The Y
Pedwarau list has been updated with the Tarennydd group of hills
Friday, 30 June 2017
Thursday, 29 June 2017
Mapping Mountains – Hill Reclassifications – 30-99m Twmpau
Ynys Gron (SH 596 392) – 30-99m Twmpau reclassified to 30-99m
Sub-Twmpau
There has been a reclassification to the Twmpau (thirty welsh metre prominences and upward) list with a 30-99m Twmpau being reclassified to a 30-99m Sub-Twmpau due to surveying 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 21th November 2014.
The criteria for 30-99m
Twmpau status is all Welsh hills at or above 30m and below 100m in height
with 30m minimum drop, whilst the criteria for 30-99m Sub-Twmpau status is all Welsh hills at or above 30m and
below 100m in height with 20m or more and below 30m of drop.
The hill had been listed in the original Welsh P30
lists when published on Geoff Crowder’s v-g.me website with a 96m summit height
based on the Ordnance Survey 1:25,000 Outdoor Leisure spot height, with an
accompanying note stating ‘98m on 1984
1:50,000 map. Summit being reduced due
to quarrying’. When drop values were
added to the P30 Master Lists this hill was given an estimated drop of c 50m. The
heights quoted appeared on maps of the day, although it was also known that the
quarrying activities had already reduced the height of this hill.
The hill is situated in the Moelwynion group of hills and is placed
in the Region of North Wales (Region A, Sub-Region A1) with its Cardinal Hill
being Moelwyn Mawr (SH 658 448) and
is situated between the towns of Porthmadog
to the west and Penrhyndeudraeth
to the east, and immediately above the busy A 487 road which is to its south.
The hill is not on open access
land and the whole of its south-western section forms part of the Garth Quarry, which is operational, and because
of this permission to visit should be sought.
However, the approach from the east is through woodland and would take a
visitor direct to the remaining high point of the hill.
The name of the hill is Ynys Gron, which is a locally known name
and it has been reclassified to a 30-99m
Sub-Twmpau as the quarry has now obliterated the upper 30m of the hill and
reduced it in height to 69.4m, and as its bwlch has been surveyed as 44.3m in
height, it gives this hill only 25.1m of drop, which is insufficient for it to
remain classified as a P30.
The full details for the hill are:
Cardinal Hill: Moelwyn
Mawr
Summit Height: 69.4m
(converted to OSGM15)
Name: Ynys Gron
OS 1:50,000 map: 124
Summit Grid Reference:
SH 59653 39268
Drop: 25.1m (converted
to OSGM15)
 |
| The Trimble GeoXH 6000 gathering data at the remaining high point of Ynys Gron |
Myrddyn Phillips (June 2017)
Wednesday, 28 June 2017
Mapping Mountains – Hill Reclassifications – 30-99m Twmpau
30-99m
Twmpau – Hill Reclassifications
The 30-99m Twmpau (thirty welsh metre prominences and upward) are the Welsh hills at or above 30m and
below 100m in height that have a minimum drop of 30m. Accompanying the main P30 list are two sub
lists entitled the 30-99m Sub-Twmpau
with the qualification to this sub category being all Welsh hills at or above
30m and below 100m in height with 20m or more and below 30m of drop, and the Double Sub-Twmpau with the qualification
to this sub category being all Welsh hills at or above 20m and below 30m in
height with 20m or more and below 30m of drop.
Mapping Mountains - Hill Reclassifications - 30-99m Twmpau
Yr Orsedd (SH 299 270) – 30–99m Sub-Twmpau reclassified to 30-99m Twmpau (35th reclassification)
Survey post for Yr Orsedd
Significant Name Changes post for Yr Orsedd
Summit Relocations post for Yr Orsedd
There has been confirmation of a Hill Reclassification to the list of 30-99m Twmpau, with the summit height, its location, the drop and status of the hill confirmed by LIDAR analysis, and a subsequent summit survey with the Trimble GeoXH 6000 conducted by Myrddyn Phillips, with the latter taking place on the 3rd October 2018.
 |
| Yr Orsedd (SH 299 270) |
The criteria for the list that this reclassification applies to are:
30-99m Twmpau - Welsh hills at or above 30m and below 100m in height with 30m minimum drop, with an accompanying sub list entitled the 30-99m Sub-Twmpau with the criteria for this sub category being all Welsh hills at or above 30m and below 100m in height with 20m or more and below 30m of drop, with the word Twmpau being an acronym standing for thirty welsh metre prominences and upward.
When the original Welsh P30 hills were published on Geoff Crowder’s v-g.me website this hill appeared in the accompanying Hills to be surveyed sub list as it did not meet the criteria then used for the main P30 list; however this sub list has now been standardised with drop values and interpolated heights also included in the main P30 and the accompanying sub list.
When this list was standardised with interpolated heights and drop values included this hill was listed with c 31m of drop based on the 64m summit spot height positioned at SH 295 266 on the Ordnance Survey 1:25,000 Explorer map and an estimated bwlch height of c 33m based on interpolation of 10m bwlch contouring.
 |
| Extract from the Ordnance Survey 1:25,000 Explorer map |
The details for this hill were reassessed when the Ordnance Survey Interactive Coverage Map hosted on the Geograph website became available online, and this map has a 66m spot height at SH 299 270 which is adjoined to the hill to the north-east, which only has an uppermost 60m ring contour on the 1:25,000 Explorer map. Therefore the summit position of the listed hill was relocated and its drop value increased accordingly, with the Interactive Coverage Map also giving the south-westerly hill a second 64m map heighted summit.
 |
| Extract from the Ordnance Survey Interactive Coverage Map hosted on the Geograph website |
Prior to the Trimble GeoXH 6000 summit survey this hill and its adjoining south-westerly 64m twin map heighted hill were analysed via LIDAR, and this confirmed that the north-easterly summit is the higher.
The locally known name of the higher summit is Yr Orsedd, whilst the lower south-westerly summit is known locally as Bryn Tŷ Newydd, and it is adjoined to the Pen Llŷn group of hills, which are situated in the western part of North Wales (Region A, Sub-Region A1), and the hill is encircled by minor roads with the coast to its south-west and east, and has the village of Abersoch towards its north-east.
 |
| Bryn Tŷ Newydd, the old listed summit to the south-west |
As the summit of this hill is not a part of designated open access land permission to visit should be sought, for those wishing to do so the easiest approach is via the east using gates to access the summit.
The confirmation of the reclassification of Yr Orsedd to 30-99m Twmpau status is due to LIDAR analysis and a summit survey with the Trimble GeoXH 6000 conducted by Myrddyn Phillips, resulting in a 67.5m summit height and a 32.0m bwlch height, with these values giving this hill 35.4m of drop which is sufficient for it to be classified as a 30-99m Twmpau.
 |
| The Trimble GeoXH 6000 gathering data at the summit of Yr Orsedd |
The full details for the hill are:
Group: Pen Llŷn
Name: Yr Orsedd
OS 1:50,000 map: 123
Summit Height: 67.5m (converted to OSGM15)
Summit Grid Reference: SH 29952 27038
Bwlch Height: 32.0m (LIDAR)
Bwlch Grid Reference: SH 29808 27337 (LIDAR)
Drop: 35.4m (Trimble summit and LIDAR bwlch)
Myrddyn Phillips (February 2019)
Mapping Mountains - Hill Reclassifications - 30-99m Twmpau
Bryn (SH 426 361)
Survey post for Bryn
Significant Name Changes post for Bryn
Summit Relocations post for Bryn
There has been confirmation of a Hill Reclassification to the list of 30-99m Twmpau, with the hill suggested as a P30 by Chris Pearson in February 2018 and its status confirmed by LIDAR analysis conducted by Chris Crocker. The hill was subsequently analysed using LIDAR and surveyed with the Trimble GeoXH 6000 by Myrddyn Phillips, with the latter taking place on the 10th September 2018.
 |
| LIDAR image of Bryn |
The criteria for the list that this reclassification applies to are:
30-99m Twmpau - Welsh hills at or above 30m and below 100m in height with 30m minimum drop, with an accompanying sub list entitled the 30-99m Sub-Twmpau with the criteria for this sub category being all Welsh hills at or above 30m and below 100m in height with 20m or more and below 30m of drop, with the word Twmpau being an acronym standing for thirty welsh metre prominences and upward.
When the original Welsh P30 hills were published on Geoff Crowder’s v-g.me website this hill appeared in the accompanying Hills to be surveyed sub list as it did not meet the criteria then used for the main P30 list; however this sub list has now been standardised with drop values and interpolated heights also included in the main P30 and the accompanying sub list.
When this list was standardised and interpolated heights also included this hill was listed with an estimated c 28m of drop, based on the 36m summit spot height that appears on the Ordnance Survey 1:25,000 Explorer map and an estimated bwlch height of c 8m based on interpolation of bwlch contouring between 0 – 10m.
 |
| Extract from the Ordnance Survey 1:25,000 Explorer map |
These values were re-evaluated when the Ordnance Survey Interactive Coverage Map hosted on the Geograph website became available online, and as this map has 5m contour intervals the bwlch contouring was reassessed. However, as there is a rail line passing through this bwlch the contours on this map are not continuous and could in affect be between 0 – 5m or between 5m – 10m at the critical point of the bwlch, they were taken as being between 5m – 10m with an estimated c 7m height for the bwlch, giving this hill c 29m of drop.
 |
| Extract from the Ordnance Survey Interactive Coverage Map hosted on the Geograph website |
The locally known name of the hill is Bryn, and this is the name it is now listed by, and it is adjoined to the Pen Llŷn group of hills, which are situated in the western part of North Wales (Region A, Sub-Region A1), and is positioned overlooking the sea to its south and the A 497 road to its north, and has the town of Pwllheli towards the west.
As the summit of this hill is not a part of designated open access land permission to visit should be sought, for those wishing to do so a public footpath approaches the hill from its north and access to the summit is relatively easy from here via its north-west which avoids the majority of gorse on its upper slopes.
Prior to the Trimble GeoXH 6000 survey this hill’s summit and bwlch contours were analysed with LIDAR, with the conclusion that the hill is not a natural P30 as LIDAR bwlch contouring implies that the natural bwlch would once have been over 7m in height. This bwlch is now reduced in height due to a railway cutting.
An appropriate name for the hill was also researched via the Tithe map, finding that the upper section of the hill which now comprises one field, used to comprise two, with the boundary between each showing as a slight elevation on LIDAR. This boundary although old, is not ancient, and would be a man-made construction. LIDAR also shows that the natural summit of this hill still exists, close to the old field boundary. Therefore I wanted to take data sets from the slightly raised field boundary, and the natural summit with LIDAR giving two potential positions for this, with one adjacent to the old field boundary and the other a few metres distant from it.
 |
| LIDAR image for the summit area of Bryn |
Therefore, three data sets were taken with the Trimble GeoXH 6000 from the summit area of this hill, resulting in:
1st survey: 36.750m at SH 42673 36171 (raised old field boundary)
2nd survey: 36.5965m at SH 42668 36171 (average of two surveys)
3rd survey: 36.675m at SH 42656 36173 (natural summit)
Therefore, the height produced by the Trimble GeoXH 6000 survey to the natural summit of this hill is 36.7m and is positioned at SH 42656 36173, with LIDAR analysis giving a 6.6m bwlch height positioned at SH 43103 36535, with these values giving this hill 30.0m of drop, which confirms its 30-99m Twmpau status.
 |
| Gathering data with the Trimble GeoXH 6000 at the summit of Bryn |
The full details for the hill are:
Group: Pen Llŷn
Name: Bryn
OS 1:50,000 map: 123
Summit Height: 36.7m (converted to OSGM15) (natural summit)
Summit Grid Reference: SH 42656 36173 (natural summit)
Bwlch Height: 6.6m (LIDAR)
Bwlch Grid Reference: SH 43103 36535 (LIDAR)
Drop: 30.0m (Trimble summit and LIDAR bwlch)
My thanks to Chris Pearson for suggesting this hill as a P30 and to Chris Crocker for initial LIDAR analysis
Myrddyn Phillips (February 2019)
Mapping Mountains - Hill Reclassifications - 30-99m Twmpau
Tor Gro (SS 462 934) – 30-99m Twmpau addition (33rd reclassification)
There has been confirmation of an addition to the list of 30-99m Twmpau due to LIDAR analysis conducted by Myrddyn Phillips.
 |
| LIDAR image of Tor Gro |
The criteria for the listing that this addition applies to are:
30-99m Twmpau - Welsh hills at or above 30m and below 100m in height with 30m minimum drop, with an accompanying sub list entitled the 30-99m Sub-Twmpau with the criteria for this sub category being all Welsh hills at or above 30m and below 100m in height with 20m or more and below 30m of drop, with the word Twmpau being an acronym standing for thirty welsh metre prominences and upward.
This hill did not appear in the original Welsh P30 lists when published on Geoff Crowder’s v-g.me website, even though map details gave it 30m of drop with a 79m summit and 49m bwlch spot height that appear on the Ordnance Survey 1:25,000 Explorer map.
 |
| Extract from the Ordnance Survey 1:25,000 Explorer map |
The details relating to this hill were soon readdressed when these lists were standardised and drop values and interpolated heights included, and it then appeared as a P30 and was later also included as a Lesser Dominant when the Gŵyr group of hills were initially listed on the 07.05.12.
