Mapping Mountains – Summit Relocations – 200m Twmpau

 

Pt. 212.2m (SJ 304 530) 

There has been a Summit Relocation to a hill that is listed in the 200m Twmpau, with the summit height, bwlch height and their locations, the drop and status of the hill derived from detail on contemporary maps produced from Ordnance Survey data and LIDAR bwlch analysis and a Trimble GeoXH 6000 summit survey conducted by Myrddyn Phillips. 

The summit field of Pt. 212.2m (SJ 304 530)

The criteria for the list that this summit relocation applies to are: 

200m Twmpau – Welsh hills at or above 200m and below 300m in height that have 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, with the word Twmpau being an acronym standing for thirty welsh metre prominences and upward. 

The 200m Twmpau by Myrddyn Phillips

The hill is being listed by the point (Pt. 212.2m) notation as an appropriate name for it either through local enquiry and / or historic research has not been found by the author, and it is adjoined to the Moel y Gamelin group of hills, which are situated in the north-eastern part of North Wales (Region A, Sub-Region A2), and it is positioned with the B5433 road to its north and minor roads to its west and south, and has the village of Bryn-teg towards the south. 

When the original 200m height band of Welsh P30 hills were published on Geoff Crowder’s v-g.me website, this hill was listed with a summit height of 211m based on the spot height that appears on the Ordnance Survey 1:25,000 Explorer map and which is positioned at SJ 301 537. 

Extract from the Ordnance Survey 1:25,000 Explorer map

Since publication of the P30 lists on Geoff Crowder’s v-g.me website there have been a number of Ordnance Survey maps made available online, some of these are historic such as the series of Six-Inch maps on the National Library of Scotland website, whilst others are current and digitally updated such as the old Ordnance Survey Vector Map Local hosted on the Geograph website and which was entitled the Interactive Coverage Map and the interactive mapping available on the Magic Maps and WalkLakes websites. 

The details for this hill were re-assessed when the Ordnance Survey Vector Map Local hosted on the Geograph website and which was entitled the Interactive Coverage Map became available online.  This mapping had many spot heights not on other publicly available maps and for this hill it had a 213m summit spot height positioned at SJ 30407 53076, this is 2m higher than the previously listed summit height of 211m, and this comes within the Summit Relocations used within this page heading, and these parameters are: 

The term Summit Relocations applies to when the high point is positioned in a different field, to a different feature such as a conifer plantation, within a different map contour, a different point where a number of potential summit positions are within close proximity, when natural ground or the natural and intact summit is confirmed compared to a higher point such as a raised field boundary or covered reservoir that is considered a relatively recent man-made construct, or a relocation of approximately 100 metres or more in distance from either the position of a map spot height or from where the summit of the hill was previously thought to exist. 

The Trimble GeoXH 6000 gathering data at the summit of Pt. 212.2m (SJ 304 530)

Therefore, the summit height produced by the Trimble GeoXH 6000 survey is 212.2m with the same 212.191m height produced at two different positions at SJ 30413 53067 and SJ 30417 53061, these positions are not given a spot height on the contemporary Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer map but do match the approximate position of the 213m spot height that appeared on the Ordnance Survey Vector Map Local hosted on the Geograph website and which was entitled the Interactive Coverage Map, and they are approximately 650 metres southward from where the previously listed summit is positioned.

 

ills of Wales, and are reproduced below@

The full details for the hill are: 

Group:  Moel y Gamelin 

Name:  Pt. 212.2m 

OS 1:50,000 map:  117

Summit Height:  212.2m (converted to OSGM15, Trimble GeoXH 6000) 

Summit Grid Reference (New Position):  SJ 30413 53067 & SJ 30417 53061 (Trimble GeoXH 6000) 

Bwlch Height:  176.9m (LIDAR) 

Bwlch Grid Reference:  SJ 29817 53587 (LIDAR) 

Drop:  35.3m (Trimble GeoXH 6000 summit and LIDAR bwlch) 

 

Myrddyn Phillips (December 2021)