Monday 18 August 2014

Hill Lists – Cymru / Wales – 200m Twmpau updates – Fforest Glud



The first list to the Welsh 200m P30 hills was published on Geoff Crowder’s website v-g.me in 2000; this list preceded the list of TuMPs by nine years, the list proved a very useful resource for the TuMP compilation for this category of hill.

The Welsh 200m P30 list documents all hills in Wales that are at or above 200m in height and are below 300m in height, to qualify for the main list each hill requires a minimum of 30m of prominence.


The hills listed below are updates to the Welsh 200m P30 list originally published on Geoff Crowder's website.  To see the original list click {here}


The original published list had a Sub-List which was entitled ‘Hills to Survey’.  This list consisted of all hills in Wales in the stipulated height band that have a minimum of 20m of prominence, but do not meet the minimum 30m of prominence to enter the main list, according to Ordnance Survey map spot heights and contours.  Nowadays the standard Sub-List takes in all hills that have a minimum of 20m of prominence.  However, the Hills to Survey Sub-List discounted hills whose map spot heights gave a drop value of less than 30m, but more than 20m.  By doing so, the only hills that were Sub-Listed were those that map values dictated stood a chance of entering the main list, for example; if a hill had a summit spot height of 250m and a bwlch spot height of 221m, it was not listed in the Hills to Survey Sub-List as with 29m of drop I thought it did not stand a chance of main list qualification.
 
When compiling the Sub-List I was measuring many hills for P30 status using a basic levelling technique, please click {here} for more information concerning this.  I now know that Ordnance Survey spot heights have a standard margin of uncertainty of + / - 3m associated with their accuracy.  Therefore many hills that were not listed in the original Sub-List may have sufficient drop to enter the main list.  Because of this the Sub-List has been altered to include all hills that have a minimum of 20m of drop but are not known to attain the minimum 30m of drop to enter the main list.

The hills listed below are those major amendments to the original Welsh 200m P30 list as it appears on Geoff’s website.  There are many hills that have been promoted from the Hills to Survey Sub-List to the main list, whilst there are many additions to the Sub-List now that it has been standardised to include all 20m minimum but below 30m drop hills.

When the 200m P30 list was first published it was the first to this category of hills and in some way it and its other 100m height band lists paved the way for Clem’s data that later appeared on the RHB file database and then for the TuMPs listing by Mark Jackson.

As well as the first P30 list to this height band the list is now the first to include a comprehensive Sub-List.

TuMP baggers beware; as the main list also includes P30’s not listed by Mark Jackson, so if you want to visit all P30’s you’ll have to include some non TuMPs to do so.

The list will be updated on a weekly basis and will be done so through each Group category, starting from the north and working south.  The nineteenth Group is Fforest Glud.


Fforest Glud 

North and then east of the Afon Gwy (River Wye) at SO 229 428 to SO 012 563, continuing east, west and then south of the Afon Ieithon (River Ithon) to SO 114 653, continuing south of the River Aran and the Cwm Minwood to bwlch at SO 178 717 and the River Lugg to the border with England at SO 310 650.  Bordering with Beacon Hill to the north, Pegwn Mawr, Gwastedyn Hill and the Elenydd to the west, Mynydd Epynt and Y Mynyddoedd Duon to the south and the border with England to the east. 


Twmpau - 200m updates

Yatt Wood    c 277m    SO 246 584

This hill was listed in the original Welsh 200m P30 list as the Ordnance Survey 1:25,000 Explorer map had an uppermost c 275m ring contour at its summit, and with bwlch contouring between c 240m – c 245m and a bwlch height estimated as c 243m, it gave this hill c 34m of drop.  However, the Dolyhir quarry which started on the south-western slopes of this hill has now expanded and according to latest mapping the natural wooded summit has been quarried away, leaving a high point at around c 255m.  As this hill no longer has a minimum drop of 30m it is deleted from the list.



Sub-Twmpau - 200m updates

Timber Hill Wood    291m    SO 288 638

This hill is a new entry to the Welsh 200m Sub-P30 list as it has a summit spot height of 291m and an estimated bwlch height of c 268m, based on bwlch contouring between c 265m – c 270m.  These values give this hill c 23m of drop.



Pt. 216m    216m    SO 262 609

This hill takes on the Pt. notation as the blog author doesn’t know an appropriate name for it.  In part this is a shame as if still naming hills after near houses or farms there is a building named Knobley to the north-east of this hill’s summit and Knobley Hill sounds a cracking name for a hill!  The bwlch contouring is between c 190m – c 195m with an estimated height of c 193m, giving this hill c 23m of drop.



Pt. 244m    244m    SO 203 434

Positioned just south-westward of Cleirwy (Clyro) this hill has a 244m summit spot height and an estimated bwlch height of c 222m, based on bwlch contouring between c 220m – c 225m, giving the hill c 22m of drop.



Pt. 215m    215m    SO 024 558

A hill that is positioned between two woods; Coed yr Ynys and the Neuadd Plantation, it also has a sawmill situated near to its summit.  As the bwlch height is estimated as c 193m based on bwlch contouring between c 190m – c 200m, it gives this hill c 22m of drop.



Pt. 218m    218m    SO 035 571

Another hill that adopts the Pt. notation for its name as no appropriate name is known for it by the blog author.  With a 218m summit spot height and an estimated bwlch height of c 197m, based on bwlch contouring between c 190m – c 200m, this hill has c 21m of drop.



Pt. 204m    204m    SO 026 546

The summit of this hill is positioned just to the east of the A470 and is another that follows the Pt. notation for its name.  The bwlch contouring is between c 180m – c 190m, with an estimated bwlch height of c 183m, giving this hill a drop of c 21m.



Pt. 292m    292m    SO 288 627

This hill’s qualification as a Welsh 200m Sub-P30 is reliant upon the details on the Ordnance Survey enlarged map on the Geograph website, as this map has a 292m summit spot height and a 272m spot height on the area of the bwlch, giving this hill 20m of drop.



Pt. 248m    248m    SO 060 601

Positioned near to The Lake and Llandrindod Hall this hill has a 248m summit spot height and a 228m spot height at SO 061 607 on the area of the bwlch, with the latter just appearing on the Ordnance Survey enlarged Geograph map.  These values give this hill 20m of drop.



Pt. c 267m    c 267m    SO 117 650

A contentious entry in to the Welsh 200m Sub-P30 list as both summit and bwlch height have been estimated.  The summit as c 267m with its uppermost contour being c 260m, and the bwlch as c 247m, based on bwlch contouring between c 240m – c 250m.  These values give this hill c 20m of drop.



Pt. 247m    247m    SO 062 579

The Ordnance Survey map indicates that the name of Bryn-y-groes that appears next to this hill’s summit is applicable to the farm to the west and not directly to the hill, therefore the Pt. notation is being used for the name of the hill.  The Ordnance Survey enlarged Geograph map has a 247m summit spot height at SO 062 579, and the height of the bwlch has been estimated as c 227m, based on bwlch contouring between c 220m – c 230m, giving this hill c 20m of drop.



Next update due on the 25th August 2014


No comments: