Tuesday, 27 June 2017

Mapping Mountains – Hill Reclassifications – 100m Twmpau


100m Twmpau – Hill Reclassifications

The 100m Twmpau (thirty welsh metre prominences and upward) are the Welsh hills at or above 100m and below 20om in height that have a minimum drop of 30m.  Accompanying the main P30 list is a sub list entitled the 100m Sub-Twmpau with the qualification to this sub category being all Welsh hills at or above 100m and below 200m in height with 20m or more and below 30m of drop.

The list is authored by Myrddyn Phillips and the posts that have appeared on Mapping Mountains detailing the additions, reclassifications and deletions to the main P30 list and the sub list appear below presented chronologically in receding order.








Mapping Mountains - Hill Reclassifications - 100m Twmpau

Bryn y Llan or Highermost Gredington (SJ 453 383) - 100m Sub-Twmpau addition (7th reclassification)


There has been an addition to the listing of the 100m Twmpau (thirty welsh metre prominences and upward) due to analysis of the Ordnance Survey enlarged mapping on the Geograph website by Myrddyn Phillips and which has now been refined and confirmed by analysis of LIDAR data by Aled Williams.  With the criteria for the 100m Twmpau being all Welsh hills 100m or more and below 200m in height with 30m minimum drop.

Accompanying the Twmpau list is a sub list entitled the Sub-Twmpau.  With the criteria for 100m Sub-Twmpau qualification being all Welsh hills at or above 100m and below 200m in height with 20m or more and below 30m of drop, with this addition affecting this sub category of hill.

Prior to analysis of the Ordnance Survey enlarged mapping on the Geograph website and the subsequent analysis of LIDAR data the hill was not classified.  Analysis of the Ordnance Survey enlarged map gave the hill an estimated drop of c 23m based on the 114m summit spot height and an estimated bwlch height of c 91m, with these values being sufficient for the hill to be classified as a 100m Sub-Twmpau.

The hill is a part of the Maelor Saesneg group of hills, this part of Wales is the land to the east of the Afon Dyfrdwy (River Dee) and originated as a cantref of the Kingdom of Powys, with its Cardinal Hill being Pt. 157m (SJ 549 440) and is placed in the Region of North Wales (Region A, Sub-Region A4), and is situated with the small community of Hanmer to the north and Cumber’s Bank to the north north-west.

According to the map the summit of the hill is situated in mixed woodland and as it is not a part of open access land permission to visit the high point should be sought.  There is access toward the summit on public footpaths from the north originating from Hanmer that follows the eastern shore of Hanmer Mere, and from the south-west following the boundary of the woodland in its upper section.

The name of the hill is Bryn y Llan or Highermost Gredington and this was derived from the Tithe map by Aled Williams, and its addition to 100m Sub-Twmpau status is due to analysis of the Ordnance Survey enlarged mapping on the Geograph website by Myrddyn Phillips and confirmation of its status via LIDAR data analysed by Aled Williams.  LIDAR (Light Detection & Ranging) is highly accurate height data that is now freely available for much of England and Wales.

Aled’s analysis of LIDAR data gives the hill the following details:


Bryn y Llan or Highermost Gredington

Summit Height:  115.1m

Summit Grid Reference:  SJ 45301 38375

Bwlch Height:  91.0m

Bwlch Grid Reference:  SJ 51088 36435

Drop:  24.1m


Therefore, the 115.1m LIDAR data produced for the summit position at SJ 45301 38375 and the 91.0m LIDAR data produced for the bwlch position at SJ 51088 36435 gives this hill 24.1m of drop, which is sufficient for its inclusion as a 100m Sub-Twmpau, therefore this hill is included in this sub category and the total in the Twmpau will be updated accordingly.


The full details for the hill are:

Cardinal Hill:  Pt. 157m (SJ 549 440)

Summit Height:  115.1m (LIDAR data)

Name:  Bryn y Llan or Highermost Gredington

OS 1:50,000 map:  126

Summit Grid Reference:  SJ 45301 38375 
  
Drop:  24.1m (LIDAR data)



My thanks to Aled Williams for sending the details of this hill to me.

Myrddyn Phillips (April 2017)






Mapping Mountains - Hill Reclassifications - 100m Twmpau

Pandy Bank (SJ 336 538) - 100m Twmpau addition (6th reclassification)

Survey post for Pandy Bank

Significant Name Changes post for Pandy Bank


There has been an addition to the 100m Twmpau (thirty welsh metre prominences and upward) hill list instigated by a survey with the Trimble GeoXH 6000.   The hill is situated on the northern outskirts of Wrecsam (Wrexham) overlooking the community of Pandy, in the easterly part of the Moel y Gamelin range of hills.

The Trimble GeoXH 6000 survey that resulted in this hill’s inclusion as a 100m Twmpau was conducted in the afternoon on the 5th April 2016 in good, dry and sometimes bright conditions.

The hill can be accessed from its north from the end of the Pont y Capel Lane where there is sufficient space for three or four cars to be parked.  A broad path leaves the end of the paved road beside a low metal barrier barring entrance to four wheel drive vehicles; a sign proclaims that the land beyond this point is private, so those wishing to visit should technically seek permission to do so.  The broad path leads through woodland toward a high metal fence that borders the adjacent Shrewsbury – Chester railway line where the bwlch of the hill is situated.  The broad path follows this boundary and the summit can be accessed up its steep northern face or from its south, all approaches are steep and much of the hill’s upper slopes have silver birch covering them.

