Monday 9 June 2014

Hill Lists – Cymru / Wales – 200m Twmpau updates – Y Berwyn



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 ninth Group is Y Berwyn.



Y Berwyn 
North from the Afon Efyrnwy (River Vyrnwy) and the border with England at SJ 268 205 to SJ 143 114, continuing north of the Afon Banwy to Bwlch y Fedwen at SH 934 138, continuing north of the Afon Dugoed and Afon Cleifion to SH 857 125, continuing east of the Afon Dyfi (River Dovey) to SH 889 219 and then to Bwlch Sirddyn at SH 884 229 and the Afon Groes to SH 894 269, continuing east of the Afon Twrch to SH 881 312 and the Afon Dyfrdwy (River Dee) to Llyn Tegid (Bala Lake) at SH 890 315, continuing south following the Afon Dyfrdwy (River Dee) from SH 929 351 to SH 317 395 and the border with England.  Bordering with Carnedd Wen and Mynydd y Cemaes to the south, Bryniau Dyfi, Aran and Arennig to the west, Bryniau Clwyd to the north and the English border to the east.  



Twmpau - 200m updates

Y Foel    258m    SH 993 117

A promotion from the sub-list as the summit spot height on Ordnance Survey maps is 258m and the height of the bwlch is estimated as c 227m (bwlch contouring between c 220m – c 230m), giving a drop of c 31m.  The hill was originally listed as Foel, the definite article ‘Y’ has now been added.



Sub-Twmpau - 200m updates

Bachrug    c 292m    SJ 138 150

This hill has an estimated summit height of c 292m, with an uppermost summit contour of c 290m.  It has a spot height of 263m on the area of its bwlch on the Ordnance Survey enlarged Geograph map, giving a drop of c 29m.  An ideal hill to survey with the Trimble for P30 status.


Pt. 209m    209m    SJ 163 254

Another hill that uses the Pt. notation as no suitable name has been found for it by the blog author.  The summit has a 209m spot height and with bwlch contouring between c 180m – c 190m, with an estimated bwlch height of c 27m.  It means this hill qualifies for the Sub-list with an estimated drop of c 27m.


Coed Lletty-yr-eos    248m    SJ 132 207

As the uppermost and opposing bwlch contours are relatively close on the valley to valley traverse, the height of the bwlch has been estimated as c 223m (bwlch contouring between c 220m – c 230m).  And with a summit spot height of 248m, this gives the hill c 25m of drop.


Pt. 238m    238m    SJ 129 193

The summit and bwlch of this hill both possess a spot height, 238m and 216m respectively.  This gives the hill a drop of 22m.  The Pt. notation is used as no name is known for the hill by the blog author.


Pt. 213m    213m    SJ 214 218

As the blog author does not know an appropriate name for this hill the Pt. notation is being used.  The summit has a 213m spot height and the bwlch has a 191m spot height on the Ordnance Survey enlarged Geograph map.  Although the latter spot height is not centred, its position is acceptable, giving the hill 22m of drop.


Berwyn    236m    SJ 207 224

The 236m summit height is taken from the Ordnance Survey 1:25,000 map, and with bwlch contouring between c 210m – c 215, with an estimated height of c 214m, it gives this hill a drop of c 22m.  The name of Berwyn is positioned near to the summit of this hill on larger scale Ordnance Survey maps.  However, there is a farm placed at SJ 205 222, that this name may apply to.


Pt. 212m    212m    SJ 112 135

With a 212m summit spot height, and a 191m bwlch spot height on the Ordnance Survey enlarged Geograph map, this hill has 21m of drop.  As no appropriate name is known for the hill the Pt. notation has been used.


Chirk Castle    c 212m    SJ 268 381

Excellent news – you can go to Chirk Castle and bag a Sub hill!  The summit of this hill is somewhere in the confines of Chirk Castle, it could well be in the tea room.  The bwlch contouring is between c 190m – c 195m and is estimated as c 191m, giving the hill c 21m of drop.  I wonder if the Trimble would pick up data in a tea room?


Pt. 298m    298m    SJ 032 139

As no appropriate name is known for this hill by the blog author it is another example where the Pt. notation is used.  The summit has a 298m spot height and the bwlch height is estimated as c 278m at SJ 024 140, giving a drop of c 20m.


Pt. c 291m    c 291m    SJ 067 162

The summit height has been estimated as c 291m as the hill has a small uppermost c 290m ring contour.  The bwlch has a 271m spot height at SJ 063 159 on the Ordnance Survey enlarged Geograph map, giving this hill a drop of c 20m.


Green Hall Hill    256m    SJ 156 192

With a summit spot height of 256m and an estimated bwlch height of c 236m, based on bwlch contouring of c 230m – c 240, this hill has c 20m of drop.




Next update due on the 16th June 2014

No comments: