Thursday, 15 January 2015

Twmpau – 1000m P30s

Hill Lists – Cymru / Wales

Twmpau – 1000m P30s

Introduction

To access the Twmpau – 1000m P30 list please click {here}


Yr Wyddfa - the highest mountain in Wales

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 1000m P30 list documents all hills in Wales that are at or above 1000m in height and below 1100m 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 – 1000m P30 list please click {here}


For many years Glyder Fawr appeared on the Ordnance Survey maps as being 999m high.  A survey conducted by G&J Surveys elevated its height to 1000.8m, with the new rounded up figure of 1001m appearing on current maps

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; Carnedd Llywelyn (SH 683 643) 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. 1025m) 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 – 1000m P30 list please click {here}


Arennig Fawr - just one of many P30s in Wales

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