Mapping Mountains – Summit Relocations – Y Pedwarau – The 400m Hills of Wales

Gwryd (SN 935 401)

There has been a Summit Relocation to a hill that is listed in the Y Pedwarau – The 400m Hills of Wales, with the summit height, bwlch height and their locations, the drop and status of the hill confirmed by LIDAR analysis conducted by Aled Williams.

LIDAR image of Gwryd (SN 935 401)

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

Y Pedwarau – The 400m Hills of Wales.  Welsh hills at or above 400m and below 500m in height that have 30m minimum drop, accompanying the main Y Pedwarau list are five categories of sub hills, with this hill listed in the 400m Sub-Pedwar category.  The criteria for 400m Sub-Pedwar status being all Welsh hills at or above 400m and below 500m in height that have 20m or more and below 30m of drop.  The list is co-authored by Myrddyn Phillips and Aled Williams and is published on Mapping Mountains in Google Doc format.

The name the hill is listed by is Gwryd and it is adjoined to the Mynydd Epynt group of hills, which are situated in the south-eastern part of Mid and West Wales (Region B, Sub-Region B2), and it is positioned with the A483 road to its north-west, the A40 road to its south and the B4520 road to its east, and has the small community of Capel Uchaf (Upper Chapel) towards the east.

When the 1^st edition of the Y Pedwarau was published by Europeaklist in May 2013 this hill was included in the 400m Sub-Pedwar category with 21m of drop based on the 453m summit height that appears as a spot height on the Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer map, and which is positioned at SN 93385 39742, and a 432m bwlch height that appears as a spot height on the Ordnance Survey 1:25,000 Explorer map.

Extract from the Ordnance Survey 1:25.000 Explorer map

The details for this hill were re-assessed when the Ordnance Survey Vector Map Local hosted on the Geograph website and which is entitled the Interactive Coverage Map became available online.  This mapping had many spot heights not on other publicly available Ordnance Survey maps and showed a 456m summit spot height for this hill positioned at SN 93588 40206.  This spot height is also shown on Ordnance Survey data that appears on the Magic Maps website.   

Extract from the Magic Maps website

However, it was not until LIDAR became available that the details for this hill could be accurately re-assessed.  The LIDAR (Light Detection & Ranging) technique produced highly accurate height data that is now freely available for much of England and Wales.

The LIDAR result for the 453m and 456m map heighted positions are given below:

453.6m at SN 93431 39769

456.2m at SN 93577 40195

The summit height produced by LIDAR analysis is 456.2m at SN 93577 40195, and this position in relation to that previously given comes within the parameters of the Summit Relocations used within this page heading, these parameters are:

The term Summit Relocations applies to any listed hill whose summit meets the following criteria; where there are a number of potential summit positions within close proximity and the highest point is not where previously given, 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, or when the summit of the hill is in a different field compared to where previously given, or when it is positioned to a different feature such as in a conifer plantation, or when the high point of the hill is placed within a different map contour compared to its previous listed position, or when natural ground or the natural and intact summit of a hill is confirmed compared to a higher point such as a raised field boundary that is judged to be a relatively recent man-made construct.

LIDAR image of the 456.2m summit positioned at SN 93577 40195

LIDAR image of the 453.6m southerly top positioned at SN 93431 39769

Therefore, the summit height produced by LIDAR analysis for this hill is 456.2m and is positioned at SN 93577 40195, this position is not given a spot height on contemporary Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer maps but matches the approximate position of the 456m spot height that now appears on the Magic Maps website, and is approximately 500 metres north north-eastward from where the previously listed summit is positioned.

ills of Wales, and are reproduced below@

The full details for the hill are:

Group:  Mynydd Epynt

Name:  Gwryd

OS 1:50,000 map:  160

Summit Height:  456.2m (LIDAR)

Summit Grid Reference (new position):  SN 93577 40195 (LIDAR) 

 

Bwlch Height:  433.1m (LIDAR)

Bwlch Grid Reference:  SN 93841 41671 (LIDAR)

Drop:  23.1m (LIDAR)

Myrddyn Phillips and Aled Williams (March 2020)