Thursday, 8 December 2016

Mapping Mountains – Hill Reclassifications – Yr Uchafion


Esgair y Llyn (SN 841 701)

There has been a new addition to the listing of Yr Uchafion instigated from map study and confirmed from LIDAR data analysed by Aled Williams.  Yr Uchafion is the draft title for a list of the Welsh 500m P15s that takes in all hills in Wales at or above 500m that have a minimum of 15m of drop, the list is a joint compilation with Aled Williams.  Details relating to this list were published on the Mapping Mountains site in November 2015.

The hill is situated in the Elenydd group of hills in the central part of Mid and West Wales.  This grouping of hills forms one of the wildest in Wales and takes in some of the most remote hills in the country.  The hill is situated in an immense grassland of moor and tussocks with Llyn Cerrigllwydion Isaf to its south-east and the higher summits of Cnapyn Drawsffos (SN 834 706) to its north-west and Blaen Rhestr (SN 843 693) towards its south.  Any towns or villages are a far distance away with Ysbyty Ystwyth towards the west and Rhaeadr Gwy (Rhayader) towards the east.

The hill can be accessed from its north-east via a track that leads to the farmhouse of Glanhirin, a path then leads toward and up the north-eastern ridge of Blaen Rhestr.  However, an alternate route would be using the Monks Trod, which is an ancient route across the hills developed by the Cistercian monks as a bi-way between the abbeys of Cwm-Hir and Strata Florida.  Whichever way is chosen it leads into land that is open and somewhat featureless.

The name of the hill is Esgair y Llyn and its inclusion as an Uchaf was spotted by Aled as the Ordnance Survey enlarged mapping on the Geograph website gives this hill a 529m summit spot height and a 513m bwlch spot height, this 16m of drop is sufficient to enter the list of Uchafion. 

As Aled was analysing other hills in the vicinity against LIDAR data, he did likewise with Esgair y Llyn.  LIDAR (Light Detection & Ranging) is highly accurate height data that is now freely available for much of England and Wales, and as mentioned in the first paragraph of this post; if Esgair y Llyn has a minimum of 15m of drop it would be included in the listing of Welsh hills at or over 500m in height that has a minimum of 15m of drop, and has the working title of Yr Uchafion.

Aled’s analysis of LIDAR data gave the hill a 528.8m summit height at SN 84118 70177, and a 513.3m bwlch height at SN 83811 70087, these values give this hill 15.5m of drop which is sufficient for qualification as an Uchaf.

This now revises the total in Yr Uchafion which will be updated accordingly and the hill is now listed as an Uchaf.


The full details for the hill are:

Cardinal Hill:  Carn yr Hyrddod

Summit Height:  528.8m (LIDAR data)

Name:  Esgair y Llyn

OS 1:50,000 map:  135, 136, 147

Summit Grid Reference:  SN 84118 70177 
  
Drop:  15.5m (LIDAR data)



The reclassifications to Yr Uchafion / The Welsh 500m P15s reported on Mapping Mountains are ills of wales as follows:



UCHAF ADDITIONS


Esgair y Llyn (LIDAR data) (SN 841 701) added as an Uchaf with 15.5m of drop.



UCHAF RECLASSIFICATIONS




UCHAF DELETIONS





Myrddyn Phillips and Aled Williams (December 2016)





Wednesday, 7 December 2016

Mapping Mountains – Significant Name Changes – Y Pellennig, Yr Uchafion and 500m Twmpau


Bryn Llwyd (SN 835 920)

This is the sixty second post under the heading of Significant Name Changes, and the following details are in respect of a hill that was surveyed with the Trimble GeoXH 6000 on the 5th May 2016 and the 13th May 2016.

The hill is part of the Pumlumon range, which is an extensive range of hills in the north-western part of Mid and West Wales, and is relatively remote for a Welsh hill with the nearest small community being Penffordd-las (Staylittle) to the east.

The Trimble GeoXH 6000 gathering data at the summit of Bryn Llwyd

The listed summit of this hill has been relocated from Bryn yr Ŵyn at SN 83919 92571 to Bryn Llwyd at SN 83574 92022, with the latter surveyed with the Trimble GeoXH 6000 as being 1.5m higher.  