The hill is named Pandy Bank and its summit is positioned at SJ 336 538.  This is a locally known name for the hill and was found when I made enquiries during my ascent.  The only name that appears on current Ordnance Survey maps relating to this hill is ‘Spoil Heap (disused)’.  As the Ordnance Survey detail implies, this hill is the relic of mining waste which was deposited from the old Gresford Colliery.  This site now forms a part of the Gresford Industrial Park.

Current Ordnance Survey 1:50,000 and 1:25,000 mapping does not give this hill any ring contours; however the Ordnance Survey enlarged mapping hosted on the Geograph website does, and uses contour intervals of 5m, with an uppermost contour ring of 105m and bwlch contouring between 70m – 75m.  These contours give the hill a minimum of 30m of drop and contour interpolation prior to the survey with the Trimble suggested that the hill had 34m – 35m of drop. 

The survey with the Trimble GeoXH 6000 resulted in a 105.4m (converted to OSGM15) summit height and with the bwlch estimated to be 71m high; these values give the hill c 34m of drop.


The full details for the hill are:

Cardinal Hill:  Moel y Gamelin

Summit Height:  105.4m (converted to OSGM15)

Name:  Pandy Bank

OS 1:50,000 map:  117

Summit Grid Reference:  SJ 33630 53882

Drop:  c 34m


Pandy Bank (SJ 336 538) the new 100m Twmpau

For details on the survey that resulted in this hill being included as a 100m Twmpau please click {here}

Myrddyn Phillips (April 2016)







Mapping Mountains - Hill Reclassifications - 100m Twmpau

Pentre Clawdd Gorse (SJ 311 442) - 100m Twmpau addition (5th reclassification)

Summit survey post and bwlch survey post for Pentre Clawdd Gorse

Summit Relocations post for Pentre Clawdd Gorse
  

There has been an addition to the 100m Twmpau (thirty welsh metre prominences and upward) hill list instigated by a survey with the Trimble.   The hill is situated just to the east of the A 483 and to the north-east of Rhiwabon (Ruabon) in the eastern part of the Moel y Gamelin range of hills.

The Trimble GeoXH 6000 survey that resulted in this hill’s addition to the 100m Twmpau list was conducted in the afternoon of the 23th February 2016 on a beautiful winter’s day in good, dry and sunny conditions.

The hill is named Pentre Clawdd Gorse and access to it is relatively easy as its summit is positioned on Wat’s Dyke, this ancient earthwork stretches from the Dee estuary in the north to Shropshire in the south, and public footpaths follow its course over this hill.

Pentre Clawdd Gorse is adjoined to the summit of Wynnstay Park which is an approximate one kilometre due south from it and which has a 141m spot height given it on current Ordnance Survey maps.  The summit of Wynnstay Park was surveyed on the 20th October 2015 resulting in a summit height of 141.2m (converted to OSGM15).  On the same day the bwlch positioned at SJ 307 437 was also surveyed resulting in a bwlch height of 111.7m (converted to OSGM15).  If this was the critical bwlch for Wynnstay Park the hill just failed to make it to P30 Twmpau status with only 29.5m of drop.  However, further map inspection showed that the summit area of Pentre Clawdd Gorse had two 140m small ring contours on it, and if one proved to be at least 0.5m higher than the summit of Wynnstay Park the bwlch positioned at SJ 307 437 would be adjoined to Pentre Clawdd Gorse and the hill would be a new P30.

The survey with the Trimble GeoXH 6000 resulted in a summit height of 142.0m (converted to OSGM15), and therefore as Pentre Clawdd Gorse is 0.8m higher than Wynnstay Park the 111.7m (converted to OSGM15) high bwlch positioned at SJ 307 437 is that for the higher hill. 


The full details for the hill are:

Cardinal Hill:  Moel y Gamelin

Summit Height:  142.0m (converted to OSGM15)

Name:  Pentre Clawdd Gorse

OS 1:50,000 map:  117

Summit Grid Reference:  SJ 311 442

Drop:  30.3m (converted to OSGM15)


The summit of Pentre Clawdd Gorse (SJ 311 442) the new addition to the 100m Twmpau list

For details on the survey that resulted in this hill being added to the 100m Twmpau list please click {here} for summit and {here} for the bwlch survey.

Myrddyn Phillips (February 2016)







Mapping Mountains - Hill Reclassifications - 100m Twmpau

The Pimple (SJ 299 472) - 100m Sub-Twmpau addition (4th reclassification)

Survey post for The Pimple

Significant Height Revisions post for The Pimple

Significant Name Changes post for The Pimple

Summit Relocations post for The Pimple


There has been an addition to the Sub category within the 100m Twmpau (thirty welsh metre prominences and upward) hill list instigated by a survey with the Trimble GeoXH 6000.   The hill is situated next to the small community of Pentre Bychan which is adjacent to Rhosllanerchrugog, in the easterly part of the Bryniau Clwyd.

These details are retrospective as the Trimble GeoXH 6000 survey that resulted in this hill’s inclusion as a 100m Sub- Twmpau was conducted on the 20th October 2015 on a beautiful autumnal day in good, dry and sunny conditions.

The hill can be accessed from its west where a public footpath traverses the course of the valley where its bwlch is positioned.  However, permission should be sought for those wishing to visit as the summit is not on open access land.  When I visited I asked permission to do so and was kindly directed to the best ascent route.