The name of the hill is Tor Gro, and it is adjoined to the Gŵyr group of hills, which are situated in the western part of South Wales (Region C, Sub-Region C1), and it is positioned overlooking the Landimore Marsh to its north and the Burry Pill stream to its south, and has the small community of Llanmadog towards the west and Landimore towards the south-east.
If wanting to visit this hill permission to do so should be sought as it is not a part of designated open access land, for those wishing to do so the nearest public footpath giving access toward the summit is to the south and south-east of it.
The confirmation of this addition is due to LIDAR analysis conducted by Myrddyn Phillips. The LIDAR (Light Detection & Ranging) technique produced highly accurate height data that is now freely available for much of England and Wales.
The LIDAR analysis gives the hill the following details:
Name: Tor Gro
Summit Height: 79.6m
Summit Grid Reference: SS 46245 93479
Bwlch Height: 48.1m
Bwlch Grid Reference: SS 46183 92937
Drop: 31.6m
Therefore, the 79.6m LIDAR analysis for the summit position at SS 46245 93479 and the 48.1m LIDAR analysis for the bwlch position at SS 46183 92937 gives this hill 31.6m of drop, which confirms its 30-99m Twmpau status.
 |
| LIDAR summit image of Tor Gro |
The full details for the hill are:
Group: Gŵyr
Name: Tor Gro
OS 1:50,000 map: 159
Summit Height: 79.6m (LIDAR)
Summit Grid Reference: SS 46245 93479 (LIDAR)
Bwlch Height: 48.1m (LIDAR)
Bwlch Grid Reference: SS 46183 92937 (LIDAR)
Drop: 31.6m (LIDAR)
Mapping Mountains - Hill Reclassifications - 30-99m Twmpau
West Park (SR 940 990) – 30-99m Sub-Twmpau reclassified to 30-99m Twmpau (32nd reclassification)
Significant Name Changes post for West Park
There has been confirmation of a reclassification to the list of 30-99m Twmpau due to LIDAR analysis conducted by Myrddyn Phillips.
The criteria for the listing that this reclassification applies to are:
30-99m Twmpau - Welsh hills at or above 30m and below 100m in height with 30m minimum drop, with an accompanying sub list entitled the 30-99m Sub-Twmpau with the criteria for this sub category being all Welsh hills at or above 30m and below 100m in height with 20m or more and below 30m of drop, with the word Twmpau being an acronym standing for thirty welsh metre prominences and upward.
 |
| LIDAR image of West Park |
When the original Welsh P30 hills were published on Geoff Crowder’s v-g.me website this hill appeared in the accompanying Hills to be surveyed sub list as it did not meet the criteria then used for the main P30 list; however this sub list has now been standardised and interpolated heights also included in the main P30 and the accompanying sub list.
When this list was standardised and interpolated heights also included this hill was listed with an estimated c 30m of drop, based on an estimated c 82m summit height and an estimated bwlch height of c 52m based on 5m contouring on the Ordnance Survey 1:25,000 Explorer map.
 |
| Extract from the Ordnance Survey 1:25,000 Explorer map |
The bounded land where the summit of this hill is situated is named as West Park on the Tithe map, and this is the name the hill is now listed by, and it is adjoined to the Brandy Hill group of hills, which are situated in the south-western part of Mid and West Wales (Region B, Sub-Region B4), and is positioned between the B roads of the 4320 to the north and the 4319 to the south, and has the town of Penfro (Pembroke) towards the north-east.
If wanting to visit this hill permission to do so should be sought as it is not a part of designated open access land, for those wishing to do so the most convenient approach would be from a minor road to the west of the summit.
The confirmation of this reclassification is due to LIDAR analysis conducted by Myrddyn Phillips. The LIDAR (Light Detection & Ranging) technique produced highly accurate height data that is now freely available for much of England and Wales.
The LIDAR analysis gives the hill the following details:
Name: West Park
Summit Height: 81.7m
Summit Grid Reference: SR 94023 99001
Bwlch Height: 51.3m
Bwlch Grid Reference: SR 94747 99655
Drop: 30.4m
Therefore, the 81.7m LIDAR analysis for the summit position at SR 94023 99001 and the 51.3m LIDAR analysis for the bwlch position at SR 94747 99655 gives this hill 30.4m of drop, which confirms its 30-99m Twmpau status.
The full details for the hill are:
Group: Brandy Hill
Name: West Park
OS 1:50,000 map: 158
Summit Height: 81.7m (LIDAR)
Summit Grid Reference: SR 94023 99001 (LIDAR)
Bwlch Height: 51.3m (LIDAR)
Bwlch Grid Reference: SR 94747 99655 (LIDAR)
Drop: 30.4m (LIDAR)
Myrddyn Phillips (December 2018)
Mapping Mountains - Hill Reclassifications - 30-99m Twmpau
Hidden Slabs Stack (SS 119 982) – 30-99m Twmpau deletion (31st reclassification)
There has been confirmation of a deletion to the 30-99m Twmpau list due to LIDAR analysis conducted by Myrddyn Phillips, with the criteria for this list being:
30-99m Twmpau - Welsh hills at or above 30m and below 100m in height with 30m minimum drop, with an accompanying sub list entitled the 30-99m Sub-Twmpau with the criteria for this sub category being all Welsh hills at or above 30m and below 100m in height with 20m or more and below 30m of drop, with the word Twmpau being an acronym standing for thirty welsh metre prominences and upward.
This hill was included in the original Welsh P30 lists that were published on Geoff Crowder’s v-g.me website and given an estimated summit height of c 30m. When compiling these lists I contacted Dave Viggers in relation to sea stacks positioned around the Pembrokeshire coast, regarding their height, location and name. Dave is now a Vice President of the Climber’s Club and gave me information including the location of this hill, its approximate height and its name, which he advised was known as Hidden Slabs Stack. However, site visits to this location by a number of people including Jon Glew, Douglas Law, Rob Woodall and Adrian Rayner have brought in to doubt the existence of a sea stack at this point, and if anything did exist its height was estimated to be far lower than the listed c 30m.
The name of this hill is Hidden Slabs Stack, and as its name and LIDAR analysis implies it is a sea stack. The hill is adjoined to the Brandy Hill group of hills, which are situated in the south-western part of Mid and West Wales (Region B, Sub-Region B4), and is positioned with the coast to its immediate south and has the A 4139 road and the small community of Penally to its north-west.
If wanting to visit this hill permission to do so should be sought as it is not a part of designated open access land, for those wishing to do so the Pembrokeshire Coast Path is positioned to the north of the hill, but caution is advised as the easiest approach may necessitate some form of climbing.
The confirmation of the deletion of Hidden Slabs Stack from 30-99m Twmpau status is due to LIDAR analysis conducted by Myrddyn Phillips. The LIDAR (Light Detection & Ranging) technique produced highly accurate height data that is now freely available for much of England and Wales.
 |
| 2m DTM LIDAR image of Hidden Slabs Stack |
 |
| 1m DSM LIDAR image of Hidden Slabs Stack |
The 1m DSM LIDAR analysis gives the hill the following details:
Name: Hidden Slabs Stack
Summit Height: 6.5m
Summit Grid Reference: SS 11902 98247
Bwlch Height: N/A
Bwlch Grid Reference: N/A
Drop: 6.5m
Therefore, the 6.5m LIDAR analysis for the summit position at SS 11902 98247 gives this hill 6.5m of drop, which is insufficient for continued 30-99m Twmpau status.
 |
| LIDAR image of the summit of Hidden Slabs Stack |
The full details for the hill are:
Group: Brandy Hill
Name: Hidden Slabs Stack
OS 1:50,000 map: 158
Summit Height: 6.5m (LIDAR)
Summit Grid Reference: SS 11902 98247 (LIDAR)
Bwlch Height: N/A
Bwlch Grid Reference: N/A
Drop: 6.5m (LIDAR)
Myrddyn Phillips (October 2018)
Mapping Mountains - Hill Reclassifications - 30-99m Twmpau
No Name Stack (SR 975 932) – 30-99m Twmpau reclassified to 30-99m Sub-Twmpau (30th reclassification)
There has been a reclassification to the 30-99m Twmpau list due to LIDAR analysis conducted by Myrddyn Phillips, with the criteria for this list being:
30-99m Twmpau - Welsh hills at or above 30m and below 100m in height with 30m minimum drop, with an accompanying sub list entitled the 30-99m Sub-Twmpau with the criteria for this sub category being all Welsh hills at or above 30m and below 100m in height with 20m or more and below 30m of drop, with the word Twmpau being an acronym standing for thirty welsh metre prominences and upward.
Prior to LIDAR analysis this hill was listed with 30m of drop based on the 30m spot height that appears on the Ordnance Survey 1:25,000 Explorer map, with the height of the bwlch accepted as that for Ordnance Datum Newlyn (sea level), however map data indicates that this hill is adjoined to the mainland and is not tidal, indicating that its status as a P30 was debatable.
When the original Welsh P30 lists were compiled I contacted Dave Viggers in relation to sea stacks positioned around the Pembrokeshire coast, regarding their height, location and name. Dave is now a Vice President of the Climber’s Club and gave me invaluable information including the location of this hill, its approximate height and its name, which he advised was known as No Name Stack.
The name of this hill is No Name Stack, and although its name implies that it is a sea stack, it is adjoined to the mainland. The hill is adjoined to the Brandy Hill group of hills, which are situated in the south-western part of Mid and West Wales (Region B, Sub-Region B4), and is positioned with the coast to its immediate south-east and has St Govan’s Head to its south and Broad Haven towards its north north-east, and has the village of Bosherston towards its north-west.
If wanting to visit this hill permission to do so should be sought as it is not a part of designated open access land, for those wishing to do so caution is advised as the easiest approach will necessitate some form of climbing.
The reclassification of No Name Stack to 30-99m Sub-Twmpau status is due to LIDAR analysis conducted by Myrddyn Phillips. The LIDAR (Light Detection & Ranging) technique produced highly accurate height data that is now freely available for much of England and Wales.
 |
| LIDAR image of the bwlch of No Name Stack |
 |
| LIDAR image of the summit of No Name Stack |
The 2m DSM LIDAR analysis gives the hill the following details:
Name: No Name Stack
Summit Height: 31.1m
Summit Grid Reference: SR 97567 93273
Bwlch Height: 2.6m
Bwlch Grid Reference: SR 97553 93308
Drop: 28.5m
Therefore, the 31.1m LIDAR analysis for the summit position at SR 97567 93273 and the 2.6m LIDAR analysis for the bwlch position at SR 97553 93308 gives this hill 28.5m of drop, which is insufficient for continued 30-99m Twmpau status.
 |
| LIDAR image of No Name Stack |
The full details for the hill are:
Group: Brandy Hill
Name: No Name Stack
OS 1:50,000 map: 158
Summit Height: 31.1m (LIDAR)
Summit Grid Reference: SR 97567 93273 (LIDAR)
Bwlch Height: 2.6m (LIDAR)
Bwlch Grid Reference: SR 97553 93308 (LIDAR)
Drop: 28.5m (LIDAR)
Myrddyn Phillips (September 2018)
Mapping Mountains - Hill Reclassifications - 30-99m Twmpau
Ynys Gyffylog (SH 629 138) – Double Sub-Twmpau addition (29th reclassification)
Survey post for Ynys Gyffylog
There has been confirmation of an addition to the 30-99m Twmpau list due to LIDAR analysis conducted by Myrddyn Phillips and subsequently confirmed via a survey with the Trimble GeoXH 6000, with the criteria for this list being:
30-99m Twmpau - Welsh hills at or above 30m and below 100m in height with 30m minimum drop, this height band of hills has two accompanying sub lists, the first of which is entitled the 30-99m Sub-Twmpau with the criteria for this sub category being all Welsh hills at or above 30m and below 100m in height with 20m or more and below 30m of drop, and the second sub category which this hill is a part of is entitled the Double Sub-Twmpau with the criteria for this sub category being all Welsh hills at or above 20m and below 30m in height with 20m or more and below 30m of drop, with the word Twmpau being an acronym standing for thirty welsh metre prominences and upward.
This hill did not appear in the accompanying Hills to be surveyed sub list when the original Welsh P30 hills were published on Geoff Crowder’s v-g.me website, as it did not meet the criteria then used for this sub category, however this sub list has now been standardised including the addition of interpolated drop values and interpolated summit heights.
This hill was included as a Double Sub-Twmpau after the Ordnance Survey Interactive Coverage Map became available on the Geograph website, and prior to LIDAR analysis it was listed with an estimated c 20m of drop based on the 23m summit spot height that appears on this map and an estimated bwlch height of c 3m based on interpolation of bwlch contouring between 0 – 10m.
 |
| Extract from the Ordnance Survey Interactive Coverage Map hosted on the Geograph website |
The name of the hill is Ynys Gyffylog and as its name implies it has association with being an island, or more strictly speaking a tidal estuary island that is now landlocked due to sea defences. The hill is adjoined to the Cadair Idris group of hills, which are situated in the south-western part of North Wales (Region A, Sub-Region A3), with the hill positioned beside the Arthog Bog and immediately behind a row of terraced houses, and has the Morfa Mawddach Station towards its north-west, the A 493 road to its south and the village of Y Friog (Fairbourne) to its south-west.
 |
| Ynys Gyffylog (SH 629 138) |
If wanting to visit the hill permission to do so should be sought as it is not a part of designated open access land, for those wishing to do so it can be a rough experience, especially so in summer as it has copious amounts of undergrowth.
