Mapping Mountains - Significant Height Revisions - Y Pedwarau
Moel Wnog (SH 735 440) - 24th significant height revision
Hill Reclassifications post for Moel Wnog
There has been a Significant Height Revision to a hill that is listed in the Y Pedwarau – The 400m Hills of Wales, with the summit height, bwlch height and their locations, the drop and status of the hill derived from detail produced by Joe Nuttall in his surface analysis progamme, with subsequent LIDAR analysis conducted by the DoBIH team and independently by Aled Williams and Myrddyn Phillips.
LIDAR image of Moel Wnog (SH 735 440) |
Y Pedwarau - The 400m Hills of Wales by Myrddyn Phillips and Aled Williams |
Extract from the Ordnance Survey 1:25,000 Explorer map |
LIDAR summit image of Moel Wnog (SH 735 440) |
The full details for the hill are:
Group: Arenig Fach
Name: Moel Wnog
OS 1:50,000 map: 124
Summit Height (New Height): 471.3m (LIDAR)
Summit Grid Reference: SH 73522 44084 (LIDAR)
Bwlch Height: 441.5m (LIDAR)
Bwlch Grid Reference: SH 73597 44355 (LIDAR)
Drop: 29.8m (LIDAR)
Myrddyn Phillips and Aled Williams (August 2023)
Mapping Mountains - Significant Height Revisions - Y Pedwarau
Ffridd Ddu (SH 726 064) - 23rd significant height revision
There has been a Significant Height Revision to a hill that is listed in the Y Pedwarau – The 400m Hills of Wales and Y Pellennig – The Remotest Hills of Wales, with the summit height, bwlch height and their locations, the drop, remoteness and status of the hill derived from LIDAR analysis conducted by Myrddyn Phillips.
LIDAR image of Ffridd Ddu (SH 726 064) |
Y Pedwarau - The 400m Hills of Wales by Myrddyn Phillips and Aled Williams |
Y Pellennig - The Remotest Hills of Wales by Myrddyn Phillips and Aled Williams |
Extract from the Ordnance Survey 1:25,000 Explorer map |
Extract from the interactive mapping hosted on the WalkLakes website |
LIDAR summit image of Ffridd Ddu (SH 726 064) |
The full details for the hill are:
Group: Tarren y Gesail
Name: Ffridd Ddu
OS 1:50,000 map: 124
Summit Height (New Height): 435.0m (LIDAR)
Summit Grid Reference: SH 72667 06467 (LIDAR)
Bwlch Height: 413.0m (LIDAR)
Bwlch Grid Reference: SH 72593 06527 (LIDAR)
Drop: 22.0m (LIDAR)
Remoteness: 2.590km
Myrddyn Phillips and Aled Williams (July 2023)
Mapping Mountains - Significant Height Revisions - Y Pedwarau
Stonewall Hill (SO 318 696) - 22nd significant height revision
1st survey post for Stonewall Hill
2nd survey post for Stonewall Hill
Hill Reclassifications post for Stonewall Hill
There has been a Significant Height Revision to a hill that is listed in the Y Pedwarau – The 400m Hills of Wales under the classification of National Top status (for details relating to the concept of National Tops see separate post), with the summit height, bwlch height and their locations, the drop and status of the hill confirmed by LIDAR analysis and a subsequent Trimble GeoXH 6000 survey conducted by Myrddyn Phillips and Aled Williams.
Stonewall Hill (SO 318 696) |
Y Pedwarau – The 400m Hills of Wales. Welsh hills at or above 400m and below 500m in height that have 30m minimum drop, accompanying the main Y Pedwarau list are five categories of sub hills, with this hill being included in the 400m Sub-Pedwar category. The criteria for 400m Sub-Pedwar status being all Welsh hills at or above 400m and below 500m in height that have 20m or more and below 30m of drop. The list is co-authored by Myrddyn Phillips and Aled Williams and is published on Mapping Mountains in Google Doc format.
Y Pedwarau - The 400m Hills of Wales by Myrddyn Phillips and Aled Williams |
Extract from the Ordnance Survey 1:25,000 Explorer map |
LIDAR image of Stonewall Hill (SO 318 696) |
The term Significant Height Revisions applies to any listed hill whose interpolated summit height and Ordnance Survey or Harvey map summit spot height has a 2m or more discrepancy when compared to the survey result produced by the Trimble GeoXH 6000 or analysis of data produced via LIDAR. Also included are hills whose summit map data is missing an uppermost ring contour when compared to the data produced by the Trimble or by LIDAR analysis.
