Mapping Mountains – Trimble Surveys – Cefn yr Ystrad

 

06.06.23  Twyn yr Hyddod (SO 145 060) 

Twyn yr Hyddod (SO 145 060)

A day Pedwar bagging in the south Wales valleys with Mark, I started at a very leisurely pace with my head rested and eyes closed sitting in the front seat of my car whilst Mark visited the summit of Cadair Fawr (SN 977 123), a hill I had previously been up.  Although my eyes were closed for much of the time whilst I occasionally happily snoozed, I was still amazed at how fast cars seem to travel when passing a stationary object, they literally whizzed past on the minor road immediately in front of me as I opened an eye and stared out across a large expanse of grassland that disappeared toward the horizon with only the white flecks of a sheep or two to break the green monotony.

Once Mark was back from his first hill of the day he navigated us to the ridge above the Rhymni and Sirhywi valleys, it was here that the next two hills we planned on visiting were situated.  The first of which was Twyn yr Hyddod, which is a great bulk of a hill whose ascent is made easy if the convenience of its mountain road is taken, we took it, and I parked on the grass verge just below the high point of the road. 

Looking back toward the parking spot with the man-made hills of Twyn y Waun in the background on right

From the parking spot it was only a relatively short walk over copious amounts of bilberry up to the broad upper southerly ridge and then across to its crowning triangulation pillar.  However, before getting to the top I looked back beyond my car to the rows of terraced houses that make up the small community of Abertysswg, whose narrow road we had just driven on, on our way up the hill.  Beyond in the valley below were the houses of Rhymni and on the opposing side were the man-made hills of Twyn y Waun, which would be our last objective of the day. 

Approaching the summit of Twyn yr Hyddod

It was decidedly chilly on the ascent, so much so that when we reached the top Mark headed back down, leaving me to position the Trimble atop my rucksack and do all necessary things, such as noting the measurement offset between its internal antenna and the ground at its base and creating the file in the Trimble once the minimum of five satellites were logged on to.  All that remained was to wait until the 0.1m accuracy level was attained before data should be logged and then to stand back so as not to interfere with satellite reception whilst the allotted five minutes of data were gathered and stored.  During which I scribbled all necessary details in my surveying notebook. 

Gathering data at the summit of Twyn yr Hyddod

Once data were stored, I closed the equipment down, took a few photographs and packed it away and headed down, overshooting the direct descent which meant a slight double-back and a wander down the mountain road back to the car and the patiently waiting Mark, who was shielded from the chilled breeze whilst enjoying a bite to eat.  Twyn yr Hyddod proved a fine hill to start the day on. 

 

Survey Result:

 

Twyn yr Hyddod                       

Summit Height:  485.6m (converted to OSGM15, Trimble GeoXH 6000)

Summit Grid Reference:  SO 14515 06012 (Trimble GeoXH 6000)

Bwlch Height:  369.4m (LIDAR)

Bwlch Grid Reference:  SO 11880 10171 (LIDAR)

Drop:  116.2m (Trimble GeoXH 6000 summit and LIDAR bwlch)

Dominance:  23.93% (Trimble GeoXH 6000 summit and LIDAR bwlch)

 

 

For further details please consult the Trimble Survey Spreadsheet