alan Dawson (1992, The Absolute Summits of England and Wales [Sweats] later to become; 1997, The Welsh Hewitts) and Michael Dewey (1995, The 500-Metre Tops of England and Wales).

The above P30 listings were expanded downwards in absolute height by ‘Clem’ Clements and Myrddyn Phillips, who worked independent of one another.  Clem listed down to 100m in absolute height and included Sub hills down to P27m, whilst Myrddyn listed down to 30m in absolute height and included Sub hills down to P20m.  The first of these independently compiled lists to be published were the Myrddyn Phillips lists, appearing on Geoff Crowder’s v-g.me website, with the 400m P30 list also appearing on the RHB file database.  This was eventually followed by the uploading of ‘Clem’ Clements’ lists on the file database of the RHB Yahoo Group.  It was these two lists that formed the basis for the majority of Welsh Tumps listed by Mark Jackson in 2009.

Much of this data concerned hills that were unnamed on current maps and were in fact, listed by names invented by the hill list author.  Unfortunately, many of these names as a result, found their way into the current listing of the Tumps.  The names of hills listed in the Twmpau will not rely upon invented names that have no local or historical evidence of use and the author will endeavour to use the most appropriate composition for each hill name.

In summary, the first published lists using 100ft / 30m of drop appear below, all except for the Carr and Lister publication use height bands that are within the Twmpau.  These lists were compiled by:

1925    Carr and Lister    The Mountains of Snowdonia.  2,000ft minimum height with 100ft minimum drop.

1984    Terry Marsh    The Summits of Snowdonia.  600m minimum height with 30m minimum drop.

1985    Terry Marsh    The Mountains of Wales.  600m minimum height with 30m minimum drop.

1995    Michael Dewey    Mountain tables    The 500-Metre Tops of England and Wales.  500m minimum height with 30m minimum drop.

2002    Myrddyn Phillips    The Welsh 400 Metre Peaks.  400m minimum height with 30m minimum drop.

2003    Myrddyn Phillips    The Welsh 300 Metre Peaks.  300m minimum height with 30m minimum drop.

2003    Myrddyn Phillips    The Welsh 200 Metre Peaks.  200m minimum height with 30m minimum drop.

2003    Myrddyn Phillips    The Welsh 100 Metre Peaks.  100m minimum height with 30m minimum drop.

2003    Myrddyn Phillips    The Welsh 30-99 Metre Peaks.  30m minimum height with 30m minimum drop.

The 500m P30 list documents all hills in Wales that are at or above 500m in height and below 600m in height, to qualify for the main list each hill requires a minimum of 30m of prominence.

Any accompanying Sub-List includes all hills in Wales that have a minimum of 20m of drop but are not known to attain the minimum 30m of drop to enter the main list.

To access the Twmpau – 500m P30 list please click {here}

The list consists of the following:

Group:  Each hill appears under their Group, this is the group / range that the hill is a part of.  For example; Moel Wnion (SH 649 697) is part of the hill group known as the Carneddau.  The Groups are arranged from north to south on a west to east orientation.

Name:  This is considered the most appropriate name for the hill with respect to the information available to the author.  Sometimes the name used does not correspond to current Ordnance Survey map spelling and composition or the name may not appear on any map.  Where no appropriate name has been discovered for the hill from any source, the Point (for example; Pt. 525m) notation is used rather than making up a name that has no local or historical evidence of use.  The Welsh place-names that appear in this list and that were sourced from Ordnance Survey mapping are reproduced as simple compositions, with hyphenated and compound names reduced to the component elements.  It must be noted that this process will on occasion result in loss of pronunciation information and as such, is not ideal.  However, this protocol has been implemented in order to simplify the composition due to the inappropriate and inconsistent hyphen use that Ordnance Survey maps are prone to.

Summit Height (m):  This gives the map height in metres of the hill above Ordnance Datum Newlyn (ODN), often referred to as sea level.  Where a height is quoted to a decimal place it implies that the hill has been surveyed by GPS / GNSS receiver (these heights may not match current Ordnance Survey map heights).  Where a ‘c’ (circa) appears preceding the height it means there is no known spot height available and the height has been estimated from contour interpolation.

1:50,000 Map:  This column gives the number or numbers of the 1:50,000 Ordnance Survey Landranger map that the summit of the hill appears on.

1:25,000 Map:  This column gives the number or numbers of the 1:25,000 Ordnance Survey Explorer map that the summit of the hill appears on.