The Trimble GeoXH 6000 gathering data at the summit of Stonewall Hill |
The full details for the hill are:
Group: Beacon Hill
Name: Stonewall Hill
OS 1:50,000 map: 137, 148
Summit Height (New Height): 400.1m (converted to OSGM15)
Summit Grid Reference: SO 31823 69655
Bwlch Height: 376.4m (converted to OSGM15)
Bwlch Grid Reference: SO 31273 70279
Drop: 23.8m
Cefn Sarnau (SO 014 341) - 21st significant height revision
LIDAR image of Cefn Sarnau (SO 014 341) |
Extract from the Ordnance Survey 1:25,000 Explorer map |
LIDAR summit image of Cefn Sarnau |
Mapping Mountains - Significant Height Revisions - Y Pedwarau
Grugfryn (SJ 248 356) - 20th significant height revision
Survey post for Grugfryn
Significant Name Changes post for Grugfryn
Summit Relocations post for Grugfryn
Grugfryn (SJ 248 356) |
Extract from the Ordnance Survey 1:25,000 Explorer map |
The Trimble GeoXH 6000 gathering data from the mound beside the indistinct forest track |
LIDAR summit image of Grugfryn |
Esgair Llwyn Gwyn (SN 885 790) - 19th significant height revision
Approaching the summit of Esgair Llwyn Gwyn (SN 885 790) |
The criteria for the list that this height revision applies to are:
Extract from the Ordnance Survey 1:50,000 Landranger map |
Extract from the Ordnance Survey 1:25,000 Explorer map |
LIDAR image of Esgair Llwyn Gwyn (SN 885 790) |
Gathering data at the summit of Esgair Llwyn Gwyn |
Gathering data at the bwlch of Esgair Llwyn Gwyn |
Therefore, the new listed summit height of this hill is 435.9m and this was derived from a Trimble GeoXH 6000 survey. This is not a dramatic revision in height compared to some revised heights and is 2.1m lower than the previous listed height of 438m which was derived from the summit spot height on the Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer maps.
Craig Celynin (SH 746 733) - 18th significant height revision
Survey post for Craig Celynin
Craig Celynin (SH 746 733) |
Extract from the Ordnance Survey 1:25,000 Explorer map |
The Trimble GeoXH 6000 gathering data at the summit of Craig Celynin |
Fuches (SN 866 836) - 17th significant height revision
Survey post for Fuches
Hill Reclassifications post for Fuches
The Trimble set-up position at the summit of Fuches which resulted in this hill's significant height revision |
Mapping Mountains - Significant Height Revisions - Y Pedwarau
Twyn y Waun (SO 085 065) - 16th significant height revision
Survey post for Twyn y Waun
Hill Reclassifications post for Twyn y Waun
The Trimble GeoXH 6000 gathering data at the summit of Twyn y Waun (SO 085 065) which resulted in this hill's significant height revision |
Mapping Mountains - Significant Height Revisions - Y Pedwarau
Twyn y Waun (SO 082 070) - 15th significant height revision
Survey post for Twyn y Waun
The Trimble GeoXH 6000 gathering data at the man-made Dual Summit of Twyn y Waun (SO 08209 07041) which resulted in this summit's significant height revision |
Mapping Mountains - Significant Height Revisions - Y Pedwarau
Pawl Hir (SO 101 595) - 14th significant height revision
Survey post for Pawl Hir
Summit Relocation post for Pawl Hir
Pawl Hir (SO 101 595) |
Extract from the Ordnance Survey Interactive Coverage Map hosted on the Geograph website |
The Trimble GeoXH 6000 gathering data at the northerly high point of this hill which resulted in this point's significant height revision |
Mapping Mountains - Significant Height Revisions - Y Pedwarau
Mynydd Epynt (SN 961 464) - 13th significant height revision
Survey post for Mynydd Epynt
1st significant Name Changes post
2nd Significant Name Changes post
The criteria for the two listings that this height revision affects are:
Y Pedwarau - Welsh hills at and above 400m and below 500m in height that have 30m minimum drop.
Y Trechol - The Dominant Hills of Wales - These are the Welsh P30 hills whose prominence equal or exceed half that of their absolute height. With the criteria for Lesser Dominant status being those addition Welsh P30 hills whose prominence is 33% or more and below 50% of their absolute height.
The name of the hill is Mynydd Epynt and it is situated in the hills of Mynydd Epynt in the south-easterly part of Mid and West Wales (Region B, Sub-Region B2), and the survey was conducted on a beautiful winter’s morning with blue sky, frost and just a breath of breeze. Large swathes of Mynydd Epynt is out of bounds for much of the year as it forms part of the Sennybridge Artillery Range Firing Area, and the hill range is positioned between those of Mynydd Du, Fforest Fawr, Bannau Brycheiniog (Brecon Beacons) and Mynyddoedd Duon (Black Mountains) to its south and the wilds of the Elenydd to its north.
Summit Height: 475.5m
Dominance: 41.62%
The Trimble GeoXH 6000 gathering data at the summit of Mynydd Epynt (SN 961 464) which confirmed this hill's significant height revision |
Mapping Mountains - Significant Height Revisions - Y Pedwarau
Moelfre (SH 717 744) - 12th significant height revision
Survey post for Moelfre
Hill Reclassifications post for Moelfre
There has been a Significant Height Revision initiated by a survey with the Trimble GeoXH 6000 to a hill listed in the Y Pedwarau, and which was subsequently confirmed by LIDAR analysis conducted by Aled Williams, with the survey that resulted in this height revision being conducted on the 4th July 2016.
LIDAR image of Moelfre (SH 717 744) |
The criteria for the listing that this height revision affects are:
Y Pedwarau - Welsh hills at and above 400m and below 500m in height that have 30m minimum drop.
400m Sub- Pedwarau - Welsh hills at and above 400m and below 500m in height that have 20m or more and below 30m of drop.
The name of the hill is Moelfre and it is situated in the Carneddau range of hills which are in north-west Wales. This hill range comprises some of the highest mountains in the country but the evening walk when the survey was conducted concentrated on some of its 300m and 400m lower hills.
The Trimble GeoXH 6000 gathering data at the summit of Moelfre (SH 717 744) which resulted in this hill's significant height revision |
Mapping Mountains - Significant Height Revisions - Y Pedwarau
Clip yr Orsedd (SH 711 747) - 11th significant height revision
Survey post for Clip yr Orsedd
The Trimble GeoXH 6000 gathering data at the summit of Clip yr Orsedd (SH 711 747) which resulted in this hill's significant height revision |
Mapping Mountains - Significant Height Revisions - Y Pedwarau
Penmaen Mawr (SH 698 755) - 10th significant height revision
Survey post for Penmaen Mawr
Hill Reclassifications post for Penmaen Mawr
There has been a Significant Height Revision initiated by a survey with the Trimble GeoXH 6000 to a hill that is listed in the Y Pedwarau and the Y Trichant, with the survey that resulted in this height revision being conducted on the 14th July 2016.
The criteria for the listings that this height revision affects are:
Y Pedwarau - Welsh hills at and above 400m and below 500m in height that have 30m minimum drop. 300m Double Sub- Pedwarau - Welsh hills at and above 390m and below 400m in height that have 20m or more and below 30m of drop. The list is co-authored by Myrddyn Phillips and Aled Williams.
Y Trichant - Welsh hills at and above 300m and below 400m in height that have 30m minimum drop. Sub-Trichant - Welsh hills at and above 300m and below 400m in height that have 20m or more and below 30m of drop. The list is authored by Myrddyn Phillips and the Introduction to the list and its re-naming has been published on Mapping Mountains.
The hill is named Penmaen Mawr and it is situated in the Carneddau range of hills, and is positioned above and to the immediate south of the busy A 55 as it heads westward between the towns of Penmaenmawr and Llanfairfechan, which are situated to the hill’s east and west respectively.
The summit area of Penmaen Mawr has been quarried, and prior to the first quarry opening in 1830 and the subsequent resulting expansion of operations the hill was substantially higher, with a 1,550ft (472m) map height given it on the Ordnance Survey Popular and New Popular One-Inch maps, with this height also appearing on the Ordnance Survey Six-Inch map published in 1888.
Penmaen Mawr: 390.4m (converted to OSGM15, Trimble GeoXH 6000) at SH 69865 75523
The Trimble GeoXH 6000 gathering data 0.39m above the summit of Penmaen Mawr (SH 698 755) which resulted in this hill's significant height revision |
Mapping Mountains - Significant Height Revisions - Y Pedwarau
Craig y Garreg Lwyd (SH 730 427) - 9th significant height revision
Survey post for Craig y Garreg Lwyd
1st Hill Reclassifications post for Craig y Garreg Lwyd
2nd Hill Reclassifications post for Craig y Garreg Lwyd
There has been a Significant Height Revision initiated by a survey with the Trimble GeoXH 6000 to the listing of the Y Pedwarau, and which was later confirmed by a survey with a Leica GS15, with these details being retrospective as the survey that resulted in this height revision was conducted on 14th March 2016 in good, bright conditions, albeit with a chilling easterly breeze blowing .
