Mapping Mountains – Hill Reclassifications – 800m Twmpau / 700m Twmpau

Pen y Gadair Fawr (SO 229 287) – 800m Twmpau reclassified to 700m Twmpau

There has been a reclassification to the listing of Twmpau (thirty welsh metre prominences and upward) hills due to analysis of LIDAR data by Aled Williams.  The hill was listed in the 800m height band of P30 Twmpau hills and it has now been reclassified to a 700m Twmpau.

The criteria for 700m Twmpau status is all Welsh hills at or above 700m and below 800m in height with 30m minimum drop, whilst the criteria for 800m Twmpau status is all Welsh hills at or above 800m and below 900m in height with 30m minimum drop.  Details to the 700m Twmpau were published on Mapping Mountains on 15^th April 2015, and details to the 800m Twmpau were published on Mapping Mountains on the 15^th March 2015.

The name of the hill is Pen y Gadair Fawr and it had been listed in the 800m height band of Twmpau hills, based on the 800m summit spot height that appears on Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer maps.  With the 800m height on Ordnance Survey maps originating from the 2624ft (799.8m) imperial bench mark height on the series of old Six-Inch maps.

The hill is situated on one of the central ridges that forms the Mynyddoedd Duon (Black Mountains) group of hills with its Cardinal Hill being Waun Fach (SO 215 299) and is placed in the Region of South Wales (Region C, Sub-Region C3).  It is situated between the steam valleys of the Grwyne Fawr to its north-east and the Grwyne Fechan to its south, with the town of Talgarth towards the north-west and Y Gelli Gandryll (Hay-on-Wye) towards the north.

As the hill is a part of designated open access land it can be accessed from most directions, however an extended circular walk taking in the ridge upon which it is positioned in conjunction with the ridge to its west is a good way to accustom oneself with this hill range.

The reclassification of Pen y Gadair Fawr to 700m Twmpau status is due to the analysis of LIDAR data by Aled Williams.  LIDAR (Light Detection & Ranging) is highly accurate height data that is now freely available for much of England and Wales.

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

Pen y Gadair Fawr

Summit Height:  799.8m

Summit Grid Reference:  SO 22944 28758

Bwlch Height:  753.2m

Bwlch Grid Reference:  SO 22657 29359

Drop:  46.6m

Therefore, the 799.8m LIDAR data produced for the summit position at SO 22944 28758 and the 753.2m LIDAR data produced for the bwlch position at SO 22657 29359 gives this hill 46.6m of drop, and as the summit height is below 800m it is reclassified to a 700m Twmpau with a 799.8m summit height.

This now revises the total in the 800m and 700m Twmpau which will be updated accordingly.

The full details for the hill are:

Cardinal Hill:  Waun Fach

Summit Height:  799.8m (LIDAR data)

Name:  Pen y Gadair Fawr

OS 1:50,000 map:  161

Summit Grid Reference:  SO 22944 28758  

 

Drop:  46.6m (LIDAR data)

Pen y Gadair Fawr (SO 229 287) now reclassified from an 800m Twmpau to a 700m Twmpau

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

Myrddyn Phillips (October 2017)

Mapping Mountains – Hill Reclassifications – 100m Twmpau / 30-99m Twmpau

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

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 28^th 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

For details on the survey that reclassified this hill from a 100m Twmpau to a 30-99m Twmpau

Myrddyn Phillips (September 2017)

Mapping Mountains – Hill Reclassifications – 200m Twmpau

Y Pincin (SH 723 581) – 200m Twmpau addition

There has been a confirmation of an addition to the 200m Twmpau (thirty welsh metre prominences and upward) ranks of hills due to a survey with the Trimble GeoXH 6000, with these details being retrospective as the survey that confirmed this addition was conducted on the 24^th December 2013.

