Mapping Mountains – Hill Reclassifications – Y Trechol – The Dominant Hills of Wales

Pandy Bank (SJ 336 538) – Lesser Dominant addition

There has been an addition to the list of the Y Trechol – The Dominant Hills of Wales, with the summit height and it location confirmed by a Trimble GeoXH 6000 survey conducted by Myrddyn Phillips on the 5^th April 2016, and the bwlch height and its location, the drop, dominance and status of the hill confirmed by LIDAR analysis initially conducted by Chris Crocker and subsequently by Myrddyn Phillips.

Pandy Bank (SJ 336 538)

The criteria for the list that this addition applies to are:

Y Trechol - The Dominant Hills of Wales - Welsh P30 hills whose prominence  equal or exceed half that of their absolute height.  With the criteria for Lesser Dominant status being those additional Welsh P30 hills whose prominence is between one third and half that of their absolute height, with the Introduction to the Mapping Mountains publication of this list appearing on the 3^rd December 2015, and the list is now available in its entirety on Mapping Mountains in Google Doc format.

The name the hill is Pandy Bank and it is adjoined to the Bryniau Clwyd group of hills, which are situated in the north-eastern part of North Wales (Region A, Sub-Region A2), and it is positioned with the B5425 road to its west and the A483 road to its east with the Afon Alun (River Alyn) to its west and east, and has the town of Wrecsam (Wrexham) towards the south.

When the original 100m height band of Welsh P30 hills were published on Geoff Crowder’s v-g.me website this hill was not included in the main P30 list as contemporary Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer maps of the day did not give the hill any contours of note.  The hill is the bi-product of mine spoil deposited from the Gresford Colliery and therefore the practice used in these two mapping scales is to show such land as a blank space on the map. 

Extract from the Ordnance Survey 1:25,000 Explorer map

The details for this hill were re-examined when the Ordnance Survey Vector Map Local hosted on the Geograph website and which is entitled the Interactive Coverage Map became available online.  This mapping has many spot heights not on other publicly available Ordnance Survey maps, and for the area taking in this hill it has contours at 5m intervals with an uppermost contour of 105m and bwlch contouring between 70m – 75m, with interpolation giving this hill an estimated c 34m of drop.

Extract from the Ordnance Survey Vector Map Local hosted on the Geograph website and which is entitled the Interactive Coverage Map

The details on the Ordnance Survey Vector Map Local prompted a survey conducted with the Trimble GeoXH 6000, resulting in a 105.4m summit height and when coupled with an estimated bwlch height of c 71m it gave this hill c 34m of drop and 32.61% dominance.

However, it was not until LIDAR became available that the details for the bwlch of this hill could be accurately re-assessed.  The LIDAR (Light Detection & Ranging) technique produced highly accurate height data that is now freely available for much of England and Wales. 

LIDAR image of Pandy Bank

Therefore, the addition of Pandy Bank to Lesser Dominant status is due to LIDAR bwlch analysis coupled with a Trimble GeoXH 6000 summit survey, resulting in a 105.4m summit height positioned at SJ 33630 53882 and a 70.2m bwlch height positioned at SJ 33704 53783, with these values giving this hill 35.1m of drop and 33.34% dominance, which is sufficient for Lesser Dominant status.

The full details for the hill are:

Group:  Bryniau Clwyd

Name:  Pandy Bank

OS 1:50,000 map:  117

Summit Grid Reference:  SJ 33630 53882

Summit Height:  105.4m (converted to OSGM15)

Bwlch Grid Reference:  SJ 33704 53783 (LIDAR)

Drop Summit to Bwlch:  35.1m (Trimble summit and LIDAR bwlch)

Drop Bwlch to ODN:  70.2m (LIDAR)

Dominance:  33.34% (Trimble summit and LIDAR bwlch)

For details on the summit survey of Pandy Bank

Myrddyn Phillips (December 2019)