Mapping Mountains – Summit Relocations – 30-99m Twmpau

Cae Benglog (SH 316 380)

There has been a Summit Relocation to a hill that is now listed in the 30-99m Twmpau, with the summit height and its position, drop and status of the hill confirmed by LIDAR analysis conducted by Myrddyn Phillips.

The criteria for this list are:

30-99m Twmpau – Welsh hills at and above 30m and below 100m in height that have a minimum 30m of drop, with an accompanying sub list entitled the 30-99m Sub-Twmpau with the criteria for this sub category being all Welsh hills at and above 30m and below 100m in height with 20m and more and below 30m of drop, with the word Twmpau being an acronym standing for thirty welsh metre prominences and upward. 

The name of the bounded land where the summit of this hill is situated is Cae Benglog with these details derived from the Tithe map and the hill is adjoined to the Pen Llŷn group of hills, which is situated in the north-west part of North Wales (Region A, Sub-Region A1), and is positioned overlooking the A 497 road which is to its north-east and has the small community of Morfa Nefyn t0 its north-west and the town of Pwllheli towards the south-east.

If wanting to visit the hill permission to do so should be sought as it is not a part of designated open access land, with the nearest public footpath close to the summit to its east.

This hill did not appear in the accompanying Hills to be surveyed sub list when the original Welsh P30 hills were published on Geoff Crowder’s v-g.me website as it did not meet the criteria for this sub category; however this sub list has now been standardised including the addition of interpolated drop values and heights.

Prior to LIDAR analysis this hill was listed with an estimated c 19m of drop based on the 86m spot height positioned at SH 31361 38368 on the Ordnance Survey 1:25,000 Explorer map and an estimated bwlch height of c 67m based on bwlch contouring at 5m intervals and between 65m – 70m on the Ordnance Survey Interactive Coverage Map hosted on the Geograph website.

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

Extract from OS Maps

The two positions of note and their heights relating to the summit of this hill were analysed via LIDAR resulting in the below:

86.779m at SH 31635 38073 (new summit position)

85.355m at SH 31355 38373 (position of 86m spot height and old listed summit)

The summit height produced by LIDAR analysis is 86.8m and is positioned at SH 31635 38073, this position is not given a spot height on contemporary Ordnance Survey maps although it does possess an uppermost 85m ring contour on the Ordnance Survey Interactive Coverage Map hosted on the Geograph website, whilst OS Maps show an 85m uppermost ring contour at the position of the LIDAR summit and an uppermost 80m ring contour at the position of the old summit, which is a more accurate representation of the height of this hill.  Therefore, the new summit position for this hill is approximately 350 metres south-eastward from the previously listed position.

LIDAR image of Cae Benglog

The full details for the hill are:

Group:  Pen Llŷn

Summit Height:  86.8m (LIDAR)

Name:  Cae Benglog

OS 1:50,000 map:  123

Summit Grid Reference (New Position):  SH 31635 38073 (LIDAR)  

 

Drop:  20.9m (LIDAR)

Myrddyn Phillips (April 2018)