Summit Grid Reference:  This is the ten figure grid reference (10FGR) for the summit of the hill.  This has either been produced by an accurate survey, a map spot height or when neither is available by a centralised position in an uppermost contour ring.  When the accurate survey has been conducted independent of the Ordnance Survey a (S) for ‘survey’ will appear adjacent to the 10FGR, a (TP) if the 10FGR is taken to a ‘trig pillar’, a (B) if the 10FGR is taken to a ‘bolt’ or a ‘block’, a (L) if the 10FGR is taken to the position of a ‘levelled’ height on old maps, a (HH) if the 10FGR is taken from a ‘hand-held’ GPS unit, a (SH) is the 10FGR is taken to a ‘spot height’ either on current or old maps and an (I) if the summit position has been ‘interpolated’ from contours.

Drop (m):  This column details the relative height of the hill; this is commonly referred to as ‘drop’, ‘prominence’ or ‘reascent’.  The drop is the height difference between the summit and bwlch connecting the hill to next higher ground along the watershed.  The letter ‘c’ before the drop figure signifies there is no spot height or surveyed height known for either summit or more usually, the bwlch, therefore a part of the drop figure has been estimated from contour interpolation.

Bwlch Grid Reference:  This is the ten figure grid reference (10FGR) for the bwlch of the hill.  This has either been produced by an accurate survey, a map spot height or when neither is available by a centralised position between converging hill to hill and valley to valley contours.  When the accurate survey has been conducted independent of the Ordnance Survey a (S) for ‘survey’ will appear adjacent to the 10FGR, a (L) if the 10FGR is taken to the position of a ‘levelled’ height on old maps, a (HH) if the 10FGR is taken from a ‘hand-held’ GPS unit, a (SH) is the 10FGR is taken to a ‘spot height’ either on current or old maps and an (I) if the bwlch position has been ‘interpolated’ from contours.

Bwlch Name / Feature:  This is the name that appears on the map for the bwlch or for a significant feature on the area of the bwlch.  If a name does not appear on the map the initials ‘uom’ (unnamed on map) are used.  As the use of drop as an intrinsic part of a hill list is now well established it means that the bwlch is as important as the summit in determining a drop value for the hill.  Therefore it is only appropriate that the name of the bwlch, or a significant feature on it appears in the list.  This is the first known instance where the bwlch name / feature is also included in the details within the hill list.

Bwlch Height (m):  This gives the map height in metres of the bwlch above Ordnance Datum Newlyn (ODN), often referred to as sea level.  Where a height is quoted to a decimal place it implies that the bwlch has been surveyed by GPS / GNSS receiver (these heights may not match current Ordnance Survey map heights).  Where a ‘c’ (circa) appears preceding the height it means there is no known spot height available and the height has been estimated from contour interpolation.

Notes:  This column gives details relevant to the hill.

With special thanks to Geoff Crowder and Aled Williams for past and present help and encouragement with the listing of the Twmpau.  Thanks are also due to the people who submit 10 figure grid references to the Database ofBritish and Irish Hills (DoBIH) and for DoBIH making these available for public use.

To access the Twmpau – 500m P30 list please click {here}

Moelfre in the Rhinogydd - another 500m Twmpau

This now brings to an end the monthly instalments of the 500m to 1,000m Twmpau

Twmpau - 600m P30s

Hill Lists – Cymru / Wales

Twmpau – 600m P30s

Introduction

To access the Twmpau – 600m P30 list please click {here}

Moel Cynghorion (SH 586 563) in the Yr Wyddfa range - one of the 600m Twmpau hills

The first published lists to the P30 hills under the 500m height band were made available on Geoff Crowder’s v-g.me website in 2002 and 2003.  These hills appeared in five separate lists and were split into 100m height bands.  As their titles imply the listings are to hills in Wales; they are:

The Welsh 400 Metre Peaks

The Welsh 300 Metre Peaks

The Welsh 200 Metre Peaks

The Welsh 100 Metre Peaks

The Welsh 30-99 Metre Peaks

These listings were envisaged as part of an accumulated list taking in eleven separate lists in all.  The remaining six lists are to the 100m height bands above 500m with the final list being to the Welsh 1000m P30 hills.  Although these lists were prepared for publication, they were never submitted as their respective hills had already been published in the combined lists of the Deweys and Hewitts, which were available on Geoff’s v-g.me website.

The advent of the Mapping Mountains blog now enables me to fulfil my original concept and publish the six remaining lists.

