Mapping Mountains – Trimble Surveys – Pumlumon

17.07.14  Bryn Rhosau (SN 733 799)

Bryn Rhosau (SN 733 799)

Towards the middle of July the summer is at its height, with luxuriant growth and when the weather has been favourable; dry earthen conditions.  Relatively low level hill walking can give fields full of grass, delicately swaying with any breath of breeze.  Visits to heath and moor can be enhanced with glimpses of gentle darting butterflies and rounded lambs confident in life as they look and run.  Today was such a day as early morning radiated a blue sky and warmth gave fulfilment.

Aled and I were on our second and last day of place-name enquiries, the first day was spent in the company of a Baroness and will hopefully be written about in a future blog post.  The second day was spent at the National Library of Wales (NLW) at Aberystwyth, an excellent centre for research.  On our way to NLW Aled had suggested visiting Bryn Rhosau which has a map height of 397m, quite close to the 400m height that would qualify the hill for Pedwar status.

As our priority was visiting NLW, hill walking time was limited, we therefore approached the hill from the south-west and parked at SN 729 797 where a car can be squeezed off the narrow winding lane between it and a track that heads up to one or two houses.  If time permitted an interesting route could be devised that takes in a number of P30’s either side of Llyn yr Oerfa.

The land that takes in Bryn Rhosau is a part of the Pumlumon range and is connected to Disgwylfa Fawr (SN 737 847) which is its Cardinal Hill.  The part of land we were visiting is the south-western extremity of the Pumlumon range and between us and the sea was a rolling landscape quickly descending to Capel Bangor and the Afon Rheidol.

We set off up the track at 8.30am and soon left its gravelled convenience and crossed a small ladder stile on our left that gave access on to open grassland, below us was Llyn yr Oerfa, one of many lakes in this area that gives good fishing.

Looking down on Llyn yr Oerfa

The narrow path continued heading north past reclaimed land adjacent to a house, whose manicured lawns and neatly arranged plantations looked rather unusual in such an open landscape.  The footpath led to open access land and a climb up the final higher slopes of the hill to its summit.

The view towards the north from the higher slopes of Bryn Rhosau

The summit area has two Bronze Age round barrows on it, the one to the north being the most pronounced and the higher, a marvellous place for our forbearers to construct such things, with expansive views in all directions.  I placed the Trimble on the highest point and set it to gather data, eight minutes later and with the data safely stored I closed the Trimble down and packed it away.

The higher of the two distinct Tumuli on the summit of Bryn Rhosau

Gathering data at the summit of Bryn Rhosau

The Trimble GeoXH 6000 on the summit of Bryn Rhosau

We re-traced our inward route and headed back to the car, arriving around 45 minutes after setting off.  Our next stop was the National Library of Wales to examine an Estate Survey Book from the 1790’s and many Tithe Maps, the former had extensive mapping for hill and lowlands and the latter confirmed a number of previously given names and gave many names that are unrecorded on any Ordnance Survey map.  All will be meticulously documented by Aled and will appear in future publications.

Approaching the car beside Llyn yr Oerfa

 

 

Survey Result:

Bryn Rhosau

Summit Height:  397.8m (converted to OSGM15, Trimble GeoXH 6000)  

Summit Grid Reference:  SN 73334 79996 (Trimble GeoXH 6000)

Bwlch Height:  c 314m (interpolation)

Bwlch Grid Reference:  SN 71822 81276 (interpolation)

Drop:  c 84m (Trimble GeoXH 6000 summit and interpolated bwlch)

Dominance:  21.07% (Trimble GeoXH 6000 summit and interpolated bwlch)

For further details please consult the Trimble survey spreadsheet click {here}