The criteria for the listing that this height revision affects are:
Y Pedwarau - Welsh hills at and above 400m and below 500m in height that have 30m minimum drop.
400m Sub- Pedwarau - Welsh hills at and above 400m and below 500m in height that have 20m or more and below 30m of drop.
The hill is named Craig y Garreg Lwyd and it is situated in the Arenig group of hills between the Moelwynion to the west and the wilds of Y Migneint to the east, with these hills situated in north-west Wales.
Prior to the survey with the Trimble GeoXH 6000 Craig y Garreg Lwyd was listed as a Pedwar with 35m of drop based on the 478m and 443m spot heights that appear on the summit and bwlch respectively on the Ordnance Survey enlarged mapping hosted on the Geograph website.
Craig y Garreg Lwyd was subsequently surveyed by John Barnard and Graham Jackson using a Leica GS15 resulting in a 473.8m (converted to OSGM15) summit height and a 443.6m (converted to OSGM15) bwlch height.
Gathering data at the summit of Craig y Garreg Lwyd (SH 730 427) which resulted in this hill's significant height revision |
Mapping Mountains - Significant Height Revisions - Y Pedwarau
Pt. 483.6m (SH 735 428) - 8th significant height revision
Survey post for Pt. 483.6m
Summit Relocations post for Pt. 483.6m
There has been a Significant Height Revision initiated by a survey with the Trimble GeoXH 6000 to a hill that is listed in the Y Pedwarau, with the survey that resulted in this height revision being conducted on 14th March 2016. The criteria for Pedwar status being all Welsh hills at or above 400m and below 500m in height that have 30m minimum drop.
The hill is currently listed under the point (Pt. 483.6m) notation as it is not named on Ordnance Survey maps, although the hill is positioned next to the small mountain lake of Llyn y Drum.
The hill is situated in the Arenig group of hills and is positioned between the hills of the Moelwynion and the Migneint in north-west Wales, and the survey was conducted on a beautiful sunny, albeit chilly, early spring day.
Gathering data at the summit of Pt. 483.6m which resulted in this hill's significant height revision |
Mapping Mountains - Significant Height Revisions - Y Pedwarau
Cwm Cynnydd Bank (SO 061 726) - 7th significant height revision
Survey post for Cwm Cynnydd Bank
Significant Name Changes post for Cwm Cynnydd Bank
There has been a Significant Height Revision to a hill that is listed in the Y Pedwarau that was initiated by a survey with the Trimble GeoXH 6000, with the survey that resulted in this height revision being conducted on 18th February 2016. The criteria for Pedwar status being all Welsh hills at or above 400m and below 500m in height that have 30m minimum drop.
The name of the hill is Cwm Cynnydd Bank and it is situated in the hills of the Pegwn Mawr range which is positioned in mid Wales and the survey was conducted during a walk taking in one Trichant and three Pedwar hills.
Gathering data at the summit of Cwm Cynnydd Bank (SO 061 727) which resulted in this hill's significant height revision |
Mapping Mountains - Significant Height Revisions - Y Pedwarau
Cerrig y Gordref (SH 929 428) - 6th significant height revision
Survey post for Cerrig y Gordref
Summit Relocations post for Cerrig y Gordref
There has been a Significant Height Revision to a hill that is listed in the Y Pedwarau that was initiated by a survey with the Trimble GeoXH 6000, with these details being retrospective as the survey that resulted in this height revision was conducted on 2nd October 2015.
The criteria for Pedwar status is all Welsh hills at or above 400m and below 500m in height that have 30m minimum drop. Whilst the criteria for 400m Sub-Pedwar status is all Welsh hills at or above 400m and below 500m in height that have 20m or more and below 30m of drop.
The name of the hill is Cerrig y Gordref and it is situated in the Arenig group of hills, and is positioned between the towns of Y Bala to the south and Cerrigydrudion to the north north-east. The hill was surveyed in the company of Aled Williams who had suggested the walk.