The confirmation of the addition of Ynys Gyffylog to Double Sub-Twmpau status is due to LIDAR analysis conducted by Myrddyn Phillips. The LIDAR (Light Detection & Ranging) technique produced highly accurate height data that is now freely available for much of England and Wales.
 |
| LIDAR image of Ynys Gyffylog |
The 2m DTM LIDAR analysis gives the hill the following details:
Name: Ynys Gyffylog
Summit Height: 22.9m
Summit Grid Reference: SH 62965 13851
Bwlch Height: 2.4m
Bwlch Grid Reference: SH 63071 13758
Drop: 20.4m
Therefore, the 22.9m LIDAR analysis for the summit position at SH 62965 13851 and the 2.4m LIDAR analysis for the bwlch position at SH 63071 13758 gives this hill 20.4m of drop, with the details from the Trimble GeoXH 6000 survey being 23.1m (converted to OSGM15) summit height at SH 62964 13848, and when coupled with the LIDAR bwlch height it gives this hill 20.6m of drop, which confirms its addition to Double Sub-Twmpau status.
 |
| Somewhere amongst the undergrowth is the Trimble GeoXH 6000 gathering data at the summit of Ynys Gyffylog |
Group: Cadair Idris
Name: Ynys Gyffylog
OS 1:50,000 map: 124
Summit Height: 23.1m (converted to OSGM15)
Summit Grid Reference: SH 62964 13848
Bwlch Height: 2.4m (LIDAR)
Bwlch Grid Reference: SH 63071 13758 (LIDAR)
Drop: 20.6m (Trimble summit and LIDAR bwlch)
 |
| The Trimble set-up position at the summit of Ynys Gyffylog |
Myrddyn Phillips (September 2018)
Mapping Mountains - Hill Reclassifications - 30-99m Twmpau
Ynys Deullyn (SM 844 340) – 30-99m Twmpau addition (28th reclassification)
Significant Height Revisions post for Ynys Deullyn
There has been confirmation of an addition to the 30-99m Twmpau list due to LIDAR analysis conducted by Myrddyn Phillips, with the criteria for this list being:
30-99m Twmpau - Welsh hills at or above 30m and below 100m in height with 30m minimum drop, with an accompanying sub list entitled the 30-99m Sub-Twmpau with the criteria for this sub category being all Welsh hills at or above 30m and below 100m in height with 20m or more and below 30m of drop, with the word Twmpau being an acronym standing for thirty welsh metre prominences and upward.
This hill did not appear in the main P30 list or the accompanying Hills to be surveyed sub list when the original Welsh P30 hills were published on Geoff Crowder’s v-g.me website, as it was thought not to have 30m of drop and did not meet the criteria then used for the sub category; however this sub list has now been standardised including the addition of interpolated drop values and heights.
This hill was included as a P30 shortly after the Ordnance Survey Interactive Coverage Map became available on the Geograph website, and prior to LIDAR analysis it was listed with 30m of drop based on the 30m summit spot height that appears on this map.
 |
| 2m DTM LIDAR image of Ynys Deullyn (SM 844 340) |
The name of the hill is Ynys Deullyn and as its name implies it is an island, or more strictly speaking a tidal island that is attached to mainland Wales at low tide. The hill is adjoined to the Carn Llidi group of hills, which are situated in the south-western part of Mid and West Wales (Region B, Sub-Region B4), with the island being positioned on the northern part of the Pembrokeshire coast, and has the small community of Abercastell towards its west south-west.
If wanting to visit the island permission to do so should be sought as it is not a part of designated open access land, for those wishing to do so caution is advised as the easiest approach will probably necessitate some form of scramble.
The confirmation of the addition of Ynys Deullyn to 30-99m Twmpau status is due to LIDAR analysis conducted by Myrddyn Phillips. The LIDAR (Light Detection & Ranging) technique produced highly accurate height data that is now freely available for much of England and Wales.
The 2m DSM LIDAR analysis gives the hill the following details:
Name: Ynys Deullyn
Summit Height: 32.6m
Summit Grid Reference: SM 84479 34095
Bwlch Height: 2.1m
Bwlch Grid Reference: SM 84513 34087
Drop: 30.5m
 |
| 2m DSM LIDAR image of Ynys Deullyn (SM 844 340) |
Therefore, the 32.6m LIDAR analysis for the summit position at SM 84479 34095 and the 2.1m LIDAR analysis for the bwlch position at SM 84513 34087 gives this hill 30.5m of drop, which is sufficient for 30-99m Twmpau status.
The full details for the hill are:
Group: Carn Llidi
Name: Ynys Deullyn
OS 1:50,000 map: 157
Summit Height: 32.6m (LIDAR)
Summit Grid Reference: SM 84479 34095 (LIDAR)
Bwlch Height: 2.1m (LIDAR)
Bwlch Grid Reference: SM 84513 34087 (LIDAR)
Drop: 30.5m (LIDAR)
Myrddyn Phillips (September 2018)
Mapping Mountains - Hill Reclassifications - 30-99m Twmpau
Gewni (SM 796 236) – 30-99m Twmpau addition (27th reclassification)
There has been confirmation of an addition to the 30-99m Twmpau list due to LIDAR analysis conducted by Myrddyn Phillips, with the criteria for this list being:
30-99m Twmpau - Welsh hills at or above 30m and below 100m in height with 30m minimum drop, with an accompanying sub list entitled the 30-99m Sub-Twmpau with the criteria for this sub category being all Welsh hills at or above 30m and below 100m in height with 20m or more and below 30m of drop, with the word Twmpau being an acronym standing for thirty welsh metre prominences and upward.
This hill did not appear in the main P30 list or the accompanying Hills to be surveyed sub list when the original Welsh P30 hills were published on Geoff Crowder’s v-g.me website as it was thought not to have 30m of drop and did not meet the criteria then used for the sub category; however this sub list has now been standardised including the addition of interpolated drop values and heights.
This hill was included as a P30 shortly after the Ordnance Survey Interactive Coverage Map became available on the Geograph website, and prior to LIDAR analysis it was listed with 35m of drop based on the 35m summit spot height that appears on this map.
The name of the hill is Gewni and it is a tidal island that is attached to mainland Wales at low tide. The hill is adjoined to the Carn Llidi group of hills, which are situated in the south-western part of Mid and West Wales (Region B, Sub-Region B4), with the island being positioned to the west of where the Afon Solfach (River Solva) enters the sea, and has the village of Solfach (Solva) towards its north-east.
 |
| Gewni (SM 796 236) |
If wanting to visit the hill it is a part of designated open access land, for those wishing to do so caution is advised as the easiest approach will probably necessitate some form of scramble.
The confirmation of the addition of Gewni to 30-99m Twmpau status is due to LIDAR analysis conducted by Myrddyn Phillips. The LIDAR (Light Detection & Ranging) technique produced highly accurate height data that is now freely available for much of England and Wales.
The 1m DTM LIDAR analysis gives the hill the following details:
Name: Gewni
Summit Height: 35.7m
Summit Grid Reference: SM 79696 23606
Bwlch Height: 0.3m
Bwlch Grid Reference: SM 79689 23698
Drop: 35.3m
 |
| LIDAR image of Gewni |
Therefore, the 35.65m LIDAR analysis for the summit position at SM 79696 23606 and the 0.3m LIDAR analysis for the bwlch position at SM 79689 23698 gives this hill 35.3m of drop, which is sufficient for 30-99m Twmpau status.
The full details for the hill are:
Group: Carn Llidi
Name: Gewni
OS 1:50,000 map: 157
Summit Height: 35.7m (LIDAR)
Summit Grid Reference: SM 79696 23606 (LIDAR)
Bwlch Height: 0.3m (LIDAR)
Bwlch Grid Reference: SM 79689 23698 (LIDAR)
Drop: 35.3m (LIDAR)
Myrddyn Phillips (August 2018)
Mapping Mountains - Hill Reclassifications - 30-99m Twmpau
Ynys Ddu (SM 886 388) – 30-99m Twmpau addition (26th reclassification)
There has been confirmation of an addition to the 30-99m Twmpau list due to LIDAR analysis conducted by Myrddyn Phillips, with the criteria for this list being:
30-99m Twmpau - Welsh hills at or above 30m and below 100m in height with 30m minimum drop, with an accompanying sub list entitled the 30-99m Sub-Twmpau with the criteria for this sub category being all Welsh hills at or above 30m and below 100m in height with 20m or more and below 30m of drop, with the word Twmpau being an acronym standing for thirty welsh metre prominences and upward.
This hill did not appear in the main P30 list or the accompanying Hills to be surveyed sub list when the original Welsh P30 hills were published on Geoff Crowder’s v-g.me website as it was thought not to have 30m of drop and did not meet the criteria then used for the sub category; however this sub list has now been standardised including the addition of interpolated drop values and heights.
 |
| Ynys Ddu (SM 886 388). Photo: Jon Glew |
It was Mick Moore who brought the attention of this hill’s P30 status to the hill bagging community and prior to LIDAR analysis the hill was listed with an estimated summit height of c 32m based on a small 30m uppermost contour ring on Ordnance Survey 1:25,000 Explorer maps.
The name of the hill is Ynys Ddu and as its name implies it is an island, or more strictly speaking a tidal island that is attached to mainland Wales at low tide. The hill is adjoined to the Mynydd Preseli group of hills, which are situated in the south-western part of Mid and West Wales (Region B, Sub-Region B4), with the island being positioned on the western part of Pen-caer (Stumble Head), and has the town of Abergwaun (Fishguard) towards the east south-east.
 |
| The summit of Ynys Ddu. Photo: Jon Glew |
If wanting to visit the hill permission to do so should be sought as it is not a part of designated open access land, for those wishing to do so caution is advised as the easiest approach will probably necessitate a scramble.
The confirmation of the addition of Ynys Ddu to 30-99m Twmpau status is due to LIDAR analysis conducted by Myrddyn Phillips. The LIDAR (Light Detection & Ranging) technique produced highly accurate height data that is now freely available for much of England and Wales.
The 2m DSM LIDAR analysis gives the hill the following details:
Ynys Ddu
Summit Height: 31.9m
Summit Grid Reference: SM 88673 38869
Bwlch Height: 0.5m
Bwlch Grid Reference: SM 88721 38853
Drop: 31.3m
 |
| LIDAR image of Ynys Ddu |
Therefore, the 31.9m LIDAR analysis for the summit position at SM 88673 38869 and the 0.5m LIDAR analysis for the bwlch position at SM 88721 38853 gives this hill 31.3m of drop, which is sufficient for 30-99m Twmpau status.
The full details for the hill are:
Group: Mynydd Preseli
Name: Ynys Ddu
OS 1:50,000 map: 157
Summit Height: 31.9m (LIDAR)
Summit Grid Reference: SM 88673 38869 (LIDAR)
Bwlch Height: 0.5m (LIDAR)
Bwlch Grid Reference: SM 88721 38853 (LIDAR)
Drop: 31.3m (LIDAR)
My thanks to Jon Glew for permission to reproduce his photos of Ynys Ddu
Myrddyn Phillips (July 2018)
Myrddyn Phillips (July 2018)
Mapping Mountains - Hill Reclassifications - 30-99m Twmpau
Fegla Fach (SH 638 153) – Double Sub-Twmpau reclassified to 30-99m Twmpau (25th reclassification)
Survey post for Fegla Fach
Significant Height Revisions post for Fegla Fach
There has been a reclassification to the 30-99m Twmpau list due to LIDAR analysis, an on-site visit and a survey with the Trimble GeoXH 6000 which took place on the 17th May 2018, with the criteria for this list being:
30-99m Twmpau - Welsh hills at or above 30m and below 100m in height with 30m minimum drop, this height band of hills has two accompanying sub lists, the first of which is entitled the 30-99m Sub-Twmpau with the criteria for this sub category being all Welsh hills at or above 30m and below 100m in height with 20m or more and below 30m of drop, and the second sub category which this hill is a part of is entitled the Double Sub-Twmpau with the criteria for this sub category being all Welsh hills at or above 20m and below 30m in height with 20m or more and below 30m of drop, with the word Twmpau being an acronym standing for thirty welsh metre prominences and upward.
This hill did not appear in the accompanying Hills to be surveyed sub list when the original Welsh P30 hills were published on Geoff Crowder’s v-g.me website as it did not meet the criteria for this sub category; however this sub list has now been standardised including the addition of interpolated drop values and heights.
This hill did not appear in the accompanying Hills to be surveyed sub list when the original Welsh P30 hills were published on Geoff Crowder’s v-g.me website as it did not meet the criteria for this sub category; however this sub list has now been standardised including the addition of interpolated drop values and heights.
Prior to LIDAR analysis, an on-site visit and the Trimble GeoXH 6000 survey this hill was listed with 25m of drop based on the 28m summit spot height that appears on the Ordnance Survey 1:25,000 Explorer map and the 3m spot height that appears on the area of this hill’s bwlch on the Ordnance Survey Interactive Coverage Map hosted on the Geograph website.
 |
| Extract from the Ordnance Survey Interactive Coverage Map hosted on the Geograph website |
The name of the hill is Fegla Fach and it is adjoined to the Cadair Idris group of hills, which are situated in the south-western part of North Wales (Region A, Sub-Region A3), with the hill being positioned between the Afon Mawddach to its west and north and the A 493 road to its south-east, and has the village of Y Friog (Fairbourne) to the south-west.
 |
| Fegla Fach from across the Afon Mawddach |
 |
| Fegla Fach from its connecting bwlch |
If wanting to visit the hill permission to do so should be sought as it is not a part of designated open access land, for those wishing to do so the minor road to the south of the hill joins a public footpath that then heads toward it.
