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

Mynydd Carreg (SH 163 291) – 100m Twmpau reclassified to 30-99m Twmpau (8th reclassification)

Survey post for Mynydd Carreg


There has been a reclassification of a 100m Twmpau to a 30-99m Twmpau (thirty welsh metre prominences and upward) initiated by a survey with the Trimble GeoXH 6000.  The details relating to this hill’s reclassification are retrospective as the survey with the Trimble took place on the 28th December 2014.

The criteria for 100m Twmpau status is all Welsh hills at or above 100m and below 200m in height with 30m minimum drop, whilst the criteria for 30-99m Twmpau status is all Welsh hills at or above 30m and below 100m in height with 30m minimum drop.

When drop values were added to the original Welsh P30 lists that were published on Geoff Crowder’s v-g.me website, this hill was listed with an estimated c 95m summit height based on an uppermost 90m contour ring, and a bwlch height of c 54m, based on interpolation of bwlch contouring between 50m – 60m, with these values giving this hill c 41m of drop.  When the Ordnance Survey enlarged mapping hosted on the Geograph website became available online the whole of Wales was checked for new spot heights and as this hill was given a 100m summit spot height it was reclassified to the 100m P30 list, which was later renamed the 100m Twmpau.

Therefore, prior to the survey with the Trimble GeoXH 6000 this hill was listed with an estimated c 46m of drop based on its 100m summit spot height and an estimated c 53m bwlch height, based on interpolation of bwlch contouring between 50m – 55m.

The name of the hill is Mynydd Carreg and it is situated in the Pen Llŷn range of hills with its Cardinal Hill being Mynydd y Rhiw (SH 228 293and is placed in the North Wales Region (Region A, Sub-Region A1), and is positioned with the small community of Aberdaron to the south south-east of the hill.

As the summit of the hill is not a part of designated open access land permission to visit its high point should be sought.  However, as the summit is a local viewpoint with a car park at the foot of the hill it is likely that an ascent will have no objection.


The full details for the hill are:

Cardinal Hill:  Mynydd y Rhiw

Summit Height:  99.2m (converted to OSGM15)

Name:  Mynydd Carreg

OS 1:50,000 map:  123

Summit Grid Reference:  SH 16371 29168

Drop:  c 46m



The Trimble GeoXH 6000 gathering data at the summit of Mynydd Carreg


Myrddyn Phillips (September 2017)






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)

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