Hill Reclassifications - 200m Twmpau

This part of the Mapping Mountains blog is dedicated to any hill reclassification for the listings I have compiled.  These include ones found from map detail as well as those from accurate surveying.

There have been a number of recent new entries to the Welsh 200m P30 list, including some that do not appear in other P30 listings.  The following are those for Mynydd Hiraethog:

Mynydd Hiraethog             Ffridd y Mynydd    258m    SH 825 758

A promotion from the sub-list and summit relocation as this hill was originally listed as c 250m at SH 826 753 (SH 825 753).  There are eleven separate contour rings at c 250m in the vicinity of the high point of this hill, but only one has an uppermost c 255m ring contour on the Ordnance Survey enlarged mapping on the Geograph website.  The same ring contour has an old imperial height of 847ft (258.2m) on the Ordnance Survey Historical 1:25,000 map.  The bwlch contouring is between c 220m – c 225m and the critical bwlch is estimated as c 223m, giving this hill c 35m of drop. 

Mynydd Hiraethog             Pt. 258m    258m    SH 811 542

Since drop values were added to the list this hill has been listed with c 30m of prominence.  It appeared under an invented name of Bryn Graeanllyn but has now converted to the Pt. notation.  It has a twin summit at SH 810 544, it is hoped that a Trimble survey can soon separate these summits.  The survey took place and de-twinned the two summits and deleted the higher summit from the P30 list.

To see the results of a Trimble survey of this hill click {here}

Mynydd Hiraethog             Dinas Mawr    254m    SH 808 539

This hill is adjacent to the twin summits at SH 811 542 and SH 810 544 and will soon be surveyed with the Trimble GeoXH 6000 to confirm (or otherwise) its inclusion in the Welsh 200m P30 list.  Until then it is promoted from the sub-list as bwlch contouring on current maps is between c 220m – c 230m and suggests a height of c 224m, giving this hill a drop of c 30m.  The Ordnance Survey enlarged mapping on the Geograph website has a 221m spot height on the area of the bwlch at SH 809 539 but as it is not centred on the hill to hill traverse it has not been used for drop evaluation.  

To see the results of a Trimble survey of this hill click {here}

Mynydd Hiraethog             Pt. 253m    253m    SH 940 639

Another promotion from the sub-list as the Ordnance Survey enlarged mapping on the Geograph website has a 253m spot height on the area of the summit and as bwlch contouring is between c 220m – c 225m and estimated as c 223m, it gives this hill c 30m of drop.  The hill was listed as Bryn Gwern-llifion which was an invented name; it has now converted to the Pt. notation.     

Mynydd Hiraethog             Pt. 211m    211m    SJ 060 618

This hill used to be listed in the sub-list with c 29m of drop under the name of Bryn Llewesog.  The summit contouring has been re-evaluated giving this hill c 30m of drop.  The Pt. notation has now been used for its name as the previously listed name was an invented one.  The name of Pen-y-cae appears on current Ordnance Survey maps and has been used in other P30 listings, but map study implies this name relates to the buildings at SJ 065 622 and not to the hill itself.  The name of Coed y Plas appears on the Ordnance Survey enlarged mapping on the Geograph website for the wood on this hill’s southern flank, this may be the locally known name of the hill, but as the wood does not reach the summit, the name has not been used until further investigation can take place. 

There have also been a number of ‘new’ subs that have entered the Welsh 200m P30 listing for Mynydd Hiraethog, these are:

Mynydd Hiraethog            Mynydd y Gyrt    298m    SH 967 693

The area of the bwlch has a 274m spot height at SH 969 690 on the large scale Ordnance Survey mapping on the Geograph website, this gives the hill 24m of drop.

Mynydd Hiraethog            Pt. c 216m    c 216m    SJ 009 646

The critical bwlch may well be situated in someone’s living room in the small community of Groes Fawr!  The summit is estimated as c 216m from an uppermost c 215m ring contour on the Ordnance Survey enlarged mapping on the Geograph website.  The bwlch contouring is between c 190m – c 195m and is estimated as c 192m, giving this hill c 24m of drop.

Mynydd Hiraethog            Coed y Fron    274m    SJ 051 446

The valley to valley contours are placed so close to one another the bwlch height is estimated to be c 251m, with the bwlch contouring between c 250m – c 260m.  With a spot height on the area of the summit of 274m it gives this hill c 23m of drop.  The name of Coed y Fron has been used as larger scale maps indicate that the wood just takes in the summit.

Mynydd Hiraethog            Pt. 265m    265m    SH 999 646

The summit height for this hill comes from the old imperial height of 868ft (264.6m) on the Ordnance Survey Historical 1:25,000 and the New Popular One-Inch maps.  The 868ft height also appears on a number of 1:10,560 maps.  The area of the bwlch has a 243m spot height at SH 996 647 on the large scale Ordnance Survey mapping on the Geograph website, giving this hill 22m of drop.

Mynydd Hiraethog            Pt. 213m    213m    SH 817 637

The bwlch contouring is between c 190m – c 195m with the critical bwlch estimated to be c 192m, giving this hill c 21m of drop.

Mynydd Hiraethog            Pt. 227m    227m    SJ 019 447

The area of the bwlch has a 207m spot height at SJ 020 448 on the large scale Ordnance Survey mapping on the Geograph website, this gives the hill 20m of drop.

Mynydd Hiraethog            Pt. 203m    203m    SH 821 740

The bwlch contouring has 5m intervals on the Ordnance Survey enlarged mapping on the Geograph website.  The contours are between c 180m – c 185m, with the critical bwlch estimated as c 183m, giving this hill c 20m of drop.

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