The addition of Fegla Fach to 30-99m Twmpau status is in part due to LIDAR analysis conducted by Myrddyn Phillips. The LIDAR (Light Detection & Ranging) technique produced highly accurate height data that is now freely available for much of England and Wales.
The 1m DTM LIDAR analysis gives the hill the following details:
Fegla Fach
Summit Height: 31.5m
Summit Grid Reference: SH 63818 15311
Bwlch Height: 1.6m
Bwlch Grid Reference: SH 63691 15131 and SH 69693 15130
Drop: 29.9m
This hill and others in the vicinity used to be tidal islands before sea defences were constructed, with the Afon Mawddach positioned to the immediate north, west and east of the hill, this has resulted in this hill now being landlocked by its connecting bwlch which is a part of the larger Arthog Bog.
The area of the connecting bwlch of this hill is complicated to analyse via LIDAR as it is low lying and the land has been terraformed with embankments and drainage ditches. However, extensive LIDAR analysis pinpoints the position of what can be construed as this hill’s remaining natural bwlch to be on or just below what is now a small land bridge.
 |
| LIDAR image of Fegla Fach (top right corner) and the land making up the Arthog Bog |
This land bridge crosses one of many drainage ditches in the Arthog Bog and this position was surveyed using the Trimble GeoXH 6000, with three measurement offsets noted, the first to ground making up the land bridge, the second to water level in the drainage ditch and the third to ground mid-way between the land bridge and the water level, the survey results appear below:
1st survey, land bridge: 1.577m
2nd survey, water level in drainage ditch: 1.337m
3rd survey, mid-point between land bridge and water level: 1.457m
 |
| The Trimble GeoXH 6000 gathering data at the bwlch of Fegla Fach |
When these survey results are combined with the LIDAR result for the summit of this hill the drop values for each of the three points at the bwlch are:
1st survey, land bridge: 29.912m
2nd survey, water level in drainage ditch: 30.152m
3rd survey, mid-point between land bridge and water level: 30.032m
The summit of this hill was analysed using the 1m DTM LIDAR model and as the high point consists of a large rock with a number of trees growing directly beside it, it is probable that the LIDAR technique did not model the very highest part of this rock, and when coupled with the result produced by the Trimble bwlch survey it is deemed sufficient to list this hill with a drop value of 30m, which is sufficient for 30-99m Twmpau status.
 |
| The summit of Fegla Fach |
The full details for the hill are:
Group: Cadair Idris
Name: Fegla Fach
Summit Height: 31.5m (LIDAR)
Summit Grid Reference: SH 63818 15311 (LIDAR)
Bwlch Height: 1.5m (converted to OSGM15)
Bwlch Grid Reference: SH 63692 15129
OS 1:50,000 map: 124
Drop: 30.0m (LIDAR summit and Trimble bwlch)
Myrddyn Phillips (July 2018)
Mapping Mountains - Hill Reclassifications - 30-99m Twmpau
Coed Abergwynant (SH 681 179) – 30-99m Sub-Twmpau addition (24th reclassification)
There has been an addition to the 30-99m Twmpau list due to LIDAR analysis conducted by Myrddyn Phillips, with the criteria for this list being:
30-99m Twmpau - Welsh hills at or above 30m and below 100m in height with 30m minimum drop, with an accompanying sub list entitled the 30-99m Sub-Twmpau with the criteria for this sub category being all Welsh hills at or above 30m and below 100m in height with 20m or more and below 30m of drop, with the word Twmpau being an acronym standing for thirty welsh metre prominences and upward.
This hill did not appear in the accompanying Hills to be surveyed sub list when the original Welsh P30 hills were published on Geoff Crowder’s v-g.me website as it did not meet the criteria for this sub category; however this sub list has now been standardised including the addition of interpolated drop values and heights.
Prior to LIDAR analysis this hill was listed with an estimated c 19m of drop based on an estimated c 93m summit height based on interpolation of the uppermost 90m ring contour and an estimated bwlch height of c 74m based on interpolation of bwlch contouring between 70m – 80m on the Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer map.
 |
| Extract from the Ordnance Survey Interactive Coverage Map hosted on the Geograph website |
The hill takes its listed name from the wood that its summit is situated in; Coed Abergwynant, and it is adjoined to the Cadair Idris group of hills, which are situated in the south-western part of North Wales (Region A, Sub-Region A3), with the hill being positioned between the Afon Mawddach to the north-west and the A 493 road to the south-east, and has the town of Dolgellau towards its east.
If wanting to visit the hill permission to do so should be sought as it is not a part of designated open access land, for those wishing to do so the nearest convenient access point is the A 493 road and a track to the east of the summit.
The addition of Coed Abergwynant to 30-99m Sub-Twmpau status is due to LIDAR analysis conducted by Myrddyn Phillips. The LIDAR (Light Detection & Ranging) technique produced highly accurate height data that is now freely available for much of England and Wales.
The 1m DTM LIDAR analysis gives the hill the following details:
Coed Abergwynant
Summit Height: 91.0m
Summit Grid Reference: SH 68136 17938
Bwlch Height: 69.5m
Bwlch Grid Reference: SH 67827 17866
Drop: 21.5m
 |
| LIDAR image of Coed Abergwynant |
Therefore, the 91.0m LIDAR analysis for the summit position at SH 68136 17938 and the 69.5m LIDAR analysis for the bwlch position at SH 67827 17866 gives this hill 21.5m of drop, which is sufficient for 30-99m Sub-Twmpau status.
The full details for the hill are:
Group: Cadair Idris
Name: Coed Abergwynant
Summit Height: 91.0m (LIDAR)
Summit Grid Reference: SH 68136 17938 (LIDAR)
OS 1:50,000 map: 124
Drop: 21.5m (LIDAR)
Myrddyn Phillips (June 2018)
Mapping Mountains - Hill Reclassifications - 30-99m Twmpau
Cae Benglog (SH 316 380) – 30-99m Sub-Twmpau addition (23rd reclassification)
Summit Relocations post for Cae Benglog
Significant Name Changes post for Cae Benglog
There has been an addition to the 30-99m Twmpau due to LIDAR analysis conducted by Myrddyn Phillips, with the criteria for this list being:
30-99m Twmpau - Welsh hills at and above 30m and below 100m in height with 30m minimum drop, with an accompanying sub list entitled the 30-99m Sub-Twmpau with the criteria for this sub category being all Welsh hills at and above 30m and below 100m in height with 20m and more and below 30m of drop, with the word Twmpau being an acronym standing for thirty welsh metre prominences and upward.
This hill did not appear in the accompanying Hills to be surveyed sub list when the original Welsh P30 hills were published on Geoff Crowder’s v-g.me website as it did not meet the criteria for this sub category; however this sub list has now been standardised including the addition of interpolated drop values and heights.
Prior to LIDAR analysis this hill was listed with an estimated c 19m of drop based on the 86m spot height positioned at SH 31361 38368 on the Ordnance Survey 1:25,000 Explorer map and an estimated bwlch height of c 67m based on bwlch contouring at 5m intervals and between 65m – 70m on the Ordnance Survey Interactive Coverage Map hosted on the Geograph website.
 |
| Extract from the Ordnance Survey 1:25,000 Explorer map |
The name of the bounded land where the summit of this hill is situated is Cae Benglog with these details derived from the Tithe map and the hill is adjoined to the Pen Llŷn group of hills, which is situated in the north-west part of North Wales (Region A, Sub-Region A1), and is positioned overlooking the A 497 road which is to its north-east and has the small community of Morfa Nefyn t0 its north-west and the town of Pwllheli towards the south-east.
If wanting to visit the hill permission to do so should be sought as it is not a part of designated open access land, with the nearest public footpath close to the summit to its east.
The addition of Cae Benglog to 30-99m Sub-Twmpau status is due to LIDAR analysis conducted by Myrddyn Phillips. The LIDAR (Light Detection & Ranging) technique produced highly accurate height data that is now freely available for much of England and Wales.
LIDAR analysis gives the hill the following details:
Cae Benglog
Summit Height: 86.8m
Summit Grid Reference: SH 31635 38073
Bwlch Height: 65.9m
Bwlch Grid Reference: SH 31523 38448
Drop: 20.9m
 |
| LIDAR image of Cae Benglog |
Therefore, the 86.779m LIDAR analysis for the summit position at SH 31635 38073 and the 65.873m LIDAR analysis for the bwlch position at SH 31523 38448 gives this hill 20.906m of drop, which is sufficient for 30-99m Sub-Twmpau status.
A point to the north-west of this summit and which is given an 86m spot height on the Ordnance Survey 1:25,000 Explorer map was also examined via LIDAR, resulting in a 85.355m height positioned at SH 31355 38373.
The full details for the hill are:
Group: Pen Llŷn
Name: Cae Benglog
Summit Height: 86.8m (LIDAR)
Summit Grid Reference: SH 31635 38073 (LIDAR)
OS 1:50,000 map: 123
Drop: 20.9m (LIDAR)
Myrddyn Phillips (April 2018)
Mapping Mountains - Hill Reclassifications - 30-99m Twmpau
Allt Fawr (SH 383 356) – 30-99m Sub-Twmpau addition (22nd reclassification)
Significant Height Revisions post for Allt Fawr
Summit Relocations post for Allt Fawr
There has been an addition to the 30-99m Twmpau due to LIDAR analysis conducted by Myrddyn Phillips, with the criteria for this list being:
30-99m Twmpau - Welsh hills at and above 30m and below 100m in height with 30m minimum drop, with an accompanying sub list entitled the 30-99m Sub-Twmpau with the criteria for this sub category being all Welsh hills at and above 30m and below 100m in height with 20m and more and below 30m of drop, with the word Twmpau being an acronym standing for thirty welsh metre prominences and upward.
This hill did not appear in the accompanying Hills to be surveyed sub list when the original Welsh P30 hills were published on Geoff Crowder’s v-g.me website as it did not meet the criteria for this sub category; however this sub list has now been standardised and interpolated heights also included.
Prior to LIDAR analysis this hill was listed with an estimated c 18m of drop based on an estimated summit height of c 46m with the hill being given three uppermost 45m ring contours on the Ordnance Survey Interactive Coverage Map hosted on the Geograph website and an estimated bwlch height of c 28m based on bwlch contouring at 5m intervals and between 25m – 30m on this same map.
 |
| Extract from the Ordnance Survey Interactive Coverage Map hosted on the Geograph website |
The name of the hill is Allt Fawr and it is adjoined to the Pen Llŷn group of hills, which is situated in the north-west part of North Wales (Region A, Sub-Region A1), and is positioned with the A 499 and the A 497 roads to its west and east respectively and has the town of Pwllheli towards the south-west.
If wanting to visit the hill permission to do so should be sought as it is not a part of designated open access land and does not have any rights of way on it.
The addition of Allt Fawr to 30-99m Sub-Twmpau status is due to LIDAR analysis conducted by Myrddyn Phillips. The LIDAR (Light Detection & Ranging) technique produced highly accurate height data that is now freely available for much of England and Wales.
LIDAR analysis gives the hill the following details:
Allt Fawr
Summit Height: 48.9m
Summit Grid Reference: SH 38347 35695
Bwlch Height: 25.8m
Bwlch Grid Reference: SH 38411 35961
Drop: 23.1m
 |
| LIDAR image of Allt Fawr |
Therefore, the 48.889 LIDAR analysis for the summit position at SH 38347 35695 and the 25.753m LIDAR analysis for the bwlch position at SH 38411 35961 gives this hill 23.136m of drop, which is sufficient for 30-99m Sub-Twmpau status.
Three other tops were also analysed by LIDAR on the hill of Allt Fawr, resulting in the following; 46.569m at SH 38145 35521, 44.962m at SH 38406 35898 and 44.944m at SH 38383 35833.
The full details for the hill are:
Group: Pen Llŷn
Name: Allt Fawr
Summit Height: 48.9m (LIDAR)
Summit Grid Reference: SH 38347 35695 (LIDAR)
OS 1:50,000 map: 123
Drop: 23.1m (LIDAR)
Myrddyn Phillips (April 2018)
Mapping Mountains - Hill Reclassifications - 30-99m Twmpau
Carreg y Defaid (SH 341 325) – 30-99m Sub-Twmpau deletion (21st reclassification)
There has been a deletion to the 30-99m Twmpau due to LIDAR analysis conducted by Myrddyn Phillips, with the criteria for this list being:
30-99m Twmpau - Welsh hills at and above 30m and below 100m in height with 30m minimum drop, with an accompanying sub list entitled the 30-99m Sub-Twmpau with the criteria for this sub category being all Welsh hills at and above 30m and below 100m in height with 20m and more and below 30m of drop, with the word Twmpau being an acronym standing for thirty welsh metre prominences and upward.
This hill did not appear in the accompanying Hills to be surveyed sub list when the original Welsh P30 hills were published on Geoff Crowder’s v-g.me website as it did not meet the criteria for this sub category; however this sub list has now been standardised and interpolated heights also included.
Prior to LIDAR analysis this hill was listed with an estimated c 20m of drop based on the 33m summit spot height that appears on the Ordnance Survey 1:25,000 Explorer map and an estimated bwlch height of c 13m based on bwlch contouring at 5m intervals and between 10m – 15m on the Ordnance Survey Interactive Coverage Map hosted on the Geograph website.
 |
| Extract from the Ordnance Survey Interactive Coverage Map hosted on the Geograph website |
The name of the hill is Carreg y Defaid and it is adjoined to the Pen Llŷn group of hills, which is situated in the north-west part of North Wales (Region A, Sub-Region A1), and is positioned with the A 499 road to its west and between the village of Llanbedrog to the south-west and the town of Pwllheli towards the north-west.
If wanting to visit the hill permission to do so should be sought as it is not a part of designated open access land, for those wishing to do so the Wales Coast Path passes close to its summit and would give easiest access.
The deletion of Carreg y Defaid from 30-99m Sub-Twmpau status is due to LIDAR analysis conducted by Myrddyn Phillips. The LIDAR (Light Detection & Ranging) technique produced highly accurate height data that is now freely available for much of England and Wales.
LIDAR analysis gives the hill the following details:
Carreg y Defaid
Summit Height: 33.4m
Summit Grid Reference: SH 34109 32555
Bwlch Height: 13.7m (natural bwlch)
Bwlch Grid Reference: SH 33751 32623 (natural bwlch)
Drop: 19.7m
 |
| LIDAR image of Craig y Defaid |
Therefore, the 33.389m LIDAR analysis for the summit position at SH 34109 32555 and the 13.693m LIDAR analysis for the bwlch position at SH 33751 32623 gives this hill 19.696m of drop, which is insufficient for 30-99m Sub-Twmpau status.
There is a 13.747m higher hill to hill traverse positioned at SH 33818 32605, but as this is to an elevated road which is considered man-made the remaining natural bwlch is being taken for the drop value of this hill.
The full details for the hill are:
Group: Pen Llŷn
Name: Carreg y Defaid
Summit Height: 33.4m (LIDAR)
Summit Grid Reference: SH 34109 32555 (LIDAR)
OS 1:50,000 map: 123
Drop: 19.7m (LIDAR)
Myrddyn Phillips (April 2018)
Mapping Mountains - Hill Reclassifications - 30-99m Twmpau
Rhiw Tir (SH 601 451) – 30-99m Sub-Twmpau addition (20th reclassification)
There has been an addition to the listing of the 30-99m Twmpau (thirty welsh metre prominences and upward) due to analysis conducted by Aled Williams of data produced via LIDAR. The 30-99m Twmpau is the title for the list of Welsh hills at and above 30m and below 100m in height that have a minimum 30m of drop.
Accompanying the main Twmpau list is a sub list entitled the Sub-Twmpau, with this hill being added to the 30-99m Sub-Twmpau category. The criteria for 30-99m Sub-Twmpau status being all Welsh hills at and above 30m and below 100m in height with 20m or more and below 30m of drop.
Prior to analysis of data produced via LIDAR this hill was not listed in the Hills to be surveyed sub list that accompanied the Welsh P30 lists published on Geoff Crowder’s v-g.me website. When these lists were re-evaluated after they were standardised and also drop values added, this hill was listed with c 19m of drop based on the 54m summit spot height that appears on the Ordnance Survey Interactive Coverage Map hosted on the Geograph website and an estimated bwlch height of c 35m based on 10m contour intervals between 30m – 40m.
The name of the hill is Rhiw Tir and it is situated in the Moelwynion range of hills and is placed in the Region of North Wales (Region A, Sub-Region A1). The hill is positioned with the Welsh Highland Railway and the A 498 road to its west and the A 4085 road to its north and east, and has the village of Beddgelert to its north north-west and the town of Porthmadog to its south south-west.
As the hill is not a part of designated open access land permission to visit should be sought, however the hill has a well-used path leading through the deciduous wood that takes in its summit indicating that people have visited this area for many years.
The addition of Rhiw Tir to 30-99m Sub-Twmpau status is due to analysis conducted by Aled Williams of data produced via LIDAR. The LIDAR (Light Detection & Ranging) technique produced highly accurate height data that is now freely available for much of England and Wales.
Aled’s analysis of the data produced via LIDAR gives the hill the following details:
Rhiw Tir
Summit Height: 54.4m
Summit Grid Reference: SH 60112 45108
Bwlch Height: 31.3m
Bwlch Grid Reference: SH 60060 44996
Drop: 23.1m
Therefore, the 54.4m data produced via LIDAR for the summit position at SH 60112 45108 and the 31.3m data produced via LIDAR for the bwlch position at SH 60060 44996 gives this hill 23.1m of drop, which is sufficient for its inclusion as a 30-99m Sub-Twmpau.
The full details for the hill are:
Group: Moelwynion
Summit Height: 54.4m (data via LIDAR)
Name: Rhiw Tir
OS 1:50,000 map: 115
Summit Grid Reference: SH 60112 45108
Drop: 23.1m (data via LIDAR)
My thanks to Aled Williams for sending the details of this hill to me
Myrddyn Phillips (February 2018)
Mapping Mountains - Hill Reclassifications - 30-99m Twmpau
Pt. 47.8m (SH 604 438) – 30-99m Sub-Twmpau addition (19th reclassification)
There has been an addition to the listing of the 30-99m Twmpau (thirty welsh metre prominences and upward) due to analysis conducted by Aled Williams of data produced via LIDAR. The 30-99m Twmpau is the title for the list of Welsh hills at and above 30m and below 100m in height that have a minimum 30m of drop.
Accompanying the main Twmpau list is a sub list entitled the Sub-Twmpau, with this hill being added to the 30-99m Sub-Twmpau category. The criteria for 30-99m Sub-Twmpau status being all Welsh hills at and above 30m and below 100m in height with 20m or more and below 30m of drop.
Prior to analysis of data produced via LIDAR this hill was not listed in the Hills to be surveyed sub list that accompanied the Welsh P30 lists published on Geoff Crowder’s v-g.me website. When these lists were re-evaluated after they were standardised and also drop values added, this hill was listed with c 20m of drop based on the 46m summit spot height that appears on the Ordnance Survey 1:25,000 Explorer map and an estimated bwlch height of c 26m based on 10m contour intervals between 20m – 30m.
As I do not know a separate and independent name for this hill it is being listed by the point (Pt. 47.8m) notation, and it is situated in the Moelwynion range of hills and is placed in the Region of North Wales (Region A, Sub-Region A1). The hill is positioned with the Welsh Highland Railway and the A 498 road to its west and the A 4085 road to its east, and has the village of Beddgelert to its north- north-west and the town of Porthmadog towards its south-west.
As the hill is not a part of designated open access land permission to visit should be sought, however the hill has a well-used path leading through the deciduous wood that takes in its summit indicating that people have visited this area for many years.
The addition of Pt. 47.8m to 30-99m Sub-Twmpau status is due to analysis conducted by Aled Williams of data produced via LIDAR. The LIDAR (Light Detection & Ranging) technique produced highly accurate height data that is now freely available for much of England and Wales.
Aled’s analysis of the data produced via LIDAR gives the hill the following details:
Pt. 47.8m
Summit Height: 47.8m
Summit Grid Reference: SH 60404 43809
Bwlch Height: 24.0m
Bwlch Grid Reference: SH 60344 43884
Drop: 23.8m
Therefore, the 47.8m data produced via LIDAR for the summit position at SH 60404 43809 and the 24.0m data produced via LIDAR for the bwlch position at SH 60344 43884 gives this hill 23.8m of drop, which is sufficient for its inclusion as a 30-99m Sub-Twmpau.
The full details for the hill are:
Group: Moelwynion
Summit Height: 47.8m (data via LIDAR)
Name: Pt. 47.8m
OS 1:50,000 map: 124
Summit Grid Reference: SH 60404 43809
Drop: 23.8m (data via LIDAR)
My thanks to Aled Williams for sending the details of this hill to me
Myrddyn Phillips (February 2018)
Mapping Mountains - Hill Reclassifications - 30-99m Twmpau
Bryn y Bont (SH 596 459) – Double Sub-Twmpau addition (18th reclassification)
Significant Height Revisions post for Bryn y Bont
Summit Relocations post for Bryn y Bont
There has been an addition to the listing of the Double Sub-Twmpau due to analysis conducted by Aled Williams of data produced via LIDAR. With the title of Twmpau being an acronym for thirty welsh metre prominences and upward.
Accompanying each 100m height band within the main Twmpau list is a sub list entitled the Sub-Twmpau, with the Double Sub-Twmpau attached to the lower tier height band of Welsh hills.
The criteria for the lower tier of Twmpau hills are:
30-99m Twmpau – All Welsh hills at and above 30m and below 100m in height with 30m minimum drop.
30-99m Sub-Twmpau – All Welsh hills at and above 30m and below 100m in height with 20m or more and below 30m of drop.
Double Sub-Twmpau – All Welsh hills at and above 20m and below 30m in height with 20m or more and below 30m of drop.
Prior to analysis of data produced via LIDAR this hill was not listed in the Hills to be surveyed sub list that accompanied the Welsh P30 lists published on Geoff Crowder’s v-g.me website. When these lists were re-evaluated after they were standardised and also drop values added, this hill was listed with c 16m of drop based on an estimated c 20m summit height which was based on this hill’s small uppermost 20m ring contour on Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer maps, and an estimated bwlch height of c 4m based on bwlch contouring at 10m intervals and between 0 – 10m, with the caveat that the 4m spot height positioned at SH 59756 45814 and shown on the Ordnance Survey 1:25,000 Explorer map is probably not at the position of the critical bwlch.
The name of the hill is Bryn y Bont and it is situated in the Moelwynion range of hills and is placed in the Region of North Wales (Region A, Sub-Region A1). The hill is positioned with the A 4085 road to its north and its east and the A 498 road to its west, and has the Afon Glaslyn also to its immediate west, with the hamlet of Nantmor positioned to the east of the hill and the village of Beddgelert towards its north.
As the hill is not a part of designated open access land permission to visit should be sought, for those wishing to do so an ascent from the convenience of the road to its north or east is likely to be the easiest.
The addition of Bryn y Bont to Double Sub-Twmpau status is due to analysis conducted by Aled Williams of data produced via LIDAR. The LIDAR (Light Detection & Ranging) technique produced highly accurate height data that is now freely available for much of England and Wales.
Aled’s analysis of the data produced via LIDAR gives the hill the following details:
Bryn y Bont
Summit Height: 25.2m
Summit Grid Reference: SH 59641 45973
Bwlch Height: 4.3m
Bwlch Grid Reference: SH 59572 46137
Drop: 20.9m
Therefore, the 25.2m data produced via LIDAR for the summit position at SH 59641 45973 and the 4.3m data produced via LIDAR for the bwlch position at SH 59572 46137 gives this hill 20.9m of drop, which is sufficient for it to be classified as a Double Sub-Twmpau.
The full details for the hill are:
Group: Moelwynion
Summit Height: 25.2m (data via LIDAR)
Name: Bryn y Bont
OS 1:50,000 map: 115
Summit Grid Reference: SH 59641 45973
Drop: 20.9m (data via LIDAR)
My thanks to Aled Williams for sending the details of this hill to me
Mapping Mountains - Hill Reclassifications - 30-99m Twmpau
Bryn y Gwynt (SH 599 449) – 30-99m Sub-Twmpau reclassified to 30-99m Twmpau (17th reclassification)
Significant Name Changes post for Bryn y Gwynt
Significant Height Revisions post for Bryn y Gwynt
Summit Relocations post for Bryn y Gwynt
There has been a reclassification to a hill that is listed in the 30-99m Twmpau, with the summit height, bwlch height, their locations, the drop and status of the hill confirmed by LIDAR analysis conducted by Aled Williams and a subsequent Trimble GeoXH 6000 survey conducted by Myrddyn Phillips and Aled Williams.
 |
| LIDAR image of Bryn y Gwynt (SH 599 449) |
The criteria for the list that this reclassification applies to are:
30-99m Twmpau - Welsh hills at or above 30m and below 100m in height with 30m minimum drop, with an accompanying sub list entitled the 30-99m Sub-Twmpau with the criteria for this sub category being all Welsh hills at or above 30m and below 100m in height with 20m or more and below 30m of drop, with the word Twmpau being an acronym standing for thirty welsh metre prominences and upward.
The name the hill is listed by is Bryn y Gwynt and this was derived from local enquiry and the series of Ordnance Survey Six-Inch maps and it is situated in the Moelwynion range of hills in the Region of North Wales (Region A, Sub-Region A1), and is positioned with the A 4085 road to its north-east and has the Welsh Highland Railway to its immediate west and overlooks the Afon Glaslyn also to its west, and has the village of Beddgelert to its north north-west and the town of Porthmadog to its south south-west.
The hill is a part of Coed Hafod y Llyn, and as this name implies its summit is placed in woodland which is deciduous, and as the summit of the hill is not a part of designated open access land permission to visit should be sought, however paths are indicated on the map to the north, east and south of this hill’s summit and therefore gaining access to its lower slopes has probably been accepted for many years.
Prior to LIDAR analysis this hill was listed in the Hills to be surveyed sub list that accompanied the Welsh P30 lists published on Geoff Crowder’s v-g.me website. When these sub lists were standardised and also drop values added, this hill was listed with an estimated c 29m of drop based on the 56m spot height that appears on the Ordnance Survey 1:25,000 Explorer map at SH 59881 44828 and an estimated bwlch height of c 27m based on contouring at 10m intervals between 20m – 30m, with the caveat that the 27m spot height that appears on a road at SH 60168 45293 on the Ordnance Survey Interactive Coverage Map hosted on the Geograph website is judged not to be positioned at the critical bwlch.
However, it was not until LIDAR became available
that the details for this hill could be accurately re-assessed. The LIDAR (Light Detection & Ranging)
technique produced highly accurate height data that is now freely available for
much of England and Wales.
