Mapping Mountains – Trimble Surveys – Mynydd Twr

22.10.18  Bwrdd Arthur (SH 585 812)  

Bwrdd Arthur (SH 585 812)

Bwrdd Arthur is also known as Din Sylwy and is positioned overlooking the eastern coast of Ynys Môn.  The hill is designated a Site of Special Scientific Interest (SSSI) due to its limestone plateau giving rise to varied species of botanical interest.  The upper part of the hill is also designated open access land, whilst the remains of an ancient hill fort are situated on its northern slopes.  The latter is at least of Roman period if not older with two entrance ways still evident.

I approached the hill from the south having parked at the entrance to a near transmitting mast.  It was only a short walk down the continuation of the narrow road toward the start of a public footpath which made its way around the western part of the hill.

A path left this footpath and made its way up through gorse to a flat bedded grazing field with the encircling upper limestone on view just below the summit.  As the sun and cloud cast light and shade upon the hill I made my way to the far corner of the field where I imagined a path should be placed making its way up through the terraced limestone to the summit plateau.

Not surprisingly there was a path and it did as expected and strode out up through the limestone terrace to a grassed upper section where the trig pillar is placed.  However, a mound of blackthorn grew nearby and on-site visits had reported that a rock close to the edge of the blackthorn to be the high point of the hill, I found the rock but positioning the Trimble on it proved a little problematic as I wanted to give it elevation above its immediate nasty prickly surrounds, and using my rucksack as a makeshift tripod whilst balancing it on the narrow rock overlooking blackthorn hell was not the easiest.  However, somehow it remained in situ with the Trimble placed on top of it for the allocated ten minutes of data collection.

Gathering data at the summit of Bwrdd Arthur

The Trimble set-up position at the summit of Bwrdd Arthur

Once the Trimble had gathered and stored its allotted data I quickly closed it down, took a few photos and thankfully then packed it away.  It was now only a short walk retracing my inward route back to my awaiting car.

Survey Result:

Bwrdd Arthur 

Summit Height:  164.7m (converted to OSGM15, Trimble GeoXH 6000)

Summit Grid Reference:  SH 58577 81284 (Trimble GeoXH 6000)

Bwlch Height:  27.0m (LIDAR)

Bwlch Grid Reference:  SH 51561 77533 (LIDAR)

Drop:  137.8m (Trimble GeoXH 6000 summit and LIDAR bwlch)

Dominance:  83.63% (Trimble GeoXH 6000 summit and LIDAR bwlch)

For further details please consult the Trimble Survey Spreadsheet