The hill was listed in the Y Pedwarau (Europeaklist May 2013) as a 400m Sub-Pedwar with 28m of drop based on the 497m spot height at SH 93066 42836 that appears on Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer maps and the 469m spot height at the bwlch that is positioned at SH 93210 42714 on Ordnance Survey 1:25,000 Explorer maps. However, the summit area of this hill also has a 495m spot height at SH 92974 42817 that appears on the Ordnance Survey enlarged mapping hosted on the Geograph website.
Gathering data at the summit of Cerrig y Gordref which resulted in this hill's significant height revision |
Mapping Mountains - Significant Height Revisions - Y Pedwarau
Bryn Serth (SO 148 109) - 5th significant height revision
Survey post for Bryn Serth
Hill Reclassifications post for Bryn Serth
Summit Relocations post for Bryn Serth
There has been a Significant Height Revision to a hill that is listed in the Y Pedwarau that was initiated by a survey with the Trimble GeoXH 6000 and subsequently confirmed via LIDAR analysis conducted by Aled Williams, with these details being retrospective as the Trimble survey that resulted in this height revision was conducted on 12th August 2015.
The criteria for Pedwar status is all Welsh hills at or above 400m and below 500m in height that have 30m minimum drop. Whilst the criteria for 400m Sub-Pedwar status is all Welsh hills at or above 400m and below 500m in height that have 20m or more and below 30m of drop.
Gathering data at the summit of Bryn Serth which resulted in this hill's significant height revision |
Mapping Mountains - Significant Height Revisions - Y Pedwarau
Mynydd Poeth (SH 953 513) - 4th significant height revision
Survey post for Mynydd Poeth
Hill Reclassifications post for Mynydd Poeth
Summit Relocations post for Mynydd Poeth
There has been a Significant Height Revision to a hill that is listed in the Y Pedwarau and which was initiated by a survey with the Trimble GeoXH 6000, with these details being retrospective as the survey that resulted in this height revision was conducted on 24th December 2014. The hill appeared in the listing of Y Pedwarau as a 400m Sub-Pedwar with c 29m of drop and was reclassified to a Pedwar due to the survey with the Trimble GeoXH 6000.
The criteria for Pedwar status is all Welsh hills at or above 400m and below 500m in height that have 30m minimum drop. Whilst the criteria for 400m Sub-Pedwar status is all Welsh hills at or above 400m and below 500m in height that have 20m or more and below 30m of drop.
Gathering data from the summit of Mynydd Poeth which resulted in this hill's significant height revision |
Mapping Mountains - Significant Height Revisions - Y Pedwarau
Bryn Melyn (SO 109 184) - 3rd significant height revision
Survey post for Bryn Melyn
There has been a Significant Height Revision to a hill listed in the Y Pedwarau initiated from a survey with the Trimble GeoXH 6000, with these details being retrospective as the survey that resulted in this height revision was conducted on the 22nd July 2014. With the criteria for Pedwar status being all Welsh hills at or above 400m and below 500m in height that have a minimum 30m of drop.
Gathering data from the summit of Bryn Melyn which resulted in this hill's significant height revision |
Mapping Mountains - Significant Height Revisions - Y Pedwarau
Craig y Ganllwyd (SH 707 258) - 2nd significant height revision
Survey post for Craig y Ganllwyd
Hill Reclassifications post for Craig y Ganllwyd
There has been a Significant Height Revision to the listing of the Y Pedwarau initiated from a survey with the Trimble GeoXH 6000, with these details being retrospective as the survey that resulted in this height revision was conducted on 3rd May 2014. With the criteria for Pedwar status being all Welsh hills at or above 400m and below 500m in height that have a minimum of 30m of drop.
Gathering data from the summit of Craig y Ganllwyd which resulted in this hill's significant height revision |
Mapping Mountains - Significant Height Revisions - Y Pedwarau
Craig y Derlwyn (SH 702 259) - 1st significant height revision
Survey post for Craig y Derlwyn
There has been a Significant Height Revision initiated by a survey with the Trimble GeoXH 6000 to the listing of the Y Pedwarau, with these details being retrospective as the survey that resulted in this height revision was conducted on 3rd May 2014.
The criteria for the listing that this height revision affects are:
Y Pedwarau - Welsh hills at or above 400m and below 500m in height that have 30m minimum drop.
400m Sub- Pedwarau - Welsh hills at or above 400m and below 500m in height that have 20m or more and below 30m of drop.
Gathering data at the summit of Craig y Derlwyn |
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