The criteria for 200m Twmpau status is all Welsh hills at or above 200m and below 300m in height with 30m minimum drop, with an accompanying sub list entitled the 200m Sub-Twmpau with the criteria for this sub category being all Welsh hills at or above 200m and below 300m in height with 20m or more and below 30m of drop. 

This hill did not appear in the original Welsh P30 lists when published on Geoff Crowder’s v-g.me website even though the hill is given a 264m summit spot height on the Ordnance Survey 1:25,000 Explorer map and has bwlch contouring between 220m – 230m.  Its addition to the P30 ranks was announced shortly before the hill was surveyed with the Trimble GeoXH 6000, and prior to this survey the hill was listed with c 36m of drop.

The name of the hill is Y Pincin and it is situated in the Carneddau range with its Cardinal Hill being Creigiau Gleision (SH 729 615) and is positioned immediately above the A5 road which is to its south and the small community of Capel Curig.

The upper section of the hill is a part of designated open access land, with a public footpath leaving Capel Curig to the west of the hill and heading toward the summit.  Although this hill makes an enjoyable walk and scramble in its own right, a more fulfilling experience can be had when combining it with its higher neighbours toward the north.

The full details for the hill are:

Cardinal Hill:  Creigiau Gleision

Summit Height:  263.5m (converted to OSGM15)

Name:  Y Pincin

OS 1:50,000 map:  115

Summit Grid Reference:  SH 72357 58126

Drop:  34.7m (converted to OSGM15)

Y Pincin (SH 723 581) has now been confirmed as a 200m Twmpau by a survey with the Trimble GeoXH 6000

For details on the survey that confirmed this hill’s addition as a 200m Twmpau

Myrddyn Phillips (August 2017)

Mapping Mountains – Hill Reclassifications – 200m Twmpau

Dinas Mawr (SH 808 539) – 200m Sub-Twmpau reclassified to 200m Twmpau

There has been a confirmation of a reclassification to the 200m Twmpau (thirty welsh metre prominences and upward) ranks of hills due to a survey with the Trimble GeoXH 6000, with these details being retrospective as the survey that confirmed this reclassification was conducted on the 24^th December 2013.

The criteria for 200m Twmpau status is all Welsh hills at or above 200m and below 300m in height with 30m minimum drop, with an accompanying sub list entitled the 200m Sub-Twmpau with the criteria for this sub category being all Welsh hills at or above 200m and below 300m in height with 20m or more and below 30m of drop. 

This hill was listed in the Hills to be surveyed sub list accompanying the original Welsh P30 lists on Geoff Crowder’s v-g.me website and was only reclassified to P30 status when the sub list was standardised and interpolated drop values were accepted for qualification to the main P30 list.

Prior to the survey with the Trimble GeoXH 6000 the hill was listed with 33m of drop based on the 254m summit spot height that appears on the Ordnance Survey 1:25,000 Explorer map and the 221m bwlch spot height that appears on the Ordnance Survey enlarged mapping hosted on the Geograph website.

The name of the hill is Dinas Mawr and it  is situated in the Mynydd Hiraethog range with its Cardinal Hill being Mwdwl Eithin (SH 917 540) and is positioned immediately above the A5 road which is to its south, and is placed between the small communities of Capel Garmon to the north north-east and Penmachno to the south south-west.

The upper section of the hill is a part of designated open access land and this can be accessed from public footpaths originating from the A5 road south-west of the summit or from a minor lane to the east of the summit.

The full details for the hill are:

Cardinal Hill:  Mwdwl Eithin

Summit Height:  254.0m (converted to OSGM15)

Name:  Dinas Mawr

OS 1:50,000 map:  116

Summit Grid Reference:  SH 80884 53931

Drop:  33.9m (converted to OSGM15)

Dinas Mawr (SH 808 539) this hill's reclassification to 200m Twmpau status is now confirmed by a survey with the Trimble GeoXH 6000

For details on the survey that confirmed the reclassification of this hill to 200m Twmpau status

Myrddyn Phillips (August 2017)