The hill is named The Pimple and its summit is positioned at SJ 299 472.  This is a locally known name for the hill and was found when I made enquiries during a number of data sets taken at the area of the bwlch.  The hill remains unnamed on current Ordnance Survey maps and its locally known name relates directly to the past industrial heritage of the hill, as its summit is made of mining waste that is now stabilised and grassed over.  The uppermost part of the summit is relatively small in area and squat, and looks like a pimple as it sits upon another elevated part of the hill.

Current mapping does not give this hill any summit ring contours, although the adjacent field does have a 154m map spot height on it, both of these points were surveyed with the summit known as The Pimple being 0.4m higher according to the Trimble data.

The survey with the Trimble GeoXH 6000 resulted in a 153.5m (converted to OSGM15) summit height and a 128.3m (converted to OSGM15) bwlch height, giving this hill 25.2m of drop and confirming its entry in to the 100m Sub-Twmpau ranks.


The full details for the hill are:

Cardinal Hill:  Moel y Gamelin

Summit Height:  153.5m (converted to OSGM15)

Name:  The Pimple

OS 1:50,000 map:  117

Summit Grid Reference:  SJ 29984 47262

Drop:  25.2m (converted to OSGM15)


Gathering data at the summit of The Pimple, which resulted in this hill's confirmation as a 100m Sub-Twmpau

For details on the survey that resulted in this hill being included as a 100m Sub-Twmpau please click {here}


Myrddyn Phillips (October 2015)







Mapping Mountains - Hill Reclassifications - 100m Twmpau

Bersham Bank (SJ 311 481) - 100m Twmpau addition (3rd reclassification)

Survey post for Bersham Bank

Significant Height Revisions post for Bersham Bank

Significant Name Changes post for Bersham Bank
  

There has been an addition to the 100m Twmpau (thirty welsh metre prominences and upward) hill list instigated by a survey with the Trimble GeoXH 6000.   The hill is situated on the southern outskirts of Rhostyllen, which is a south-western suburb of Wrecsam (Wrexham), in the easterly part of the Bryniau Clwyd.

These details are retrospective as the Trimble GeoXH 6000 survey that resulted in this hill’s inclusion as a 100m Twmpau was conducted on the 13th October 2015 in good, dry and sometimes bright conditions, in the afternoon of an early autumnal day.

The hill can be accessed from its east from a road adjacent to an industrial estate.  Beside the road is a perimeter fence seemingly barring entrance to a path on the lower slopes of the hill, however, one section of the six foot high fence has been toppled over giving access to the public, including local people, who I was told occasionally walk up the hill.

The hill is named Bersham Bank and its summit is positioned at SJ 311 481.  This is the preferred locally known name for the hill and was found when I made enquiries after my ascent.  The only name that appears on current Ordnance Survey maps relating to this hill is ‘Colliery (disused)’.  As the Ordnance Survey detail implies, this hill is the relic of coal waste which was deposited from the workings of the Bersham Colliery which closed its operations in December 1986.

Current mapping does not give this hill any ring contours, although other hills created from coal waste that are relatively near to Bersham Bank at SJ 311 469 and SJ 300 473 do possess separate ring contours.  Although current maps do not give this hill any summit contours, the ones at its bwlch are between 100m – 105m, with the height of the bwlch estimated as being c 103m.
The survey with the Trimble GeoXH 6000 resulted in a 153.6m (converted to OSGM15) summit height and with the bwlch estimated to be c 103m high; these values give the hill c 51m of drop.


The full details for the hill are:

Cardinal Hill:  Moel y Gamelin

Summit Height:  153.6m (converted to OSGM15)

Name:  Bersham Bank

OS 1:50,000 map:  117

Summit Grid Reference:  SJ 31159 48116

Drop:  c 51m


Bersham Bank (SJ 311 481) is now confirmed as a 100m Twmpau

For details on the survey that resulted in this hill being added to the list of 100m Twmpau hills please click {here}

Myrddyn Phillips (October 2015)






Mapping Mountains - Hill Reclassifications - 100m Twmpau

Castell Dinbych (SJ 051 657) - 100m Sub-Twmpau reclassified to 100m Twmpau (2nd reclassification)

Survey post for Castell Dinbych


There has been a reclassification to the Twmpau list with a 100m Sub-Twmpau being reclassified to a 100 Twmpau due to a survey with the Trimble GeoXH 6000.  The hill is situated in the centre of Dinbych (Denbigh) in north-east Wales, and its name is Castell Dinbych (Denbigh Castle in English).  

The present construct is the remains of one of Edward 1’s fortifications after he visited his neighbours and asked them not to be so rebellious.  It is situated in an impressive position overlooking the town to the west and the Vale of Clwyd to the east.  In its time the castle must have been an imposing construction, one no doubt meant to subjugate.  

The critical bwlch of the hill may be placed in someone’s living room beside a road named Bryn Stanley; I asked permission to place the Trimble on a fence post adjacent to a front garden as satellite reception may have been awkward inside the bungalow.