The hill first made an appearance in a hill list in 1997 when John Kirk listed it as Bryn Yr Wyn, using the name of the adjacent hill but with the correct grid reference in his Kirk’s BIG Mountain List, a list that remains unpublished but available via a kind request to the author.  The adjacent lower hill was later included by Michael Dewey and listed as ‘Bryn yr Wyn’ in the April 2002 edition of Strider that listed the updates to his The 500-Metre Tops of England and Wales list that appeared in his Mountain tables book published by Constable in 1995.  The summit of the Dewey was later relocated due to the Trimble survey to the higher summit and listed as Esgair Greolen.

This hill is also listed as a Pellennig, an Uchaf and a 500m Twmpau, with Y Pellennig and Yr Uchafion being co-authored listings with Aled Williams.  Prior to making local place-name enquiries the now known higher summit was accepted as being named Esgair Greolen, and since this summit has usurped its neighbour as being the higher, this is the name used in Michael’s list to The 500-Metre Tops of England and Wales.

Hill list authors are prone to list a hill by the name that appears nearest to its summit on Ordnance Survey maps, without much consideration for its local or historical confirmation, or whether map placement is appropriate.  However, place-name data can be improved by asking local people and examining historical documents, and on the way to survey this hill for the second time with the Trimble I made place-name enquiries with the local farmer, who then kindly took me up in his two seater quad bike toward the hill.  Afterward both Aled and I examined a number of historical maps for evidence of where the name of Esgair Greolen originated and where it is applicable to.

The local farmer I met is named Gareth Griffith and he had farmed from Nant-yr-hafod for forty years, he was out with his dogs heading up the hill to feed the sheep.  As we chatted I asked him about the names of the local hills, and he rolled off name after name of the local hills and streams, one in particular proved extremely interesting, it related to the hill that Ordnance Survey maps name as Esgair Greolen, which was the hill I wanted to concentrate the morning’s surveying activities on.  Gareth knew this hill as Bryn Llwyd, and said that ‘this name doesn’t appear on the map.’  I asked him about the name of Esgair Greolen, and he had never heard of it.

Gareth Griffith

Gareth gave me a lift up the hill on his two seater quad bike and dropped me off at the end of the track close to the forested summit of Fedw Ddu.  From this vantage point we were looking across to Bryn yr Ŵyn and also the hill I planned on prioritising to survey, and Gareth pointed toward each and named them, Bryn yr Ŵyn and Bryn Llwyd, the latter is the hill named as Esgair Greolen on Ordnance Survey maps.

When back home I examined old Ordnance Survey maps and forwarded the details of my meeting with Gareth Griffith to Aled, who proceeded to research where the name of Esgair Greolen originated and what feature this name may be applicable to.  Aled’s comments relating to this appear in the 2nd edition of Y Pellennig - The Remotest Hills of Wales, and are reproduced below:

The OS have applied the name Esgair Greolen to this hill since the 1901 Six-Inch map, however earlier OS maps provide conflicting information regarding the positions of the steams named Nant Esgair Greolen and Nant y Barcud, which casts uncertainty over the exact position of Esgair Greolen.  A single local contact failed to confirm Esgair Greolen as the name of this hill, but instead visually identified the hill as being known as Bryn Llwyd.

Extracts from a number of Ordnance Survey maps appear below giving detail relating to the name placement of Esgair Greolen and the steams of Nant Esgair Greolen and Nant y Barcud.

Extract from the Ordnance Survey One-Inch 'Old Series' map

Extract from the 1886 Ordnance Survey Six-Inch map

Extract from the 1903 Ordnance Survey Six-Inch map with the stream previously recorded as Nant y Barcud now recorded as the Nant Esgair Greolen


Extract from the Ordnance Survey 1903 Six-Inch map where the name Esgair Greolen first appeared on an Ordnance Survey map


Extract from the current Ordnance Survey 1:25,000 Explorer map

As a result of this research the hill has subsequently been listed under the name of Bryn Llwyd in Y Pellennig – The Remotest Hills of Wales (Europeaklist, Haroldstreet, v-g.me, Mapping Mountains and Mapping Mountains - Publications), and the 500m Twmpau list, this is the name that Gareth Griffith gave for the hill, and this name does not appear on any Ordnance Survey map.


ills of Wales, and are reproduced below@
The full details for the hill are:

Group:  Pumlumon

Name:  Bryn Llwyd

Previously Listed Name:  Esgair Greolen 

Summit Height:  501.4m

OS 1:50,000 map:  135, 136

Summit Grid Reference:  SN 83574 92022 
 
Drop:  30.3m



For details on the 1st survey and the 2nd survey of Bryn Llwyd


Myrddyn Phillips and Aled Williams (December 2016)













Monday, 5 December 2016

Mapping Mountains – Hill Reclassifications – Y Pedwarau



Moelfre (SH 717 744)

There has been a deletion of a Sub-Pedwar by analysis of LIDAR data coupled with a previous survey with the Trimble.  The hill continued to be listed as a Sub-Pedwar based on a 433.0m (converted to OSGM15) surveyed summit height and an on-site visual inspection of one of two potential positions for this hill’s critical bwlch, this option for the bwlch position was visually considered lower than the second option for the bwlch position at SH 71909 74471 which was surveyed as being 416.9m (converted to OSGM15) high.  Because of this the hill was retained as a Sub-Pedwar with an estimated drop of c 20m.  The Sub-Pedwarau are the Welsh hills at or above 400m and below 500m in height with a drop between 20m and below 30m.

The hill is positioned above the towns of Penmaenmawr to its north and Llanfairfechan to its west and can be easily accessed from a green track that continues from the end of a minor lane to the hill’s west, or from its north-west where public footpaths and bridleways lead close to its summit. 

The hill’s summit and one prospective position for its bwlch was surveyed in the late evening with Aled Williams and the hill is positioned in the northern Carneddau in north-west Wales.  This hill range comprises some of the highest mountains in the country but the evening walk concentrated on some of its 300m and 400m lower hills.

The name of the hill is Moelfre and prior to the survey with the Trimble GeoXH 6000 the height of the hill was listed as 435m.  This height appears on the Ordnance Survey 1:25,000 Explorer and 1:50,000 Landranger maps and the Ordnance Survey enlarged map on the Geograph website.  This 435m height seems to be a recent addition as the series of Ordnance Survey Six-Inch maps from 1888 - 1946 have a 1,422ft (433.4m) height, whilst the Ordnance Survey Seventh Series One-Inch map and the Historical 1:25,000 map has 1,423ft (433.7m).

Moelfre was surveyed with the Trimble GeoXH 6000 as being 433.0m (converted to OSGM15) high and one of its two bwlch positional options at SH 71909 74471 was surveyed as being 416.9m (converted to OSGM15) high, with the second bwlch positional option at SH 72253 74153 estimated as being c 413m high, which gave this hill c 20m of drop and therefore it retained its status as a Sub-Pedwar.

However, since the survey with the Trimble, Aled has analysed the bwlch position via LIDAR data, whose height we had previously estimated from a visual inspection.  LIDAR (Light Detection & Ranging) is highly accurate height data that is now freely available for much of England and Wales.  Analysing LIDAR data gave the following result:


Summit Height:  433.1m

Summit Grid Reference:  SH 71735 74416

Bwlch Height:  414.7m

Bwlch Grid Reference:  SH 72253 74153

Drop:  18.4m


The summit data produced by LIDAR is extremely favourable when compared to that produced by the Trimble GeoXH 6000, these are detailed below:


433.1m LIDAR summit height at SH 71735 74416

433.0m Trimble summit height at SH 71733 74418


Therefore, the 414.7m LIDAR data produced for the bwlch position at SH 72253 74153 that had previously been inspected visually is considered accurate and when coupled with the 433.0m summit height produced by the Trimble GeoXH 6000 gives this hill 18.3m of drop, which is insufficient for the hill to retain its Sub-Pedwar status, and therefore Moelfre is deleted from the listing of Sub-Pedwar hills and the list of Y Pedwarau will be updated accordingly.  The list of Pedwar hills is available from the Haroldstreet website.