LIDAR analysis confirms this hill to be a 30-99m Twmpau, and as the summit has now been surveyed with the Trimble GeoXH 6000, it is this result that is being prioritised for listing purposes.
 |
| The Trimble GeoXH 6000 gathering data at the summit of Bryn y Gwynt |
Therefore, the reclassification of this hill from 30-99m Sub-Twmpau status is due to LIDAR analysis and a subsequent Trimble GeoXH 6000 survey, resulting in a 59.9m summit height and a 28.0m bwlch height, with these values giving this hill 31.9m of drop, which is sufficient for it to be classified as a 30-99m Twmpau.
The full details for the hill are:
Group: Moelwynion
Name: Bryn y Gwynt
OS 1:50,000 map: 124
Summit Height: 59.9m (converted to OSGM15, Trimble GeoXH 6000)
Summit Grid Reference: SH 59949 44919 (Trimble GeoXH 6000)
Bwlch Height: 28.0m (LIDAR)
Bwlch Grid Reference: SH 60224 45248 & SH 60226 45258 & SH 60227 45259 (LIDAR)
Drop: 31.9m (Trimble GeoXH 6000 summit and LIDAR bwlch)
My thanks to Aled Williams for sending the details of this hill to me.
Mapping Mountains - Hill Reclassifications - 30-99m Twmpau
Mynydd Carreg (SH 163 291) – 100m Twmpau reclassified to 30-99m Twmpau (16th 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 228 293) and 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 - 30-99m Twmpau
Ynys Fadog (SH 564 398) – Double Sub-Twmpau addition (15th reclassification)
Survey post for Ynys Fadog
There has been an addition to the Twmpau (thirty welsh metre prominences and upward) list with this hill being included in the Double Sub-Twmpau that accompanies the 30-99m height band. Accompanying all the 100m height band of hills within the Twmpau are sub lists with the one attached to this list being entitled the 30-99m Sub-Twmpau. There is a second sub category that accompanies the 30-99m height band and which is entitled the Double Sub-Twmpau.
The criteria for 30-99m Twmpau status is all Welsh hills at or above 30m and below 100m in height with 30m minimum drop, the criteria for 30-99m Sub-Twmpau status is all Welsh hills at or above 30m and below 100m in height with 20m or more and below 30m of drop, whilst the criteria for Double Sub-Twmpau status is all Welsh hills at or above 20m and below 30m in height with 20m or more and below 30m of drop.
The details relating to this hill’s addition are retrospective as it was proposed as a possible new P30 by Aled Williams, and subsequently surveyed with the Trimble GeoXH 6000 on the 1st February 2014.
Prior to the survey with the Trimble this hill was unclassified, with the current Ordnance Survey 1:50,000 Landranger map, 1:25,000 Explorer map and the enlarged mapping hosted on the Geograph website all giving the hill an uppermost 20m ring contour, which implies that the hill does not have sufficient prominence for P30 status but may attain Double Sub-Twmpau status with 20m or more of drop.
The hill is in the Moel Hebog group of hills and is placed in the Region of North Wales (Region A, Sub-Region A1) with its Cardinal Hill being Pt. 734m (SH 525 502) and is situated between the communities of Porthmadog to its south and Tremadog to its north-west, with the A 487 road to its immediate south. The hill can be visited from this road where a lay-by gives access through a gate into woodland that covers this and other adjacent small hills.
The name of the hill is Ynys Fadog and as its name implies it forms an island, which is attached to two higher hills both of which are known as Ynys Hir (SH 566 396 and SH 566 398) which are to the south-east and east respectively, with all three hills now being landlocked, it is included as a Double Sub-Twmpau as the survey with the Trimble GeoXH 6000 produced a summit height of 27.8m (converted to OSGM15) and with an estimated bwlch height of c 3m, it gives this hill c 25m of drop.
The full details for the hill are:
Cardinal Hill: Pt. 734m (SH 525 502)
Summit Height: 27.8m (converted to OSGM15)
Name: Ynys Fadog
OS 1:50,000 map: 124
Summit Grid Reference: SH 56464 39823
Drop: c 25m
 |
| The wooded summit of Ynys Fadog (SH 564 398) |
Myrddyn Phillips (July 2017)
Mapping Mountains - Hill Reclassifications - 30-99m Twmpau
Pt. 36.9m, Ynys Hir (SH 566 398) – 30-99m Sub-Twmpau addition (14th reclassification)
Summit survey post for Pt. 36.9m, Ynys Hir
Bwlch survey post for Pt. 36.9m, Ynys Hir
Significant Height Revisions post for Pt. 36.9m, Ynys Hir
There has been an addition to the Twmpau (thirty welsh metre prominences and upward) list with this hill being included in the 30-99m height band. Accompanying all the 100m height band of hills within the Twmpau are sub lists with the one attached to this list being entitled the 30-99m Sub-Twmpau.
The criteria for 30-99m Twmpau status is all Welsh hills at or above 30m and below 100m in height with 30m minimum drop, whilst the criteria for 30-99m Sub-Twmpau status is all Welsh hills at or above 30m and below 100m in height with 20m or more and below 30m of drop.
The details relating to this hill’s addition are retrospective as it was proposed as a possible new P30 by Aled Williams, and subsequently surveyed with the Trimble GeoXH 6000 on the 1st February 2014.
Prior to the survey with the Trimble this hill was unclassified, with the current Ordnance Survey 1:50,000 Landranger map, 1:25,000 Explorer map and the enlarged mapping hosted on the Geograph website all giving the hill an uppermost 20m ring contour, which implies that the hill does not have sufficient prominence for P30 status but may attain Sub-Twmpau status with 20m or more of drop.
The hill is in the Moel Hebog group of hills and is placed in the Region of North Wales (Region A, Sub-Region A1) with its Cardinal Hill being Pt. 734m (SH 525 502) and is situated between the communities of Porthmadog to its south and Tremadog to its north north-west, with the A 487 road to its immediate south. The hill can be visited from this road where a lay-by gives access through a gate into woodland that covers this and other adjacent small hills.
The name the hill is listed by is Pt. 36.9m, Ynys Hir and as its name implies it forms an island, which is attached to the higher hill known as Ynys Hir (SH 566 396) which is to the immediate south, with both hills now being landlocked, it is included as a 30-99m Sub-Twmpau as the survey with the Trimble GeoXH 6000 produced a summit height of 36.9m (converted to OSGM15) and a bwlch height of 11.1m (converted to OSGM15), with these values giving this hill 25.8m of drop.
The full details for the hill are:
Cardinal Hill: Pt. 734m (SH 525 502)
Summit Height: 36.9m (converted to OSGM15)
Name: Pt. 36.9m, Ynys Hir
OS 1:50,000 map: 124
Summit Grid Reference: SH 56649 39840
Drop: 25.8m (converted to OSGM15)
 |
| The Trimble GeoXH 6000 set-up position at the summit of Pt. 36.9m (SH 566 398). Photo: Aled Williams |
For details on the summit survey and the bwlch survey that confirmed this hill’s 30-99m Sub-Twmpau status
Myrddyn Phillips (July 2017)
Mapping Mountains - Hill Reclassifications - 30-99m Twmpau
Ynys Hir (SH 566 396) – 30-99m Twmpau addition (13th reclassification)
Survey post for Ynys Hir
Significant Height Revisions post for Ynys Hir
There has been an addition to the Twmpau (thirty welsh metre prominences and upward) list with this hill being included in the 30-99m height band. Accompanying all the 100m height band of hills within the Twmpau are sub lists with the one attached to this list being entitled the 30-99m Sub-Twmpau.
The criteria for 30-99m Twmpau status is all Welsh hills at or above 30m and below 100m in height with 30m minimum drop, whilst the criteria for 30-99m Sub-Twmpau status is all Welsh hills at or above 30m and below 100m in height with 20m or more and below 30m of drop.
The details relating to this hill’s addition are retrospective as it was proposed as a possible new P30 by Aled Williams, and subsequently surveyed with the Trimble GeoXH 6000 on the 1st February 2014.
Prior to the survey with the Trimble this hill was unclassified as the Ordnance Survey 1:50,000 Landranger map, 1:25,000 Explorer map and the enlarged mapping hosted on the Geograph website all give the hill an uppermost 20m ring contour, implying that its height is not sufficient for P30 status.
The hill is in the Moel Hebog group of hills and is placed in the Region of North Wales (Region A, Sub-Region A1) with its Cardinal Hill being Pt. 734m (SH 525 502) and is situated between the communities of Porthmadog to its south and Tremadog to its north north-west, with the A 487 road to its immediate south. The hill can be visited from this road where a lay-by gives access through a gate into woodland that covers this and other adjacent small hills.
The name of the hill is Ynys Hir and as its name implies it forms an island, which is now landlocked, it is included as a 30-99m Twmpau as the survey with the Trimble GeoXH 6000 produced a summit height of 37.3m (converted to OSGM15), and with an estimated bwlch height of c 3m it gives this hill c 34m of drop.
The full details for the hill are:
Cardinal Hill: Pt. 734m (SH 525 502)
Summit Height: 37.3m (converted to OSGM15)
Name: Ynys Hir
OS 1:50,000 map: 124
Summit Grid Reference: SH 56695 39693
Drop: c 34m
 |
| Beyond the cliffs and vegetation is the summit of Ynys Hir (SH 566 396) which has been confirmed as a 30-99m Twmpau |
Myrddyn Phillips (July 2017)
Mapping Mountains - Hill Reclassifications - 30-99m Twmpau
Dinas Dinlle (SH 436 564) – 30-99m Twmpau addition (12th reclassification)
Survey post for Dinas Dinlle
There has been an addition to the Twmpau (thirty welsh metre prominences and upward) list with this hill being included in the 30-99m height band. Accompanying all the 100m height band of hills within the Twmpau are sub lists with the one attached to this list being entitled the 30-99m Sub-Twmpau.
The details relating to this hill’s addition are retrospective as its P30 status is due to detail on the Ordnance Survey enlarged mapping hosted on the Geograph website and which was first spotted by Chris Watson, its status has subsequently been confirmed from a survey with the Trimble GeoXH 6000 which was conducted on the 26th December 2013.
The criteria for 30-99m Twmpau status is all Welsh hills at or above 30m and below 100m in height with 30m minimum drop, whilst the criteria for 30-99m Sub-Twmpau status is all Welsh hills at or above 30m and below 100m in height with 20m or more and below 30m of drop.
Prior to Chris Watson raising the probability of this hill being a P30 and its subsequent survey it had remained unclassified, as the Ordnance Survey 1:50,000 Landranger map gives a 31m summit spot height and bwlch contouring between 0m – 10m, whilst the 1:25,000 Explorer map gives an uppermost 30m ring contour and the same bwlch contouring, this implied that the hill did not have the required 30m of drop to qualify for Twmpau status.
The hill is positioned in the Moel Hebog range and is placed in the Region of North Wales (Region A, Sub-Region A1) with its Cardinal Hill being Mynydd Mawr (SH 539 546) and is situated on the outskirts of the small community that takes its name from the hill; Dinas Dinlle, and is positioned with the sea to its immediate west which has eroded some of its western slopes over recent years. If wanting to visit the hill it can be easily accessed from the car park adjacent to the sea front from where a path heads up its northern slopes.
The name of the hill is Dinas Dinlle and as its name implies the upper section of the hill comprises an ancient hill fort, it was included as a 30-99m Twmpau as the Ordnance Survey enlarged mapping hosted on the Geograph website has contours at 5m intervals giving the hill an uppermost contour of 35m and bwlch contouring between 0m – 5m, these values give the hill an estimated drop of c 31m – c 32m. The summit of this hill has subsequently been surveyed with the Trimble GeoXH 6000 as 34.7m (converted to OSGM15) and with a 4.1m bwlch height ascertained from LIDAR analyis, these values give this hill 30.6m of drop.
The full details for the hill are:
Cardinal Hill: Mynydd Mawr
Summit Height: 34.7m (converted to OSGM15)
Name: Dinas Dinlle
OS 1:50,000 map: 115, 123
Summit Grid Reference: SH 43676 56438
Drop: 30.6m
 |
| Dinas Dinlle (SH 436 564) confirmed as a 30-99m Twmpau |
Myrddyn Phillips (July 2017)
Mapping Mountains - Hill Reclassifications - 30-99m Twmpau
Coed Bodlondeb (SH 779 781) – 30-99m Sub-Twmpau reclassified to 30-99m Twmpau (11th reclassification)
Survey post for Coed Bodlondeb
Significant Name Changes post for Coed Bodlondeb
There has been a reclassification to the Twmpau (thirty welsh metre prominences and upward) list with this hill being included in the 30-99m Twmpau height band. Accompanying all the 100m height band of hills within the Twmpau are sub lists with the one attached to this list being entitled the 30-99m Sub-Twmpau. The details relating to this hill’s addition are retrospective as its inclusion as a P30 was reported on Mapping Mountains on the 17th December 2015.
The criteria for 30-99m Twmpau status is all Welsh hills at or above 30m and below 100m in height with 30m minimum drop, whilst the criteria for 30-99m Sub-Twmpau status is all Welsh hills at or above 30m and below 100m in height with 20m or more and below 30m of drop.
Prior to this hill’s inclusion as a 30-99m Twmpau it was listed with an estimated c 27m of drop based on the Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer maps giving the hill an uppermost 50m ring contour and bwlch contouring between 20m – 30m, resulting in an estimated summit height of c 53m and an estimated bwlch height of c 26m.