The full details for the hill are:

Cardinal Hill:  Mwdwl Eithin

Summit Height:  143.2m (converted to OSGM15)

Name:  Castell Dinbych

OS 1:50,000 map:  116

Summit Grid Reference:  SJ 051 657

Drop:  33.0m (converted to OSGM15)


Castell Dinbych (SJ 051 657) is now reclassified to a 100m Twmpau

For details on the survey that confirmed this hill's 100m Twmpau status please click {here}


Myrddyn Phillips (August 2014)






Mapping Mountains - Hill Reclassifications - 100m Twmpau

Bryn y Beili (SJ 235 643) - 100m Twmpau addition (1st reclassification)

Survey post for Bryn y Beili

Significant Height Revisions post for Bryn y Beili


There has been a new addition to the Welsh 100m P30 list due to a recent survey with the Trimble GeoXH 6000.  The hill is situated in the centre of Yr Wyddgrug (Mold) in north-east Wales.  The name of the hill is Bryn y Beili (Bailey Hill in English), and it is almost hidden from view when approaching from the High Street as it rises behind the former Pendref Chapel and is surrounded by a high wall, trees and shrubs.  

Bryn y Beili has the remains of a Norman castle on its summit which may have been built on a much earlier burial mound.  This hill lends its name to the current usage of Yr Wyddgrug and Mold as the name of the town; yrgŵyddcrug (high hillthe prominent mound) in Cymraeg, and monthault in Norman French.  

The hill was proposed by Mark Trengove as a potential new P30 and involved an exciting survey as the Trimble GeoXH 6000 was run over by a car whilst surveying in the area of the bwlch.  Our second survey attained a good data set from the tree covered summit and was backed up with a basic levelling survey from the position of a spot height just below the summit.


The full details for the hill are:

Cardinal Hill:  Moel y Gamelin

Summit Height:  143.0m (converted to OSGM15)

Name:  Bryn y Beili

OS 1:50,000 map:  117

Summit Grid Reference:  SJ 235 643

Drop:  31.5m (converted to OSGM15)


Bryn y Beili (SJ 235 643), the new 100m Twmpau
For details on the survey that promoted this hill to 100m Twmpau status please click {here}


Myrddyn Phillips (May 2014)

Monday, 26 June 2017

Mapping Mountains – Hill Reclassifications – 200m Twmpau


200m Twmpau – Hill Reclassifications

The 200m Twmpau (thirty welsh metre prominences and upward) are the Welsh hills at or above 200m and below 30om in height that have a minimum drop of 30m.  Accompanying the main P30 list is a sub list entitled the 200m Sub-Twmpau with the qualification to this sub category being all Welsh hills at or above 200m and below 300m in height with 20m or more and below 30m of drop.

The list is authored by Myrddyn Phillips and the posts that have appeared on Mapping Mountains detailing the additions, reclassifications and deletions to the main P30 list and the sub list appear below presented chronologically in receding order.









Mapping Mountains - Hill Reclassifications - 200m Twmpau

Pen y Gaer (SO 139 976) – 200m Twmpau reclassified to Trichant (7th reclassification)

Survey post for Pen y Gaer


There has been a reclassification of a 200m Twmpau (thirty welsh metre prominences and upward) to the listing of Y Trichant due to surveying with the Trimble GeoXH 6000.

The details relating to this hill’s inclusion in the listing of Y Trichant are retrospective as the survey with the Trimble took place on the 11th January 2015 and the Hill Reclassifications post for its 300m Twmpau status was published on Mapping Mountains on the 12th January 2015.

The criteria for 200m Twmpau status is all Welsh hills at or above 200m and below 300m in height with 30m minimum drop, whilst Y Trichant is the title for the hills in the 300m height band of the Twmpau and takes in all Welsh hills at or above 300m and below 400m in height with 30m minimum drop, with the introduction to the re-naming of this list appearing on Mapping Mountains on the 13th May 2017.

Prior to the survey with the Trimble GeoXH 6000 the hill was listed with 87m of drop based on the 299m summit spot height that appears on the Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer map and the 212m bwlch spot height that appears on the Ordnance Survey enlarged mapping hosted on the Geograph website.

The hill is situated in the Carnedd Wen range with its Cardinal Hill being Stingwern Hill (SJ 132 014and is placed in the North Wales Region (Region A, Sub-Region A4), and is positioned with the small community of Bettws Cedewain to the west south-west and Aber-miwl (Abermule) to the south-east.

As the summit of the hill is not a part of designated open access land permission to visit its high point should be sought.  For those seeking this and wishing to visit there is a public footpath just to the north of the summit which can be accessed from either the north-east or the south-west.

The name of the hill is Pen y Gaer and it is only the third hill that I know of whose status has been altered due to the Ordnance Survey remodelling known as OSGM15.  This remodelling has increased the accurately known height of hills in Wales by approximately 2-4cm, and the other two hills whose status was altered because of OSGM15 are Calf Top (SD 664 856) and Carn Ysgubor (SM 699 246).


Surveyed height of Pen y Gaer pre OSGM15 = 299.974m

Surveyed height of Pen y Gaer post OSGM15 = 300.002m



The full details for the hill are:

Cardinal Hill:  Stingwern Hill

Summit Height:  300.0m (converted to OSGM15)

Name:  Pen y Gaer

OS 1:50,000 map:  136

Summit Grid Reference:  SO 13997 97677

Drop:  88m



Pen y Gaer (SO 139 976) reclassified from a 200m Twmpau to a Trichant



Myrddyn Phillips (June 2017)






Mapping Mountains - Hill Reclassifications - 200m Twmpau

Moelfryn (SH 569 511) – 200m Twmpau reclassified to 200m Sub-Twmpau (6th reclassification)


There has been a reclassification to the listing of Twmpau (thirty welsh metre prominences and upward) hills due to analysis of LIDAR data by Aled Williams.  The hill was listed in the 200m height band of P30 Twmpau hills and it has now been reclassified to a 200m Sub-Twmpau, with the criteria for 200m Twmpau status being all Welsh hills at or above 200m and below 300m in height with 30m minimum drop, and the 200m Sub-Twmpau being all Welsh hills at or above 200m and below 300m in height with 20m or more and below 30m of drop.

The hill was originally listed in the sub list that accompanied the P30 lists when published on Geoff Crowder’s v-g.me website under the title of ‘Hills to be surveyed.’  When this list was re-evaluated the hill was reclassified to a P30 with c 30m of drop based on its 277m summit spot height that appears on the Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer maps and an estimated bwlch height of c 247m.  However, the 277m spot height may be erroneous as this summit is immersed in conifer plantation and the only spot height preceding it that has appeared on Ordnance Survey maps is the imperial height of 901ft (274.6m) which originated on the Six-Inch series.  Therefore there seems no evidence to support how a spot height has changed by 2.4m when the summit is unsighted and blanketed in trees.

The hill is situated in the north-eastern part of the Beddgelert Forest and is adjoined to Crib Nantlle and the Moel Hebog group of hills, with its Cardinal Hill being Pt. 734m (SH 525 502) and is placed in the Region of North Wales (Region A, Sub-Region A1), and is situated between the small communities of Rhyd-ddu to its north and Beddgelert to its south south-east.

As the hill is immersed in conifer plantation any ascent may prove problematical, but forest tracks are marked on the map to the north-east and south-west of the summit, with the former indicated as giving nearer access.

The name of the hill is Moelfryn and its reclassification to a 200m Sub-Twmpau is due to the analysis of LIDAR data by Aled Williams.  LIDAR (Light Detection & Ranging) is highly accurate height data that is now freely available for much of England and Wales.

Aled’s analysis of LIDAR data gives the hill the following details:


Moelfryn

Summit Height:  269.0m

Summit Grid Reference:  SH 56900 51151

Bwlch Height:  246.1m

Bwlch Grid Reference:  SH 56416 51301

Drop:  22.9m


Therefore, the 269.0m LIDAR data produced for the summit position at SH 56900 51151 and the 246.1m LIDAR data produced for the bwlch position at SH 56416 51301 gives this hill 22.9m of drop.  However as the DTM model may have struggled to model the summit hillock the detail from the Ordnance Survey Six-Inch map is being taken for the summit.


The full details for the hill are:


Cardinal Hill:  Pt. 734m (SH 525 502)

Summit Height:  275m (height rounded up from Six-Inch map)

Name:  Moelfryn

OS 1:50,000 map:  115

Summit Grid Reference:  SH 56900 51151  

Drop:  29m (summit height from Six-Inch map and bwlch height from LIDAR data)



My thanks to Aled Williams for sending the details of this hill to me.

Myrddyn Phillips (May 2017)







Mapping Mountains - Hill Reclassifications - 200m Twmpau


Mynydd y Drum (SN 807 097) - 200m Twmpau reclassified to 200m Sub-Twmpau (5th reclassification)

Survey post for Mynydd y Drum


There has been a reclassification to the listing of Twmpau (thirty welsh metre prominences and upward) hills due to analysis of LIDAR data by Kevin McGovern and also independently by Aled Williams, and subsequently confirmed via a survey with the Trimble GeoXH 6000.  The hill has been reclassified from a 200m Twmpau to a 200m Sub-Twmpau, with the criteria for the former being all hills in Wales at or above 200m and below 300m in height that have a minimum drop of 30m, and the criteria for the sub category being all hills in Wales at or above 200m and below 300m in height with 20m or more and below 30m of drop.

The hill had been listed with an estimated drop of c 53m based on an estimated bwlch height of c 244m and the 297m summit height positioned at SN 807 098 derived from the spot height that appears on the Ordnance Survey 1:25,000 Explorer map numbers 12 and 165, whilst the Ordnance Survey 1:50,000 Landranger map number 160 gives a 298m summit spot height at the same position.  This latter spot height is derived from the 978.1ft (298.1ft) height on the Ordnance Survey old Six-Inch map.

When this hill was originally listed in the Welsh P30 lists on the v-g.me website it had an accompanying note which stated ‘3 points of 300m on 1985 map may probably no longer exist (quarrying)’.  The hand written Master List stated ‘Due to opencast workings the three points of 300c at GR 830 112 on 1985 1:50,000 map probably no longer exist’.  These three points are in the vicinity of where a 984ft (299.9m) height appears on the Ordnance Survey old Six Inch map and in all likelihood signified where the summit of this hill was once positioned.  Since this time the opencast workings which take in the northern and eastern part of the larger hill known as Mynydd y Drum have destroyed the old 984ft (299.9m) summit, but in its place are two separate hills comprising the spoil from the mine workings, with this Hill Reclassifications post concentrating on the remaining ‘natural’ and now lower of these three summits. 

