Bache Hill – a question finally answered

Bache Hill is one of the highest hills in Radnorshire and makes a good circuit when combined with its two near and slightly higher neighbours of Black Mixen and Great Rhos.  Its summit area consists of heather, with a conifer plantation to its north and reclaimed grazing land to its south.

Bache Hill from the ascent toward Black Mixen

The hill is given a 610m summit spot height on contemporary Ordnance Survey maps.  This is to a triangulation pillar that has a 610.209m flush bracket height.  The hill is rather unassuming, but its main redeeming feature is its ancient tumulus which the trig pillar is positioned on top of.  The tumulus was built in the Bronze Age approximately 5,000 years ago and I had previously surveyed its height from base to top with my old basic levelling staff as approximately 9ft (2.7m). 

The ancient tumulus atop Bache Hill

Therefore, ground at the base of the tumulus would be approximately 607m in height.  However, having visited this hill on 21 previous occasions I was aware that ground amongst the heather to the west of the tumulus looked as if it was rising and if so this would mean that the natural summit of the hill was intact.  Because of this Bache Hill had long been on the surveying agenda. 

1st survey at western base of tumulus with rising ground centre background of photo indicating the position of the natural summit of the hill 

This hill is classified as a Hewitt, Nuttall, Simm, Uchaf, 600m Twmpau and Tump.  But the ramifications of the survey only had potential impact upon its Hewitt and Nuttall status, but dependent upon the height of the remaining natural summit and the thoughts of the respective hill list authors the outcome may also impact upon the Dewey listing. 

2nd survey at northern base of tumulus

The survey of Bache Hill was conducted with Aled Williams on the 27^th May in excellent conditions with warm sunshine, good visibility and no breeze. 

Four data sets from the base of the tumulus were gathered, each 90° from one another.  This would give a good spread of height and indicate where the higher and lower ground met the tumulus. 

5th survey at the high point of the tumulus

One data set was gathered from the high point of the tumulus which is about one metre from the base of the trig pillar. 

A further data set was gathered just to the north-west of the tumulus on rising ground. 

And a further two data sets were gathered westward of the tumulus about 100 metres from it.  It was here that we considered the natural summit of the hill to be positioned.

8th survey in the vicinity of the natural summit

The results appear below:

 

Base of tumulus:

1^st survey:  607.869m at SO 21377 63648

2^nd survey:  607.608m at SO 21392 63653

3^rd survey:  607.024m at SO 21397 63642

4^th survey:  607.278m at SO 21382 63635

 

Although the base of the tumulus undulates, the position of the first survey indicates ground on its western side is the highest and ground on its eastern side the lowest.  This confirms what we thought when standing beside the trig pillar as ground to our east gradually descended, whereas ground to our west definitely went uphill.

 

Top of tumulus:

5^th survey:  610.121m at SO 21386 63643

 

To the north-west of Tumulus:

6^th survey:  608.416m at SO 21353 63662

 

100 metres to west of Tumulus:

7^th survey:  610.094m at SO 21281 63610

8^th survey:  609.904m at SO 21271 63605

 

Conclusion:

The 7^th and 8^th surveys complement each other and confirm the natural summit of this hill is intact and is at, or in the vicinity of grid reference SO 21281 63610.

The measurement offset for the 7^th and 8^th surveys was taken down to the base of the heather in the peat.  However, you could easily go down a few more centimetres if so inclined, but you would have to go down a further 0.487m (about 1½ft) for this part of the hill to be below 609.6m, this confirms the natural summit is intact and is over 2,000ft (609.6m) in height.

Lastly, the Trimble result gives the 7^th survey as only 0.027m below the high point of the tumulus.  That a natural summit exists and its position west of the tumulus was not a surprise, but its height being so close to that of the tumulus was.

Bache Hill can again rest in peace in the knowledge that it retains its 2,000ft status, both to its ancient tumulus and now also confirmed to its natural summit.

Myrddyn Phillips (June 2021)