The full details for the hill are:

Cardinal Hill:  Tal y Fan

Summit Height:  433.0m (converted to OSGM15)

Name:  Moelfre

OS 1:50,000 map:  115

Summit Grid Reference:  SH 71733 74418 

Drop:  18.3m (bwlch LIDAR data)


The list of additions, reclassifications and deletions from the 400m Sub-Pedwar list since the 1st edition of Y Pedwarau was published by Europeaklist are as follows:


SUB-PEDWAR ADDITIONS





SUB-PEDWAR RECLASSIFICATIONS








SUB-PEDWAR DELETIONS






Moelfre (SH 717 744) the deleted Sub-Pedwar



Myrddyn Phillips and Aled Williams (December 2016)









Saturday, 3 December 2016

Y Trechol - The Dominant Hills of Wales - Tarennydd


Hill Lists – Cymru / Wales

Y Trechol - The Dominant Hills of Wales

Introduction

To access Y Trechol - The Dominant Hills of Wales list please click {here}


Tarren y Gesail (SH 710 058) is situated in the Tarennydd group of hills and is listed as one of The Dominant Hills of Wales

Listings of hills in Britain have progressed since Sir Hugh Munro first compiled a list to the Scottish 3,000ft mountains that eponymously now bear his name of the Munros.  Since Sir Hugh’s list was first published in the 1891 Scottish Mountaineering Club Journal the concept of how to differentiate one hill from another has developed with this association now mainly relying upon what is referred to as prominence.  This term is also known as reascent and drop, with this being the height gain between summit and connecting bwlch to the higher parent peak via the watershed.

Although differentiating one hill from another mainly relies upon prominence, it is not the only tool used to do so, as such criterion as distance, and height and prominence combined have also been used.  But prominence is now the main criterion used to differentiate one hill from another.

The concept of prominence was first investigated by the early hill list authors such as Corbett and Moss who employed the use of a single ring contour in their listings.  This system for cataloguing hills relied upon maps of the day that were based on ring contours at 50ft intervals, therefore a hill may be included that had a 5ft prominence or less because it had a separate ring contour, this is an obvious failing in this system.

However, Corbett had initialised the concept of objective judgment in how to make this all important differentiation between one hill and another, whereas Munro relied upon subjective judgment when he differentiated between his Separate Mountains (Munros) and their Subsidiary Tops (Munro Tops).

This objective judgement took its next stage forward when Carr and Lister used a 100ft criterion to differentiate one hill from another in their book to ‘The Mountains of Snowdonia’ which was published in 1925 by John Lane The Bodley Head Limited of London.  This use of 100ft by Carr and Lister can be considered as the first objective height differentiation and therefore the first use of how we now view the term prominence.

Although, as mentioned previously, there have been other use of criterion to differentiate one hill from another, there is a definite line between how the use of prominence has evolved, this line can be viewed as a link, but this link does not have many connecting parts to it, and up until the Dominant listing that this Introduction details, that connecting part only involved one link, and that is Relative Height, and now the second connecting link of Dominance has been added.

The difference between Prominence and Relative Height can be summarised as the following, with the explanation of Dominance then following:


Prominence is applied to hills whose qualification also depends upon minimum height.


Relative Height is applied to hills whose qualification is just dependent upon a minimum prominence.


Dominance is applied to hills whose prominence equal or exceed half that of their absolute height.


For those that are not initiated with the intricacies of hill list criteria the above explanation can sometimes be a difficult concept to understand, but the essence being is that Prominence is used as part of a criteria in conjunction with another criterion which is usually Minimum Height, whereas Relative Height is normally used as a singular criterion that is not dependent upon any form of minimum height except for that stipulated for its relative height, whereas Dominance relies upon the relationship between the hill’s prominence and its absolute height and is part of a criteria in conjunction with another criterion which is Minimum Height.

The first use of what we now refer to as Relative Height in a published hill list was by Eric Yeaman in his ‘Handbook of the Scottish Hills’ which was published in 1989 by Wafaida.  However, the term Relative Height was coined by Alan Dawson for the Marilyns which were first published in ‘The Relative Hills of Britain’ book by Cicerone Press in 1992.

These two publications dispensed with the concept of Prominence with Eric Yeaman using 100m of Relative Height as the main part of his Scottish list and Alan Dawson using 150m for his British list.

The next link in this small chain that takes in Prominence and Relative Height is Dominance, and therefore Dominance can be viewed as the next step in the evolutionary process of Prominence.