Prior to analysis of LIDAR data Mynydd y Drum was listed with one summit, but due to opencast mining a further two summits have been created which are artificial and comprise the remains of waste spoil, the hill which this Hill Reclassifications post details is the remaining ‘natural’ summit, which is now lower in height compared to the two artificial summits, this has resulted in new bylchau heights and positions and also drop values for these three hills, all of these will be detailed in this and the two previous Hill Reclassifications posts, with the other two hills being Teisen Priodas (SN 820 108) and MRF Tip (SN 828 114).

The hill is adjoined to the Fforest Fawr group with its Cardinal Hill being Fan Gyhirych (SN 880 191) and is placed in the Region of South Wales (Region C, Sub-Region C2), and is positioned between the small town of Ystradgynlais to the north-west and the village of Blaendulais (Seven Sisters) to the south-east.

The upper part of the hill is situated within open access land and can be easily accessed from a number of public footpaths that emanate from Cwm Tawe (Swansea Valley) to the north-west and from Cwm Dulais (Dulais valley) from the south-east.

The name of the hill is Mynydd y Drum and its reclassification to a 200m Sub-Twmpau is due to the analysis of LIDAR data by Kevin McGovern and also independently by Aled Williams.  LIDAR (Light Detection & Ranging) is highly accurate height data that is now freely available for much of England and Wales.

Kevin’s analysis of LIDAR data gives the hill the following details:


Mynydd y Drum

Summit Height:  296.1m (converted to OSGM15)

Summit Grid Reference:  SN 80720 09754

Bwlch Height:  271.8m (converted to OSGM15)

Bwlch Grid Reference:  SN 81526 10520

Drop:  24.3m


Therefore, the 296.1m LIDAR data produced for the summit position at SN 80720 09754 and the 271.8m LIDAR data produced for the bwlch position at SN 81526 10520 is sufficient for this hill to be reclassified from a 200m Twmpau to a 200m Sub-Twmpau with 24.3m of drop, with the details from the Trimble GeoXH 6000 survey being 296.2m (converted to OSGM15) summit at SN 80718 09753 and 271.4m bwlch (converted to OSGM15) at SN 81526 10519), giving this hill 24.8m of drop.

This now revises the total in the 200m Twmpau and the list will be updated accordingly.


The full details for the hill are:

Cardinal Hill:  Fan Gyhirych

Summit Height:  296.2m (converted to OSGM15, Trimble data)

Name:  Mynydd y Drum

OS 1:50,000 map:  160

Summit Grid Reference:  SN 80718 09753 
  
Drop:  24.8m (converted to OSGM15, Trimble data)


Mynydd y Drum (SN 807 097) now reclassified to a 200m Sub-Twmpau

My thanks to Mark Jackson for bringing the details of this hill to my attention, and to Kevin McGovern and Aled Williams for their analysis of LIDAR data.


Myrddyn Phillips (March 2017)







Mapping Mountains - Hill Reclassifications - 200m Twmpau

Y Ceiliog Mawr (SH 594 598) - 200m Twmpau addition (4th reclassification)


There has been a new addition to the 200m Twmpau (thirty welsh metre prominences and upward) hill list instigated through analysis of LIDAR data by Aled Williams.  The hill is one that Aled first proposed as a prospective P30 Twmpau approximately two years ago and it then waited to be Trimbled, but as it looked a daunting prospect the Trimble surveyor shied away from his duties, and in the meantime as LIDAR data is proving highly accurate I am using the data that Aled has obtained.

The hill is situated in the Glyderau group of hills with its Cardinal Hill being Y Garn (SH 630 595) and is placed in the Region of North Wales (Region A, Sub-Region A1).  The hill is positioned above Llyn Peris which is to its south and the small community of Nant Peris to its south-east and the town of Llanberis to its west.  The hill is a part of the old Dinorwig Slate Quarries, and can be accessed from tracks leading into the hill from the south-east and from the west.

The hill is known locally as Y Ceiliog Mawr which translates into English as the big cockerel.  I am thankful to Eric Jones for the information relating to this name and the history of the hill which comes from the following two passages on the Geograph website:


The Ceiliog Mawr is an igneous intrusion within the Dinorwig Quarries.  Several attempts were made to remove the intrusion but a considerable section of it remains.  "Ceiliog Mawr" means big cockerel.

Buildings associated with the Dinorwig HEP station have been built around the foot of a slightly modified 'cockerel'.  Three attempts were made in the past to 'slaughter the cockerel'.  In 1896 Mr Brinckman, the general manager, decided that the days of the cockerel were numbered.  On the day, the quarrymen were invited to witness what "a real explosion was like".  The cream of the Welsh aristocracy, and dozens of cameramen, were also invited to watch the demise of the cockerel.  The fateful moment came and the button pressed on the battery firer (the only occasion in the history of the quarry for a battery firer to be used).  A huge pall of smoke emerged from the rock.  When it cleared, Y Ceiliog Mawr stood unscathed.  A visit by the Prince and Princess of Wales in May 1902 was an excuse for another go, this time using two tons of explosive, only to leave more egg on the managers' face.  Finally, in 1905, 10 shafts were dug into the outcrop at a cost of £437-12-2 and explosives set at the bottom of each.  Again, only a few loose rocks were dislodged.  Ever since, the Ceiliog Mawr has been an icon of Dinorwig Quarry.


Current Ordnance Survey 1:50,000 and 1:25,000 mapping does not give this hill any ring contours, as is the norm for areas of land that have been quarried.  The hill is of interest (and quite daunting) as it is only now listed as a 200m Twmpau through the quarrying activities of past years, as it has been left as a stone monolith separated from its connecting bwlch by over 37m of vertical height.