The hill is positioned in the Carneddau group of hills and is placed in the Region of North Wales (Region A, Sub-Region A1) with its Cardinal Hill being Tal y Fan (SH 729 726) and is situated on the northern outskirts of Conwy with the Afon Conwy to its immediate north and east.
As the name of the hill suggests it is a part of a wood which is made up of deciduous trees and for those wanting to visit permission should be sought as it is not a part of designated open access land. However, access is relatively easy with public parking available next to where the Offices are marked to the south of the summit on Ordnance Survey maps, and there are a number of paths marked on the map that head up to, or contour around the top of the hill.
The name of the hill is Coed Bodlondeb and it is included as a 30-99m Twmpau as the Ordnance Survey enlarged mapping hosted on the Geograph website has contours at 5m intervals giving the hill an uppermost contour of 55m and bwlch contouring between 20m – 25m. Therefore the summit is estimated as being c 57m high and the bwlch estimated as being c 23m high, with these values giving this hill c 34m of drop.
Since this hill was originally included in the Twmpau list the summit has been surveyed with the Trimble GeoXH 6000 and the bwlch of the hill has been analysed via LIDAR and the resulting values are given below.
Since this hill was originally included in the Twmpau list the summit has been surveyed with the Trimble GeoXH 6000 and the bwlch of the hill has been analysed via LIDAR and the resulting values are given below.
The full details for the hill are:
Cardinal Hill: Tal y Fan
Name: Coed Bodlondeb
OS 1:50,000 map: 115
Summit Height: 56.0m (converted to OSGM15)
Summit Grid Reference: SH 77921 78114
Summit Grid Reference: SH 77921 78114
Bwlch Height: 22.9m (LIDAR)
Bwlch Grid Reference: SH 77852 77725 (LIDAR)
Drop: 33.0m (Trimble summit and LIDAR bwlch)
Bwlch Grid Reference: SH 77852 77725 (LIDAR)
Drop: 33.0m (Trimble summit and LIDAR bwlch)
 |
| Gathering data at the summit of Coed Bodlondeb |
For details on the summit survey of Coed Bodlondeb
Myrddyn Phillips (July 2017)
Mapping Mountains - Hill Reclassifications - 30-99m Twmpau
Ynys Gron (SH 596 392) – 30-99m Twmpau reclassified to 30-99m Sub-Twmpau (10th reclassification)
Survey post for Ynys Gron
There has been a reclassification to the Twmpau (thirty welsh metre prominences and upward) list with a 30-99m Twmpau being reclassified to a 30-99m Sub-Twmpau due to surveying 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 21th November 2014.
The criteria for 30-99m Twmpau status is all Welsh hills at or above 30m and below 100m in height with 30m minimum drop, whilst the criteria for 30-99m Sub-Twmpau status is all Welsh hills at or above 30m and below 100m in height with 20m or more and below 30m of drop.
The hill had been listed in the original Welsh P30 lists when published on Geoff Crowder’s v-g.me website with a 96m summit height based on the Ordnance Survey 1:25,000 Outdoor Leisure spot height, with an accompanying note stating ‘98m on 1984 1:50,000 map. Summit being reduced due to quarrying’. When drop values were added to the P30 Master Lists this hill was given an estimated drop of c 50m. The heights quoted appeared on maps of the day, although it was also known that the quarrying activities had already reduced the height of this hill.
The hill is situated in the Moelwynion group of hills and is placed in the Region of North Wales (Region A, Sub-Region A1) with its Cardinal Hill being Moelwyn Mawr (SH 658 448) and is situated between the towns of Porthmadog to the west and Penrhyndeudraeth to the east, and immediately above the busy A 487 road which is to its south.
The hill is not on open access land and the whole of its south-western section forms part of the Garth Quarry, which is operational, and because of this permission to visit should be sought. However, the approach from the east is through woodland and would take a visitor direct to the remaining high point of the hill.
The name of the hill is Ynys Gron, which is a locally known name and it has been reclassified to a 30-99m Sub-Twmpau as the quarry has now obliterated the upper 30m of the hill and reduced it in height to 69.4m, and as its bwlch has been surveyed as 44.3m in height, it gives this hill only 25.1m of drop, which is insufficient for it to remain classified as a P30.
The full details for the hill are:
Cardinal Hill: Moelwyn Mawr
Summit Height: 69.4m (converted to OSGM15)
Name: Ynys Gron
OS 1:50,000 map: 124
Summit Grid Reference: SH 59653 39268
Drop: 25.1m (converted to OSGM15)
|
| The Trimble GeoXH 6000 gathering data at the remaining high point of Ynys Gron |
Myrddyn Phillips (June 2017)
Mapping Mountains - Hill Reclassifications - 30-99m Twmpau
Pt. 23.8m (SM 706 236) - Double Sub-Twmpau addition (9th reclassification)
Survey post for Pt. 23.8m
Please note; since the Trimble GeoXH
6000 summit survey of this hill its connecting bwlch has been analysed via
LIDAR resulting in the hill only having 18.8m of drop, therefore it has
subsequently been deleted from Double Sub-Twmpau status, with the details below
remaining as originally written for historic merit.
The hill did not appear in the Sub-List which accompanied the original Welsh P30 listings on Geoff Crowder’s v-g.me website as the Sub-List only included hills whose map details showed that when surveyed they may stand a chance of qualification to the main P30 list, with the title of the Sub-List being ‘Hills to be surveyed.’ And as this hill only has an uppermost 20m ring contour it was judged that even when surveyed there was no chance of it reaching the dizzying heights of having a minimum of 30m of drop, and therefore it was not included in the Sub-List. However, since first publication this Sub-List has been standardised and now includes all hills that have a minimum of 20m of drop and below 30m of drop.
The Trimble GeoXH 6000 survey that resulted in this hill’s addition as a Double Sub-Twmpau was conducted during the afternoon of 15th May 2016 in beautiful, sunny and still conditions.
As the hill is situated on an island the only way to approach is via boat and the only company with permission to land on Ynys Dewi is Thousand Island Adventures (tel: 01437-721721). The hill can be easily accessed as it rises immediately above where the boat docks, however when I visited it I sought permission to do so as it is off the beaten track as far as visitors are concerned.
The hill does not possess either a map or local name and therefore the point (Pt. 23.8m) notation is being used. It currently has an uppermost 20m ring contour encircling its summit on Ordnance Survey maps and is now joined to the remainder of Ynys Dewi by the walkway leading to the track above where the boat docks. This walkway is elevated above the sea and is man-made, with the natural connection between this small hill and the bulk of the island being a small pebbled bit of land below the track, it is estimated that this natural land is c 2m high.
Therefore the survey with the Trimble GeoXH 6000 resulted in a 23.8m (converted to OSGM15) summit height and with an estimated bwlch height of c 2m, this hill has c 22m of drop and therefore qualifies as a Double Sub-Twmpau.
The full details for the hill are:
Cardinal Island: Ynys Dewi
Summit Height: 23.8m (converted to OSGM15)
Name: Pt. 23.8m
OS 1:50,000 map: 157
Summit Grid Reference: SM 70677 23686
Drop: c 22m
 |
| Pt. 23.8m (SM 706 236) |
Myrddyn Phillips (May 2016)
Mapping Mountains - Hill Reclassifications - 30-99m Twmpau
Foel Fawr (SM 705 225) - 30-99m Sub-Twmpau reclassified to 30-99m Twmpau (8th reclassification)
Survey post for Foel Fawr
There has been a reclassification to the listing of Twmpau (thirty welsh metre prominences and upward) hills due to a recent survey with the Trimble GeoXH 6000. The hill is listed in the 30m–99m height band of Twmpau hills and is situated on the southern part of Ynys Dewi (Ramsey), which is an island to the west of St David’s in south-west Wales.
The hill appeared in the original Welsh P30 listings on Geoff Crowder’s v-g.me website and was included in the Sub-List adjoined to the 30m-99m height band of hills, and was the only hill listed in this Sub-List under the grouping of the Pembrokeshire Islands.
The Trimble GeoXH 6000 survey that resulted in this hill’s reclassification was conducted on the 15th May 2016 in the mid-afternoon in beautiful, sunny and still conditions.
As the hill is situated on an island the only way to approach is via boat and the only company with permission to land on Ynys Dewi is Thousand Island Adventures (tel: 01437-721721). The hill can be easily accessed from where the boat docks as a gravelled track leads up to The Farmhouse from where a good path heads toward the southern part of the island.
The name of the hill is Foel Fawr and it is given a 72m summit spot height on current Ordnance Survey maps, and has been listed with an estimated bwlch height of c 43m based on bwlch contouring between 40m – 45m, these values gave the hill c 29m of drop and therefore it remained listed as a Sub-Twmpau.
Two points were surveyed for summit position and also for bwlch position, these are given below:
Summit 1: 72.0m (71.954m, converted to OSGM15)) at SM 70542 22567
Summit 2: 71.8m (71.821m, converted to OSGM15) at SM 70539 22566
Bwlch 1: 41.8m (41.764m, converted to OSGM15)) at SM 70504 22667
Bwlch 2: 41.9m (41.899m, converted to OSGM15) at SM 70511 22665
The surveys for bwlch position were conducted on the valley to valley traverse and therefore the higher result is taken when calculating the drop value for the hill.
Therefore the survey with the Trimble GeoXH 6000 resulted in a 72.0m (converted to OSGM15) summit height and a 41.9m (converted to OSGM15) bwlch height, with these values giving the hill 30.1m of drop. As the minimum drop for qualification to the main Twmpau list is 30m this means that Foel Fawr is reclassified from a Sub-Twmpau to a Twmpau.
The full details for the hill are:
Cardinal Island: Ynys Dewi
Summit Height: 72.0m (converted to OSGM15)
Name: Foel Fawr
OS 1:50,000 map: 157
Summit Grid Reference: SM 70542 22567
Drop: 30.1m (converted to OSGM15)
 |
| Foel Fawr (SM 705 225) now reclassified from a Sub-Twmpau to a Twmpau |
Myrddyn Phillips (May 2016)
Mapping Mountains - Hill Reclassifications - 30-99m Twmpau
Ynys Fach (SM 822 327) - 30-99m Twmpau reclassified to 30-99m Sub-Twmpau (7th reclassification)
Survey post for Ynys Fach
There has been a reclassification to the listing of the Twmpau (thirty welsh metre prominences and upward) hills due to a recent survey with the Trimble GeoXH 6000. The hill is listed in the 30m – 99m height band of Twmpau hills and is situated on the northern Pembrokeshire coast close to the small communities of Porthgain to its west and Trefin (Trevine) to its east.
The hill is better described as an island, and even more so as a tidal island, and is connected to the mainland of Wales by a pebbled beach that according to maps is cut off from the mainland at high water. It can be approached by boat, but an ascent of the island is feasible, albeit steep and potentially dangerous, from the mainland. This approach starts from directly opposite the island and necessitates finding a route down bi-passing the rock and cliffs that predominate this part of the coastline. If attempting this route please be careful.
The island was surveyed on 14th May 2016 on a beautiful sunny evening in the company of Adrian Rayner, Ayako and Rob Woodall. It was Rob’s suggestion to go and have a look at it, and he found the route down to the pebbled beach which constitutes this island’s connecting bwlch.
The name of the island is Ynys Fach and it first appeared in a hill list on Geoff Crowder’s v-g.me website as a part of the original listing of Welsh P30s taking in the 100m height bands below the height of 500m.
Ynys Fach is given an uppermost contour ring of 30m on current Ordnance Survey maps with no adjoined spot height. However, the Ordnance Survey Six Inch map revised in 1906 and published in 1908 gives a 99ft height for the island, this is when the composition of the name was presented as Ynys Fâch, as opposed to the current Ynys-fach. The 99ft spot height was later given on the Ordnance Survey 1:25,000 Historical map, with 99ft being an approximate 30.2m in metric measurement.
Two points were surveyed for summit position and these are given below:
Summit 1: 30.8m (30.789m, converted to OSGM15) at SM 82209 32743
Summit 2: 30.7m (30.727m, converted to OSGM15) at SM 82217 32752
The data set for the bwlch was remarkably good when considering that the equipment was placed in what resembled an enclosed and walled canyon, with the result being 1.2m (1.225m, converted to OSGM15) at SM 82180 32693. These values give Ynys Fach a drop of only 29.6m and therefore it is reclassified from a 30-99m Twmpau to a Sub-Twmpau.
The full details for the hill are:
Cardinal Hill: Garn Fawr
Summit Height: 30.8m (converted to OSGM15)
Name: Ynys Fach
OS 1:50,000 map: 157
Summit Grid Reference: SM 822 327
Drop: 29.6m (converted to OSGM15)
 |
| Ynys Fach (SM 822 327) now reclassified from a Twmpau to a Sub-Twmpau |
Mapping Mountains - Hill Reclassifications - 30-99m Twmpau
Daufraich (SM 661 236) - Double Sub-Twmpau addition (6th reclassification)
Survey post for Daufraich
There has been an addition to the Sub category within the 30–99m Twmpau (thirty welsh metre prominences and upward) hill list instigated by a survey with the Trimble GeoXH 6000. The hill is better described as an island and is situated to the west of St David’s in south-west Wales, and forms part of the chain of islands known as the Bishops and Clerks.