Dominance is a new concept for a published list to hills within Britain and to the knowledge of the author was first used for hills within Britain in early 2009 under the working title of ‘The Ultra Prominent Summits of Wales’, this title was shortened to the UPPs and was later changed to ‘The Dominant Hills of Wales.’  The change of name was instigated after a discussion with Mark Trengove who pointed out that the same concept of Dominance had been used by Eberhard Jurgalski in written format in 2001 and in published format in 2004, and as the 5,000ft prominence world peaks are known as the Ultras, their title having been shortened from the Ultra Prominent Peaks, it was sensible not to use a working title that was similar to another list that used different criteria.  Therefore, the title of Y Trechol - The Dominant Hills of Wales became the norm and the term of Dominance used to describe it, with the term Y Trechol being the Welsh for ‘The Dominants.’

The concept of Dominance was independently conceived by the author and was not copied from Eberhard as until discussing the concept of this list with Mark Trengove, I had not heard of Eberhard Jurgalski, but the term ‘Dominance’ follows Eberhard’s lead, as this is the norm when dealing with terms such as Prominence and Relative Height, each in turn were coined by someone and then they have become terms used by many.

To fulfil the qualification of a hill being Dominant its prominence has to be first known.  Therefore a Dominant list cannot be compiled unless the Prominence of each hill is known beforehand, and for a country such as Wales there are many hills that qualify under a stipulated minimum prominence of 30m.  I thought it wise to follow this minimum prominence figure as this had been previously used in a number of listings, these are briefly detailed below.

For Wales these 30m minimum prominence based lists were first published over a period of 20 years from 1984–2004.  These listings were reliant upon data produced by Terry Marsh, Michael Dewey and Myrddyn Phillips.  However, although all the lists produced by these people specified a minimum drop of 30m none of them listed the actual drop figure; this was added at a later date.  During this time listings to the majority of these hills were also independently produced by E. D. ‘Clem’ Clements whose work appeared on the RHB Yahoo Group database.

The theory of Dominance was conceptualized shortly after all the drop values were added to my hand written Master Lists and the 100m height bands expanded upward to include all P30 summits in Wales.  This Dominance criterion was conceptualized at approximately the same time as that of Remoteness, with both taking form from the same question – ‘what else can be considered once prominence values are given to all hills?’  Once this question was asked the theory of Dominance sprung in to my mind and that of Remoteness soon followed.

The Remoteness list was later published on Geoff Crowder’s v-g.me website in 2011, and updated and co-authored with Aled Williams and published by Europeaklist, Haroldstreet and Mapping Mountains in April 2015.  But until now the Dominance list has never been published.


Before detailing what Y Trechol - The Dominant Hills of Wales list consists of it may be prudent to detail the qualification for the main list:

Those P30 hills whose prominence equal or exceed half that of their absolute height.

Also included is a list to the Lesser Welsh Dominants, these are the additional P30 summits whose prominence is between one third and half that of their absolute height.



To access Y Trechol - The Dominant Hills of Wales 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; 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.  The names of the Groups used in this list have received extensive input from Aled Williams.

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. 78m) 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.

Dominance:  This is the Dominance of the hill’s height between bwlch and summit (its prominence) over that of its height from sea level (Ordnance Datum Newlyn) to its bwlch.  The Dominance is given as a percentage.

Region:  There are three Regions in Wales; North Wales, Mid and West Wales, and South Wales.  The Regional split of Wales used in this list has received extensive input from Aled Williams and will be detailed on the Mapping Mountains blog at a later date.

Sub-Region:  There are a number of Sub-Regions in Wales and those used in this list have received extensive input from Aled Williams and they will be detailed on the Mapping Mountains blog at a later date.

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.

Grid Reference Summit:  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) if 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.

Height (m) Summit:  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.

Grid Reference Bwlch:  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.

Drop (m) Summit to Bwlch:  This column details the prominence of the hill; this is commonly referred to as ‘drop’ or ‘reascent’.  The drop is the height difference between the summit and connecting bwlch to the higher parent peak 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.

Drop (m) – Bwlch to ODN:  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 Aled Williams and Mark Trengove for their continued support and to Eberhard Jurgalski for taking Dominance to the masses.  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.


This list will appear in monthly or bimonthly instalments with the seventeenth Group being the Tarennydd.  The Dominant Hills of Y Berwyn will appear on the 3rd February 2017.



To access Y Trechol - The Dominant Hills of Wales list please click {here}