Aled’s analysis of LIDAR data gives the hill the following details:


Y Ceiliog Mawr

Summit Height:  220.3m

Summit Grid Reference:  SH 59467 59848

Bwlch Height:  182.8m

Bwlch Grid Reference:  SH 59538 59823

Drop:  37.5m


Therefore, the 220.3m LIDAR data produced for the summit position at SH 59467 59848, and the 182.8m LIDAR data produced for the bwlch position at SH 59538 59823 is sufficient for this hill to be included in the list of 200m Twmpau hills with 37.5m of drop, and therefore Y Ceiliog Mawr is included in the listing of Twmpau which will be updated accordingly.


The full details for the hill are:


Cardinal Hill:  Y Garn

Summit Height:  220.3m (LIDAR data)

Name:  Y Ceiliog Mawr

OS 1:50,000 map:  115

Summit Grid Reference:  SH 59467 59848

Drop:  37.5m (LIDAR data)



My thanks to Aled for supplying the details of his LIDAR analysis of this hill.

Y Ceiliog Mawr - the new 200m Twmpau.  Photo © Aled Williams

To view an old and a relatively recent photograph of Y Ceiliog Mawr {here} {here}


Myrddyn Phillips (December 2016)






Mapping Mountains - Hill Reclassifications - 200m Twmpau

Gallt y Celyn (SH 811 542) - 200m Sub-Twmpau reclassified to 200m Twmpau (3rd reclassification)

Summit survey post for Gallt y Celyn

Bwlch survey post for Gallt y Celyn

Significant Name Changes post for Gallt y Celyn


There has been a reclassification within the 200m Twmpau (thirty welsh metre prominences and upward) hill list instigated by a survey with the Trimble GeoXH 6000.   The hill has a convoluted history of reclassification and is situated just to the north of the A 5 and southward of the small community of Capel Garmon and south-eastward of the town of Betws-y-coed, and is positioned in the Mynydd Hiraethog range of hills.

The Trimble GeoXH 6000 survey that resulted in this hill’s reclassification from a 200m Sub-Twmpau to a 200m Twmpau was conducted in the afternoon of the 23th February 2016 on a beautiful winter’s day in good, dry and sunny conditions.

The hill is unnamed on current Ordnance Survey maps but is given as a part of Gallt y Celyn on the Tithe map and therefore this name is deemed appropriate to use.
Access to the hill is relatively easy as there is a public footpath approaching from the north which can be accessed from Capel Garmon, and also one from the south-east which can be accessed from a steep minor lane that heads north from the A 5.  The summit of the hill is only a short distance from where these footpaths meet and is on open access land.

The hill has a convoluted history of inclusion and exclusion from the 200m P30 Welsh list as it was originally included in the ‘Hills to Survey’ Sub-List that accompanied the main P30 lists on Geoff Crowder’s v-g.me website.  This Sub-List was reliant upon the details on Ordnance Survey maps being correct and did not take in contour interpolation for inclusion within the main P30 list.  After the Sub-List was standardised and contour interpolation used, the hill was reclassified to a P30 with c 30m of drop, based on a 258m summit spot height and an estimated bwlch height of c 238m.  To complicate matters this hill had twin tops, both given a 258m spot height on Ordnance Survey maps, these tops were surveyed with the Trimble on the 24th December 2013 with the following results:


257.610m (converted to OSGM15) at SH 81121 54259.

257.093m (converted to OSGM15) at SH 81007 54476.


Although the twin tops had been separated the bwlch was not surveyed and as it was estimated to be c 238m high, the drop for this hill was accepted as being just under the qualifying minimum drop of 30m and therefore the hill re-joined the ranks of Subs.

It was always my intention to survey the bwlch and determine once and for all the classification of the hill, and on the 23rd February I found myself immersed in a water laden bog gathering the allotted five minutes of data.  This survey resulted in a bwlch height of 227.5m (227.529m, converted to OSGM15), which gave this hill 30.1m (30.081m) of drop, and therefore it re-joins the ranks of P30 Twmpau hills.


The full details for the hill are:

Cardinal Hill:  Mwdwl Eithin

Summit Height:  257.6m (converted to OSGM15)

Name:  Gallt y Celyn

OS 1:50,000 map:  116

Summit Grid Reference:  SH 811 542

Drop:  30.1m (converted to OSGM15)


Gallt y Celyn (SH 811 542) in the centre foreground of this photograph and which has now been re-instated as a 200m P30 Twmpau.  Photograph taken from the summit of Dinas Mawr (SH 808 539)

For details on the survey that resulted in this hill being reclassified from a 200m Sub-Twmpau to a 200m Twmpau please click {here} for summit and {here} for the bwlch survey.

Myrddyn Phillips (February 2016)







Mapping Mountains - Hill Reclassifications - 200m Twmpau

Bwlch Clump (SJ 170 108) - 200m Twmpau reclassified to 200m Sub-Twmpau (2nd reclassification)

Survey post for Bwlch Clump

Summit Relocations post for Bwlch Clump

Significant Name Changes post for Bwlch Clump


There has been a reclassification within the 200m Twmpau (thirty welsh metre prominences and upward) hill list instigated by a survey with the Trimble GeoXH 6000.   The hill has twin map heighted summits and is situated to the south-east of Dyffryn Meifod and to the north-west of the Maesmawr valley and forms part of the Carnedd Wen range of hills.