The Trimble GeoXH 6000 survey that resulted in this hill’s inclusion as a 30–99m Sub-Twmpau was conducted on the 14th May 2016 in the early afternoon on a fine day in good, dry and sunny conditions. The trip to this and other islands was organised by Adrian Rayner and the survey took place in the company of Adrian, Rob Woodall, Bob Kerr and Jon Glew, with Sheila Glew, Akako and Sarah Kerr remaining on the RIB whilst we were on the island.
Not surprisingly the island can only be accessed by boat, and although landing is relatively easy the way to the summit involves a scramble, and although not difficult it is exposed, with the prospect of an undignified dunking in the sea a distinct probability if one foot hold proves a wee bit slippy.
The name of the island is Daufraich and it comprises two parts, with its easterly high point being given the map height of 20m, and its westerly high point being given two positions of 21m high on current Ordnance Survey maps. We only had time to land on the westerly part of the island which proved visually higher than the easterly part. I also only had time for one survey, and consensus of opinion was that the highest part of the island was where the south-eastern 21m spot height appears on the ground, with the ground where the north-western 21m spot height is positioned being assessed as slightly lower.
Daufraich was not included in the Sub-List which accompanied the original listing of 30m -99m hills that appeared on Geoff Crowders v-g.me website, as that Sub-List comprised ‘Hills to Survey’ and as this island was under 30m in height it was not included as the only hills that were, were those deemed to have chance of qualifying for the main P30 list after having been surveyed. However, this Sub-List has now been standardised and includes all hills that are known to have at least 20m of drop and below 30m of drop.
The survey with the Trimble GeoXH 6000 resulted in a 21.7m (converted to OSGM15) summit height, which as an island is also this hill’s drop value, and therefore confirming its entry in to the 30–99m Sub-Twmpau ranks.
The full details for the hill are:
Cardinal Island: Bishops and Clerks
Summit Height: 21.7m (converted to OSGM15)
Name: Daufraich
OS 1:50,000 map: 157
Summit Grid Reference: SM 66199 23673
Drop: 21.7m (converted to OSGM15)
 |
| Daufraich (SM 661 236) the new Double Sub-Twmpau |
Myrddyn Phillips (May 2016)
Mapping Mountains - Hill Reclassifications - 30-99m Twmpau
Moel y Gadair (SH 521 391) 30-99m Twmpau reclassified to 30-99m Sub-Twmpau (5th reclassification)
Summit survey post for Moel y Gadair
Bwlch survey post for Moel y Gadair
This hill has subsequently been reinstated to 30-99m Twmpau status due to LIDAR analysis indicating this hill is a natural P30, with the raised road passing over the bwlch considered a relatively recent man-made construct; therefore it is excluded from the height of the bwlch.
There has been a reclassification to the listing of 30-99m Twmpau (thirty welsh metre prominences and upward) due to a survey with the Trimble GeoXH 6000 and subsequent LIDAR analysis. The hill is listed in the 30–99m height band of Twmpau hills and is situated to the south-west of the small community of Pentrefelin, which is situated between Porthmadog to the east and Cricieth to the south-west.
The hill has been reclassified from a 30-99m Twmpau to a 30-99m Sub-Twmpau, and re-joins these ranks after being originally listed in the Hills to be surveyed Sub-List that appeared on Geoff Crowder’s v-g.me website. On reassessment the hill was promoted to full P30 status due to bwlch contour interpolation, with a drop value of c 30m based on a summit spot height of 67m and an estimated bwlch height of c 37m.
The hill is named Moel y Gadair and its summit was surveyed with the Trimble GeoXH 6000 on the 15th June 2015 giving a height of 66.7m. During the 15th June 2015 survey the contours at the bwlch were misinterpreted resulting in the second bwlch survey which was conducted on the 23rd February 2016 and the subsequent LIDAR analysis resulting in a bwlch height of 36.8m.
Therefore, the reclassification of this hill to 30-99m Sub-Twmpau status is due to a 66.7m summit height and a 36.8m bwlch height, with these values giving this hill 29.9m of drop which is insufficient for 30-99m Twmpau status.
Therefore, the reclassification of this hill to 30-99m Sub-Twmpau status is due to a 66.7m summit height and a 36.8m bwlch height, with these values giving this hill 29.9m of drop which is insufficient for 30-99m Twmpau status.
The full details for the hill are:
Group: Moel Hebog
Summit Height: 66.7m (converted to OSGM15)
Name: Moel y Gadair
OS 1:50,000 map: 124
Summit Grid Reference: SH 52165 39135
Drop: 29.9m (Trimble summit and LIDAR bwlch)
 |
| Moel y Gadair (SH 521 391) is now reclassified from a 30-99m Twmpau to a 30-99m Sub-Twmpau |
For details on the summit survey and the bwlch survey that resulted in this hill being reclassified to a 30-99m Sub-Twmpau status.
My thanks to Aled Williams for his initial LIDAR analysis
Myrddyn Phillips (February 2016)
My thanks to Aled Williams for his initial LIDAR analysis
Myrddyn Phillips (February 2016)
Mapping Mountains - Hill Reclassifications - 30-99m Twmpau
Castell Cricieth (SH 500 377) - 30-99m Twmpau addition (4th reclassification)
Survey post for Castell Cricieth
There has been an addition to the listing of Twmpau (thirty welsh metre prominences and upward) hills due in part to a recent survey with the Trimble GeoXH 6000. The hill is listed in the 30m-99m height band of Twmpau hills and is situated in the town of Cricieth.
Its P30 status was first discovered by Alex Cameron who rightly judged that with a 48m summit spot height which appears on the Ordnance Survey enlarged mapping hosted on the Geograph website, and with bwlch contouring between c 15m – c 20m, with an estimated bwlch height of c 18m, this hill should be listed as a P30 with c 30m of drop.
The hill is Castell Cricieth which as its name implies has a castle on top of it.
This hill is one of the rarities that have not appeared in previous Sub-Lists before its entrance as a fully-fledged P30.
The full details for the hill are:
Cardinal Hill: Moel Hebog
Summit Height: 49.6m (converted to OSGM15)
Name: Castell Cricieth
OS 1:50,000 map: 123
Summit Grid Reference: SH 500 377
Drop: 30.3m (converted to OSGM15)
 |
| Castell Cricieth (SH 500 377) P30 status now confirmed by the Trimble GeoXH 6000 |
For details on the survey that confirmed this hill's status as a 30-99m Twmpau please click {here}
Myrddyn Phillips (June 2015)
Mapping Mountains - Hill Reclassifications - 30-99m Twmpau
Carreg yr Eryr (SH 526 378) - 30-99m Sub-Twmpau reclassified to 30-99m Twmpau (3rd reclassification)
Survey post for Carreg yr Eryr
There has been a new addition to the listing of Twmpau (thirty welsh metre prominences and upward) hills due to a recent survey with the Trimble GeoXH 6000. The hill is listed in the 30m-99m height band of Twmpau hills and is situated on the outskirts of Morfa Bychan overlooking Black Rock Sands to its east and Castell Cricieth to its west.
The first time Carreg yr Eryr ever appeared in a hill list was in 2003 when the original Welsh P30 hills under 500m in height were published on Geoff Crowder’s v-g.me website. It was then listed in the Sub-List which was named ‘Hills to Survey’. The reason for this was that Carreg yr Eryr was not given a summit and bwlch spot height that gave it a minimum of 30m of drop on the then current Ordnance Survey map, because of this it was listed as a Sub. When this list was first published on Geoff’s website it did not include a drop value for each hill, although the qualification for the main list and the Sub-List was based on drop. These drop values were added at a later date.
When these drop values were added to the list I also decided to include hills in the Main P30 Twmpau list through interpolation of map contours, although some of these details were passed onto Geoff, the great majority were not. When drop figures were added to the list I gave Carreg yr Eryr c 30m of drop and promoted it into the ranks of P30 hills. This drop value was estimated from its 53m summit spot height and an estimated bwlch height of c 23m based on the 1:25,000 map bwlch contouring between c 20m – c 30m. Since this hill was promoted into the P30 ranks the Ordnance Survey enlarged map on the Geograph website has been made available, and this map has contour intervals of 5m and gives the bwlch contouring between c 20m and c 25m, with an estimated bwlch height of c 23m, so the hill remained listed as a P30. Even though the hill had been promoted in my list the details were never made public, so it was now time to have it Trimbled and to confirm its status via the Mapping Mountains blog.
The full details for the hill are:
Cardinal Hill: Moel Hebog
Summit Height: 53.3m (converted to OSGM15)
Name: Carreg yr Eryr
OS 1:50,000 map: 124
Summit Grid Reference: SH 526 378
Drop: 30.9m (converted to OSGM15)
 |
| Carreg yr Eryr (SH 526 378) P30 status now confirmed by the Trimble GeoXH 6000 |
For details on the survey that confirmed this hill's 30m-99m Twmpau status please click {here}
Myrddyn Phillips (June 2015)
Mapping Mountains - Hill Reclassifications - 30-99m Twmpau
Ynys Tywyn (SH 571 385) - Double Sub-Twmpau addition (2nd reclassification)
Survey post for Ynys Tywyn
There has been an addition to the 30-99m Twmpau list with this hill entering the category of Double Sub-Twmpau. The name of the hill is Ynys Tywyn (SH 571 385) and it is situated at the end of the Cob in Porthmadog in north-west Wales.
Ynys Tywyn has a small uppermost 20m contour ring on Ordnance Survey maps, but no spot height, and a recent survey with the Trimble GeoXH 6000 confirms that the hill is over 20m but under 30m in height and as it is the high point of an island that is now connected to Porthmadog by the Cob, and therefore its height is also considered to be its drop, it has been included in the Double Sub-Twmpau category. The summit is crowned by a large flat rock and gorse bushes and has fine views over the Afon Glaslyn to the higher mountains of Eryri.
Ynys Tywyn has a small uppermost 20m contour ring on Ordnance Survey maps, but no spot height, and a recent survey with the Trimble GeoXH 6000 confirms that the hill is over 20m but under 30m in height and as it is the high point of an island that is now connected to Porthmadog by the Cob, and therefore its height is also considered to be its drop, it has been included in the Double Sub-Twmpau category. The summit is crowned by a large flat rock and gorse bushes and has fine views over the Afon Glaslyn to the higher mountains of Eryri.
The full details for the hill are:
Cardinal Hill: Moel Hebog
Summit Height: 21.8m (converted to OSGM15)
Name: Ynys Tywyn
OS 1:50,000 map: 124
Summit Grid Reference: SH 571 385
Drop: 21.8m (converted to OSGM15)
.jpg) |
| Ynys Tywyn (SH 571 385) is now confirmed as a Double SubTwmpau |
For details on the survey that promoted this hill to Double Sub-Twmpau status please click {here}
Mapping Mountains - Hill Reclassifications - 30-99m Twmpau
Ynys Glog (SH 596 398) and Ynys Berfedd (SH 599 398) - 30-99m Twmpau additions (1st reclassification)
Survey post for Ynys Glog
Survey post for Ynys Berfedd
There have been three new Welsh island P30 hills recently discovered. These additions to the 30-99m Twmpau list were found by Aled Williams through map study and local knowledge of the area, with two of these hills accepted automatically to the listing of Twmpau hills and with the other hill entering the Twmpau list through surveying with the Trimble GeoXH 6000.
The two hills automatically accepted in to the 30-99m Twmpau list are Ynys Glog (SH 596 398) and Ynys Berfedd (SH 599 398). Whilst the other hill is named Ynys Hir (SH 566 396) which was confirmed as a P30 through surveying with the Trimble GeoXH 6000.
Aled considered the hill at SH 566 396 and its adjacent hill at SH 566 398 which is also known as Ynys Hir as suitable candidates for surveying with a high chance of promotion to the P30 ranks, and considered that the uppermost 20m ring contour given to both hills on the Ordnance Survey enlarged mapping hosted on the Geograph website was incorrect and a misrepresentation of their actual height.
A note from Aled:
Two New P30 Hills
Name: Ynys Glog
Height: 40.6m (converted to OSGM15)
Drop: 32.7m (converted to OSGM15)
Grid Reference: SH 59647 39826
Name: Ynys Berfedd
Height: 42.9m (converted to OSGM15)
Drop: 36.1m (converted to OSGM15)
Grid Reference: SH 59943 39865
Aled Williams (03/02/2014).
Analysis of OS enlarged mapping on the Geograph website confirms two P30 hills that are absent from both the '30-99m Twmpau' list by Myrddyn Phillips (2004) and the 'Tumps' list by Mark Jackson (2009). I bring this information to the attention of the authors.
Name: Ynys Glog
Height: 40.6m (converted to OSGM15)
Drop: 32.7m (converted to OSGM15)
Grid Reference: SH 59647 39826
Name: Ynys Berfedd
Height: 42.9m (converted to OSGM15)
Drop: 36.1m (converted to OSGM15)
Grid Reference: SH 59943 39865
Aled Williams (03/02/2014).
The discovery of new P30’s is not a rarity, but what is unusual is that each of these hills was once an island that is now landlocked in the area known as Traeth Mawr, this is near to Aled’s home in Porthmadog. Subsequently all of these hills have been surveyed using the Trimble GeoXH 6000 and their respective results are given above.
For more detail of the Trimble survey that promoted Ynys Hir to 30-99m Twmpau status click {here}
A post by Aled on the land known as Traeth Mawr and its many small islands is due for publication in the Guest Contributor page on the Mapping Mountains blog in March.
.jpg) |
| Aled Williams at the summit of Ynys Hir (SH 566 396) |
Subscribe to:
Posts (Atom)