Mapping Mountains – Summit Relocations – Y Pedwarau - The 400m Hills of Wales

Creigiau Cyrddau (SH 929 428)

There has been a Summit Relocation to a hill that is listed in the Y Pedwarau – The 400m Hills of Wales, with the summit height, bwlch height and their locations, the drop and status of the hill derived from a Trimble GeoXH 6000 survey conducted by Myrddyn Phillips and Aled Williams.

Creigiau Cyrddau (SH 929 428)

The criteria for the list that this summit relocation applies to are:

Y Pedwarau – The 400m Hills of Wales.  Welsh hills at or above 400m and below 500m in height that have 30m minimum drop, accompanying the main list are five categories of sub hills, with this hill being included in the 400m Sub-Pedwar category.  The criteria for this sub category being all Welsh hills at or above 400m and below 500m in height that have 20m or more and below 30m of drop.  The list is co-authored by Myrddyn Phillips and Aled Williams and is published on Mapping Mountains in Google Doc format.

Y Pedwarau - The 400m Hills of Wales by Myrddyn Phillips and Aled Williams

The name the hill is now listed by is Creigiau Cyrddau, and it is adjoined to the Carnedd y Filiast group of hills, which are situated in the central part of North Wales (Region C1, Sub-Region C1A), and it is positioned with the B4501 road to its north and west and a minor road and the A4212 road and the A494 road to south, and has the town of Y Bala towards the south.

When the original 400m height band of Welsh P30 hills compiled by Myrddyn Phillips was published on Geoff Crowder’s v-g.me website, this hill was included in the accompanying Hills to be surveyed sub list with a 497m summit height, based on the spot height that appears at SH 93067 42836 on the Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer map.  

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

After the sub list was standardised, and interpolated heights and drop values also included the details for this hill were re-evaluated and it was listed with 28m of drop, based on the 497m summit spot height and the 469m bwlch spot height that appears on the Ordnance Survey 1:25,000 Explorer map.  And these are the details the hill was listed by when the 1^st edition of the Y Pedwarau was published by Europeaklist in May 2013.

Since the original publication of the Welsh P30 lists on Geoff Crowder’s v-g.me website there have been a number of maps made available online.  Some of these are historic such as the series of Six-Inch maps on the National Library of Scotland website.  Whilst others were digitally updated such as the Ordnance Survey Vector Map Local hosted on the Geograph website and which was entitled the Interactive Coverage Map, whilst others are current and digitally updated such as the interactive mapping on the Magic Maps and WalkLakes websites.

The details for this hill were re-assessed when the Ordnance Survey Vector Map Local hosted on the Geograph website and which was entitled the Interactive Coverage Map became available online.  This mapping had many spot heights not on other publicly available Ordnance Survey maps and for this hill it had a 495m spot height positioned at SH 92974 42817.

Extract from the interactive mapping hosted on the WalkLakes website

The 495m spot height also appears on the WalkLakes interactive map that was originated from the Ordnance Survey Open Data programme.  Another resource now available online is the interactive mapping hosted on the Welsh Government website and entitled the DataMapWales.  This mapping has 5m contours and its detail matches that produced from the OS Terrain 5 product, which compliments much of that produced from LIDAR.  This mapping also gives a 495m summit spot height.

Extract from the DataMapWales

However, it was not until the Trimble GeoXH 6000 survey that the details for this hill could be accurately re-assessed.  The high point of the land where the 497m and the 495m spot heights appear on the ground were each surveyed with the following results:

497m spot height:  490.8m (converted to OSGM15) at SH 93066 42834

495m spot height:  494.6m (converted to OSGM15) at SH 92971 42820  

The Trimble GeoXH 6000 survey gives the highest ground on this hill as 494.6m positioned at SH 92971 42820, and this comes within the parameters of the Summit Relocations used within this page heading, these parameters are:

The term Summit Relocations applies when the high point of the hill is found to be positioned; in a different field, to a different feature such as in a conifer plantation,  within a different map contour either on Ordnance Survey maps or interactive mapping, to a different point where a number of potential summit positions are within close proximity, when natural ground or the natural and intact summit of a hill is confirmed compared to a higher point such as a raised field boundary or covered reservoir that is considered a relatively recent man-made construct, or the listing of a new twin summit or de-twinning of a summit, or a relocation of approximately 100 metres or more in distance from either the position of a map spot height or from where the summit of the hill was previously thought to exist.

Gathering data on the new listed summit position of Creigiau Cyrddau with Aled wearing a red top standing on the old listed summit position

Therefore, the height produced by the Trimble GeoXH 6000 survey to the summit of this hill is 494.6m and is positioned at SH 92971 42820.  This position is not given a spot height on the contemporary Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer map, and is approximately 104 metres westward from the position of the 497m map spot height.

The full details for the hill are:

Group:  Carnedd y Filiast

Name:  Creigiau Cyrddau

OS 1:50,000 map:  125

Summit Height:  494.6m (converted to OSGM15)

Summit Grid Reference (New Position):  SH 92971 42820 

     

Bwlch Height:  468.5m (converted to OSGM15)

Bwlch Grid Reference:  SH 93203 42714

Drop:  26.0m

Myrddyn Phillips and Aled Williams (October 2015)