Friday, 7 August 2015

Mapping Mountains – Significant Height Revisions – 300m Twmpau

Old Radnor Hill (SO 251 587)

This is the first post under the heading of Significant Height Revisions, and the following details are retrospective as the Trimble survey that resulted in this height revision was conducted on 11th January 2014.

The first major height revision initiated from a survey with the Trimble GeoXH 6000 was conducted in the southern part of Fforest Glud, otherwise known as the Radnor Forest, in the heartland of mid Wales on a fine and bright winter’s day.

The hill is listed in the 300m height band of Twmpau hills and is situated south-east of Maesyfed (New Radnor), with the nearest major road to the hill being the A44 which skirts the hill on its northern and eastern side, and by doing so this road significantly alters this hill’s drop as the natural bwlch no longer exists as it was once situated inside what is now an old Chapel, with the A44 cutting to the east of the hill now the position of its critical bwlch.

The name of the hill is Old Radnor Hill; its summit height has been dramatically decreased over time due to it being quarried.  However, prior to the survey with the Trimble GeoXH 6000 its listed height was c 317m based on the uppermost contour on current Ordnance Survey enlarged mapping on the Geograph website showing part of a 315m contour ring.

Its new summit height is 312.6m, which is 4.6m lower than its previously estimated listed height and 2.4m lower than the 315m uppermost ring contour on the enlarged Geograph map.

The full details for the hill are:

Cardinal Hill:  Gwaun Ceste

Summit Height (New Height):  312.6m (converted to OSGM15)

Name:  Old Radnor Hill

OS 1:50,000 map:  148

Summit Grid Reference:  SO 25135 58770
Drop:  97.1m

The quarried remains of Old Radnor Hill

For details on the survey that significantly revised the summit height of this hill please click {here}

Myrddyn Phillips (January 2014)

No comments: