Mapping Mountains – Significant Height Revisions – The Welsh Highlands – Uchafion Cymru

Great Creigiau (SO 198 636) 

There has been a Significant Height Revision to a hill that was considered for inclusion in the list of The Welsh Highlands – Uchafion Cymru, with the summit height, bwlch height and their locations, the drop and status of the hill derived from a Trimble GeoXH 6000 survey conducted by Myrddyn Phillips and Aled Williams. 

Great Creigiau (SO 198 636)

The criteria for the list that this height revision applies to are: 

The Welsh Highlands – Uchafion Cymru – This is the revised draft title for the Welsh 500m P15s list that takes in all hills in Wales at or above 500m in height with 15m minimum drop.  Accompanying the main list are three sub lists, these are; 500m Sub-Uchaf, 490m Sub-Uchaf and the Double Sub category, with this hill being considered for 500m Sub-Uchaf satus.  The criteria for which are all Welsh hills at or above 500m in height with 14m or more and below 15m of drop.  The list is co-authored by Myrddyn Phillips and Aled Williams with the Introduction to the list being published on Mapping Mountains in November 2015 and an update relating to the list appearing on Mapping Mountains on the 19^th June 2019.

The Welsh Highlands - Uchafion Cymru by Myrddyn Phillips and Aled Williams

The name the hill is listed by is Great Creigiau and it is adjoined to the Fforest Glud group of hills, which are situated in the eastern part of Mid and West Wales (Region B, Sub-Region B1), and it is positioned with the A488 road to its north, the A44 road to its south and the B4372 road to its south-east, and has the village of Maesyfed (New Radnor) towards the south south-east. 

This hill was not included as a P14 Sub in the original list of Welsh 500m P15s that later became known as Yr Uchafion and latterly as The Welsh Highlands – Uchafion Cymru, as with a 646m summit spot height and bwlch contouring between 630m – 640m that appear on the Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer map, this contouring implied that the hill did not have sufficient drop to be considered for P14 500m Sub-Uchaf status. 

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

The summit of this hill has now been surveyed with the Trimble GeoXH 6000, resulting in 643.4m positioned at SO 19810 63643 and this height comes within the parameters of the Significant Height Revisions used within this page heading, these parameters are: 

The term Significant Height Revisions applies to any listed hill whose interpolated height and Ordnance Survey or Harvey map summit spot height has a 2m or more discrepancy when compared to the survey result produced by the Trimble GeoXH 6000 or analysis of data produced via LIDAR, also included are hills whose summit map data is missing an uppermost ring contour when compared to the data produced by the Trimble or by LIDAR analysis. 

The Trimble GeoXH 6000 gathering data at the summit of Great Creigiau

Therefore, this hill’s new listed summit height is 643.4m and this was derived from a Trimble GeoXH 6000 survey, this is positioned at SO 19810 63643 and is 2.6m lower than its previously listed height of 646m which appears as a spot height on contemporary Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer maps.

 

ills of Wales, and are reproduced below@

The full details for the hill are:

Group:  Fforest Glud

Name:  Great Creigiau

OS 1:50,000 map:  148

Summit Height (New Height):  643.4m (converted to OSGM15)

Summit Grid Reference:  SO 19810 63643  

Bwlch Height:  633.3m (converted to OSGM15)

Bwlch Grid Reference:  SO 19959 63879

Drop:  10.1m

 

Myrddyn Phillips and Aled Williams (August 2021)