Myrddyn Phillips - Mapping Mountains: Mapping Mountains – Trimble Surveys

28.08.21 Stonewall Hill (SO 318 696)

Stonewall Hill (SO 318 696)

Stonewall Hill had previously been surveyed on the 17^th July, just over five weeks later and Aled and I were again back on its summit. We parked on the high narrow lane that skirts the border with England and headed back to its high point for more summit data. The reason for doing so was that the higher of two previous summit surveys came to 399.97m, just 3cm below 400m.

Stonewall Hill is one of two hills that are listed under the newly created status of National Top, each are now included in the Y Pedwarau – The 400m Hills of Wales list, the other being Hergest Ridge (SO 246 557). The concept of National Tops is explained in a separate post and for the lists co-authored with Aled Williams, this status affects just these two hills.

The summit of Stonewall Hill consists of a mound; its highest part has slight undulations but only comprises a small area. We debated whether three or five further surveys were sufficient. Four are documented and combined with the two previous surveys give six in all.

Once on the summit Aled prodded around and we quickly decided the approximate position for each survey. We then spent about 50 minutes hunkered below the survey equipment as it gathered one data set closely followed by another.

Gathering data at the summit of Stonewall Hill

We debated whether this was the most unusual Trimble survey to have taken place, as the hill is now a National Top, which is a new concept, this was a re-survey, it is positioned within a couple of minutes’ walk from a road and the summit is on top of a mound of unknown origin.

However, it is a good little top and has extensive views out toward the Clee Hills. Once all data sets were gathered and stored we headed back to the car. The processed result will tell us whether this hill makes it to the 400m height barrier!

Survey Result:

Stonewall Hill

Summit Height: 400.1m (converted to OSGM15) (400m Sub-Pedwar addition under National Top status) (significant height revision)

Summit Grid Reference: SO 31823 69655

Bwlch Height: 376.4m (converted to OSGM15, from previous Trimble GeoXH 6000 survey)

Bwlch Grid Reference: SO 31273 70279 (from previous Trimble GeoXH 6000 survey)

Drop: 23.8m

Dominance: 5.95%

For details on the 1^st summit survey of Stonewall Hill

For further details please consult the Trimble Survey Spreadsheet