Monday 21 July 2014

Hill Lists – Cymru / Wales – 200m Twmpau updates – Pumlumon



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 fifteenth Group is Pumlumon.



Pumlumon 

North of Aberystwyth at SN 579 808 and the Afon Rheidol to SN 749 807, continuing north of the Afon Castell to Eisteddfa Gurig at SN 797 841 and the Afon Tarrenig to SN 841 826 and the Afon Gwy (River Wye) to SN 910 792, continuing north of stream to bwlch at SN 927 800, continuing west of the Nant Gynwydd to SN 952 820 and the Afon Dulas to SN 945 838 and the Afon Hafren (River Severn) to SO 027 916, continuing south of the Afon Carno to bwlch at SN 930 998 and the Afon Laen to SH 890 027 and the Afon Twymyn to SH 821 052, and then the Afon Dyfi (River Dovey) to Bae Aberdyfi (Aberdovey Bay) and the sea at SN 592 945.  Bordering with the Tarennydd, Bryniau Dyfi, Mynydd y Cemaes and Carnedd Wen to the north, Pegwn Mawr and Garreg Lwyd to the east, Elenydd to the south and the sea to the west.  



Twmpau - 200m updates

Pt. 252m    252m    SN 797 954

A hill whose name has reverted to the Pt. notation as it was previously listed in the Sub list as Mynydd Rhiw-gam, which was partly invented from a wood to the west of the summit.  The bwlch contouring is between c 220m – c 230m, with the valley to valley contours being close together, implying a bwlch height of c 221m, giving this hill c 31m of drop.


Pt. 237m    237m    SN 809 977

This hill was originally listed as Penyglรดg, map study indicates that this name applies to the farm to the north-east of the summit.  The name of Cae’r Allt appears on the south-westerly slopes of this hill on Ordnance Survey maps, but as this name may apply to an enclosed field and not the hill or its summit, the name of the hill is reverting to the Pt notation.  The 237m summit height is taken from the Ordnance Survey enlarged Geograph map and the height of the bwlch has been estimated as c 203m from bwlch contouring between c 200m – c 210m, giving this hill c 34m of drop. 


Mynydd Cae-du    227m    SN 728 985

A hill whose promotion from the Sub list is reliant upon details from the Ordnance Survey enlarged Geograph map, as both summit and bwlch are spot heighted with 227m and 194m respectively, giving this hill 33m of drop.



Sub-Twmpau - 200m updates

Cefn Modfedd    289m    SN 788 972

This hill qualifies for the Sub list with an estimated c 26m of drop, based on a 289m summit height and an estimated c 263m bwlch height.  The area of the bwlch has a 264m spot height at SN 787 970 on the Ordnance Survey enlarged Geograph map positioned on a track, this has been judged too high and not at the critical bwlch.  However, saying that, the c 260m – c 270m contouring position suggests that this latter spot height is quite close to where the critical bwlch is positioned.



Pen yr Allt    267m    SH 842 025

Pen yr Allt has bwlch contouring between c 240m – c 250m, with the height of the bwlch estimated as c 242m, giving this hill c 25m of drop.



Pt. 246m    246m    SN 814 981

This hill follows the Pt. notation as the blog author does not know an appropriate name for it.  As the valley to valley contours are close together the bwlch height has been estimated as c 221m, based on bwlch contouring between c 220m – c 230m, giving this hill c 25m of drop.



Foel Fach    297m    SN 815 963

This hill is situated on the north-westerly descending ridge of Foel Fadian.  It has bwlch contouring between c 270m – c 280m with an estimated bwlch height of c 274m, giving this hill c 23m of drop.



Banc Troedrhiwseiri    233m    SN 671 854

A hill that has two uppermost c 230m ring contours, with the westerly one being 1m higher according to the map (the Ordnance Survey enlarged Geograph map gives the easterly ring contour a 232m spot height).  The OS enlarged Geograph map also spot heights the bwlch as 211m, this appears at a cross roads, the same position where a 212m spot height appears on the OS 1:50,000 map.  These values give this hill 22m of drop.



Castell Bwa-drain    298m    SN 712 794

Castell Bwa-drain is an ancient hill fort with commanding views over the Afon Rheidol, it qualifies for the Welsh 200 Sub-P30 list as it is given a height of 298m on Ordnance Survey maps and has bwlch contouring between c 270m – c 280m, with an estimated bwlch height of c 276m, giving this hill c 22m of drop.



Pt. 216m    216m    SN 729 978

A contentious entry in to the Sub list as it is based on the 216m summit spot height that appears on the Ordnance Survey enlarged Geograph map.  This spot height could be a typo as no c 210m ring contour exists; therefore the height may in fact be 206m.  However, for now the hill enters the Sub list.  It also has a twin 216m top at SN 731 981 that also suffers from a lack of a c 210m ring contour.  The bwlch contouring is between c 190m – c 200m and is estimated as c 194m at SN 731 982, with an alternate 194m bwlch height being positioned at SN 729 980.  If the 216m summit height is correct this hill has c 22m of drop. 



Pt. 208m    208m    SN 985 896

Another hill that follows the Pt. notation as the blog author does not know an appropriate name for it.  The bwlch contouring is between c 180m – c 190m with an estimated height of c 186m, giving this hill c 22m of drop. 



Pt. 273m    273m    SN 695 878

Although the name of Ffridd Cwmere appears near to the summit of this hill on some Ordnance Survey maps, the Pt. notation is being used for the name of the hill as the ffridd name may only apply to the bounded land to the west of the land where the summit of this hill is situated.  With a summit height of 273m and a bwlch height of 252m, the latter coming from the Ordnance Survey enlarged Geograph map, this hill has 21m of drop. 



Pt. 276m    276m    SN 717 788

The bwlch contouring for this hill is between c 250m - c 260m and is estimated as c 255m at SN 719 790, giving this hill a drop of c 21m.



Ffridd Rhosygarreg    297m    SN 806 947

With a summit height of 297m and an estimated bwlch height of c 277m, based on bwlch contouring between c 270m – c 280m, this hill has c 20m of drop.



Mynydd Eithaf    c 278m    SN 750 974

Another contentious entry as both summit and bwlch height have been estimated, and even after this the drop figure only comes to c 20m.  The bwlch contouring is between c 250m – c 260m and has been estimated as c 258m, whilst the summit height is estimated as c 278m based on the area of the uppermost contour ring compared to how close the ascending contour rings are to one another.



Cae’r Orseddan    223m    SN 805 998

This hill has bwlch contouring between c 200m – c 210m with the height of the critical bwlch estimated as c 203m, this gives the hill c 20m of drop.



Cefn Maesmawr Bach    217m    SN 727 981

Another hill that qualifies for the Sub list with c 20m of drop, based on a summit height of 217m and a bwlch height of c 197m, with bwlch contouring between c 190m – c 200m.



Next update due on the 28th July 2014


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