The accumulated list taking in all eleven 100m height band lists and therefore all the Welsh P30s has now been named ‘Twmpau’.  The Welsh word ‘twmpath’ is translated as ‘hillock’, which is an apt description for many of the hills in the combined list, and has been used as ‘twmp’ in certain parts of Wales, with the literal translation of the word being ‘tump’.  Although the Welsh word twmp forms part of this list’s name, the name ‘Twmpau’ is an acronym and stands for ‘thirty welsh metre prominences and upward’.  This title also pays due deference toward the name and acronym coined by Gary Honey and Jon Foote respectively for the list by Mark Jackson that was made available on the Yahoo Group RHB file database in 2009, which relied upon much of its data for Welsh hills from the lists published on Geoff Crowder’s v-g.me website and the RHB file database.

Brief History:

Many Welsh hill lists evolve from their previous counterparts and the Twmpau is no different as the use of 30m, or its whole numbered imperial equivalent of 100ft can be traced back to 1925 when Carr and Lister used 100ft of drop in their list to ‘The Mountains of Snowdonia’.  It would be another 59 years before Terry Marsh used the metric whole numbered equivalent of 30m as a drop value in ‘The Summits of Snowdonia’.  Others have followed, some of note are Tony Blackburn (1985, The 500 Metre Tops of England and Wales), Kevin Borman (1990, The Mountains of Wales), Alan Dawson (1992, The Absolute Summits of England and Wales [Sweats] later to become; 1997, The Welsh Hewitts) and Michael Dewey (1995, The 500-Metre Tops of England and Wales).

The above P30 listings were expanded downwards in absolute height by ‘Clem’ Clements and Myrddyn Phillips, who worked independent of one another.  Clem listed down to 100m in absolute height and included Sub hills down to P27m, whilst Myrddyn listed down to 30m in absolute height and included Sub hills down to P20m.  The first of these independently compiled lists to be published were the Myrddyn Phillips lists, appearing on Geoff Crowder’s v-g.me website, with the 400m P30 list also appearing on the RHB file database.  This was eventually followed by the uploading of ‘Clem’ Clements’ lists on the file database of the RHB Yahoo Group.  It was these two lists that formed the basis for the majority of Welsh Tumps listed by Mark Jackson in 2009.

Much of this data concerned hills that were unnamed on current maps and were in fact, listed by names invented by the hill list author.  Unfortunately, many of these names as a result, found their way into the current listing of the Tumps.  The names of hills listed in the Twmpau will not rely upon invented names that have no local or historical evidence of use and the author will endeavour to use the most appropriate composition for each hill name.

In summary, the first published lists using 100ft / 30m of drop appear below, all except for the Carr and Lister publication use height bands that are within the Twmpau.  These lists were compiled by:

1925    Carr and Lister    The Mountains of Snowdonia.  2,000ft minimum height with 100ft minimum drop.

1984    Terry Marsh    The Summits of Snowdonia.  600m minimum height with 30m minimum drop.

1985    Terry Marsh    The Mountains of Wales.  600m minimum height with 30m minimum drop.

1995    Michael Dewey    Mountain tables    The 500-Metre Tops of England and Wales.  500m minimum height with 30m minimum drop.

2002    Myrddyn Phillips    The Welsh 400 Metre Peaks.  400m minimum height with 30m minimum drop.

2003    Myrddyn Phillips    The Welsh 300 Metre Peaks.  300m minimum height with 30m minimum drop.

2003    Myrddyn Phillips    The Welsh 200 Metre Peaks.  200m minimum height with 30m minimum drop.

2003    Myrddyn Phillips    The Welsh 100 Metre Peaks.  100m minimum height with 30m minimum drop.

2003    Myrddyn Phillips    The Welsh 30-99 Metre Peaks.  30m minimum height with 30m minimum drop.

The 600m P30 list documents all hills in Wales that are at or above 600m in height and below 700m in height, to qualify for the main list each hill requires a minimum of 30m of prominence.

Any accompanying Sub-List includes all hills in Wales that have a minimum of 20m of drop but are not known to attain the minimum 30m of drop to enter the main list.

To access the Twmpau – 600m P30 list please click {here}

Pen y Brynfforchog (SH 817 179) the southerly outlier of the Aran range

The list consists of the following:

Group:  Each hill appears under their Group, this is the group / range that the hill is a part of.  For example; Creigiau Gleision (SH 729 615) is part of the hill group known as the Carneddau.  The Groups are arranged from north to south on a west to east orientation.

Name:  This is considered the most appropriate name for the hill with respect to the information available to the author.  Sometimes the name used does not correspond to current Ordnance Survey map spelling and composition or the name may not appear on any map.  Where no appropriate name has been discovered for the hill from any source, the Point (for example; Pt. 625m) notation is used rather than making up a name that has no local or historical evidence of use.  The Welsh place-names that appear in this list and that were sourced from Ordnance Survey mapping are reproduced as simple compositions, with hyphenated and compound names reduced to the component elements.  It must be noted that this process will on occasion result in loss of pronunciation information and as such, is not ideal.  However, this protocol has been implemented in order to simplify the composition due to the inappropriate and inconsistent hyphen use that Ordnance Survey maps are prone to.

Summit Height (m):  This gives the map height in metres of the hill above Ordnance Datum Newlyn (ODN), often referred to as sea level.  Where a height is quoted to a decimal place it implies that the hill has been surveyed by GPS / GNSS receiver (these heights may not match current Ordnance Survey map heights).  Where a ‘c’ (circa) appears preceding the height it means there is no known spot height available and the height has been estimated from contour interpolation.

1:50,000 Map:  This column gives the number or numbers of the 1:50,000 Ordnance Survey Landranger map that the summit of the hill appears on.

1:25,000 Map:  This column gives the number or numbers of the 1:25,000 Ordnance Survey Explorer map that the summit of the hill appears on.

Summit Grid Reference:  This is the ten figure grid reference (10FGR) for the summit of the hill.  This has either been produced by an accurate survey, a map spot height or when neither is available by a centralised position in an uppermost contour ring.  When the accurate survey has been conducted independent of the Ordnance Survey a (S) for ‘survey’ will appear adjacent to the 10FGR, a (TP) if the 10FGR is taken to a ‘trig pillar’, a (B) if the 10FGR is taken to a ‘bolt’ or a ‘block’, a (L) if the 10FGR is taken to the position of a ‘levelled’ height on old maps, a (HH) if the 10FGR is taken from a ‘hand-held’ GPS unit, a (SH) is the 10FGR is taken to a ‘spot height’ either on current or old maps and an (I) if the summit position has been ‘interpolated’ from contours.

Drop (m):  This column details the relative height of the hill; this is commonly referred to as ‘drop’, ‘prominence’ or ‘reascent’.  The drop is the height difference between the summit and bwlch connecting the hill to next higher ground along the watershed.  The letter ‘c’ before the drop figure signifies there is no spot height or surveyed height known for either summit or more usually, the bwlch, therefore a part of the drop figure has been estimated from contour interpolation.

Bwlch Grid Reference:  This is the ten figure grid reference (10FGR) for the bwlch of the hill.  This has either been produced by an accurate survey, a map spot height or when neither is available by a centralised position between converging hill to hill and valley to valley contours.  When the accurate survey has been conducted independent of the Ordnance Survey a (S) for ‘survey’ will appear adjacent to the 10FGR, a (L) if the 10FGR is taken to the position of a ‘levelled’ height on old maps, a (HH) if the 10FGR is taken from a ‘hand-held’ GPS unit, a (SH) is the 10FGR is taken to a ‘spot height’ either on current or old maps and an (I) if the bwlch position has been ‘interpolated’ from contours.

Bwlch Name / Feature:  This is the name that appears on the map for the bwlch or for a significant feature on the area of the bwlch.  If a name does not appear on the map the initials ‘uom’ (unnamed on map) are used.  As the use of drop as an intrinsic part of a hill list is now well established it means that the bwlch is as important as the summit in determining a drop value for the hill.  Therefore it is only appropriate that the name of the bwlch, or a significant feature on it appears in the list.  This is the first known instance where the bwlch name / feature is also included in the details within the hill list.

Bwlch Height (m):  This gives the map height in metres of the bwlch above Ordnance Datum Newlyn (ODN), often referred to as sea level.  Where a height is quoted to a decimal place it implies that the bwlch has been surveyed by GPS / GNSS receiver (these heights may not match current Ordnance Survey map heights).  Where a ‘c’ (circa) appears preceding the height it means there is no known spot height available and the height has been estimated from contour interpolation.

Notes:  This column gives details relevant to the hill.

With special thanks to Geoff Crowder and Aled Williams for past and present help and encouragement with the listing of the Twmpau.  Thanks are also due to the people who submit 10 figure grid references to the Database of British and Irish Hills (DoBIH) and for DoBIH making these available for public use.

To access the Twmpau – 600m P30 list please click {here}

The Rhinogydd - a range of hills that include many P30s

Next instalment of the Twmpau due on 15^th June 2015