These details are retrospective, as the Trimble GeoXH 6000 survey that resulted in this hill’s reclassification from a P30 Twmpau hill to a 200m Sub- Twmpau hill was conducted in the afternoon of the 20th January 2016 on a beautiful crisp winter day in good, dry and sunny conditions.

The lower section of the hill can be accessed from public footpaths to its west and east.  However, its summit does not appear on open access ground, therefore permission to visit the high point should be sought.

The hill was originally included in the main 200m P30 list that appeared on Geoff Crowder’s v-g.me website as a single summit under the current 1:25,000 Explorer map height of 262m (SJ 173 109), and listed under the partly invented name of Pen y Bryn Wood (Bryn Wood being the name of the wood to the north-east of the originally listed hill’s summit).  The hill gained a twin summit when the Ordnance Survey enlarged map on the Geograph website included a 262m spot height for the adjacent hill at SJ 170 108, which was named as Bwlch Clump on this map.  According to map contours the drop between each was not sufficient for both to be included as P30s, with interpolation suggesting c 19m of drop.

Therefore the purpose of this survey was to ascertain which of the two summits is higher and separate their twin top status, and see if the drop between each was sufficient for the lower Trimbled summit to be included as a Sub-Twmpau and ascertain if the higher summit retained its P30 status, as the listed drop value for this hill was c 30m, which was based on bwlch contour interpolation.


The survey results for this once twin topped P30 are:


Pt . 262.8m (originally listed as Pen y Bryn Wood)

262.8m (converted to OSGM15) summit at SJ 17354 10914

243.5m (converted to OSGM15) bwlch at SJ 17190 10797

19.4m drop



Bwlch Clump

263.9m (converted to OSGM15) summit at SJ 17063 10813

234.9m (converted to OSGM15) bwlch at SJ 17089 10581

29.1m drop


Therefore the survey with the Trimble GeoXH 6000 confirms that Bwlch Clump is 1.1m higher than Pt. 262.8m, and that Pt. 262.8m has 19.4m of drop and is not listed as a Sub-Twmpau, and that Bwlch Clump has 29.1m of drop and is therefore reclassified to a 200m Sub-Twmpau.


The full details for the new status of this hill are:


Cardinal Hill:  Carnedd Wen

Summit Height:  263.9m (converted to OSGM15)

Name:  Bwlch Clump

OS 1:50,000 map:  125

Summit Grid Reference:  SJ 17063 10813

Drop:  29.1m (converted to OSGM15)


Pt. 262.8m - now reclassified from a twin topped P30 to a non Sub-Twmpau.  How the mighty fall!!!

Bwlch Clump - now reclassified from a twin topped P30 to a 200m Sub-Twmpau

For details on the survey that resulted in this hill being reclassified from a 200m Twmpau to a 200m Sub-Twmpau please click {here}


Myrddyn Phillips (January 2016)







Mapping Mountains - Hill Reclassifications - 200m Twmpau

Broniarth (SJ 166 120) - 200m Sub-Twmpau addition (1st reclassification)

Survey post for Broniarth


There has been a confirmation of a new addition to the Sub category within the 200m Twmpau (thirty welsh metre prominences and upward) hill list instigated by a survey with the Trimble GeoXH 6000.   The hill is situated between the small community of Meifod to its north-west and that of Maesmawr to its south-east and is part of the Carnedd Wen range of hills.

These details are retrospective, as the Trimble GeoXH 6000 survey that resulted in this hill’s confirmation as a 200m Sub- Twmpau was conducted on the 20th January 2016 on a beautiful crisp winter day in good, dry and sunny conditions.

The hill can be easily accessed from its south where a narrow lane crosses from south-west to north-east across its southerly flank.  This would be a short visit of no more than a few minutes, so combining the hill with some of its neighbours is recommended.  However, permission should be sought for those wishing to visit as the summit is not on open access land.

The hill is unnamed on current Ordnance Survey 1:25,000 Explorer maps but is part of land known locally as Broniarth and which appears on some Ordnance Survey maps as an extended name of either Broniarth or Broniarth Hill.

This is a confirmation of this hill’s addition to the 200m Sub-Twmpau ranks as current Ordnance Survey enlarged mapping on the Geograph website has a 247m spot height on this hill’s bwlch, with the summit having a 268m spot height on the Ordnance Survey 1:25,000 Explorer map and the enlarged map hosted on the Geograph website.  These values give the hill 21m of drop, which compares favourably with the Trimble survey of 21.5m of drop.

The survey with the Trimble GeoXH 6000 resulted in a 267.9m (converted to OSGM15) summit height and a 246.5m (converted to OSGM15) bwlch height, giving this hill 21.5m of drop and confirming its entry in to the 200m Sub-Twmpau ranks.


The full details for the hill are:

Cardinal Hill:  Carnedd Wen

Summit Height:  267.9m (converted to OSGM15)

Name:  Broniarth

OS 1:50,000 map:  125

Summit Grid Reference:  SJ 16648 12055

Drop:  21.5m (converted to OSGM15)


Broniarth (SJ 166 120) 200m Sub-Twmpau status now confirmed by the Trimble GeoXH 6000

For details on the survey that resulted in this hill being confirmed as a 200m Sub-Twmpau please click {here}

Myrddyn Phillips (January 2016)