Mapping Mountains – Significant Name Changes – The Welsh P15s

Caer Glaw (SH 375 768) 

There has been a Significant Name Change to a hill that is listed in The Welsh P15s, with the summit height, bwlch height and their locations, the drop and status of the hill derived from detail on contemporary maps produced from Ordnance Survey data and LIDAR analysis conducted by Myrddyn Phillips. 

LIDAR bwlch image of Caer Glaw (summit at SH 375 768)

The criteria for the list that this name change applies to are:

The Welsh P15s – Welsh hills with 15m minimum drop, irrespective of their height, with an accompanying sub list entitled the Welsh Sub-P15s, with the criteria for this sub category being all Welsh hills with 14m or more and below 15m of drop.  The list is authored by Myrddyn Phillips, with the Introduction to the list appearing on Mapping Mountains on the 10^th May 2019. 

The Welsh P15s by Myrddyn Phillips

The hill is adjoined to the Ynys Môn group of hills, which are situated in the north-western part of North Wales (Region A, Sub-Region A1), and it is positioned with the coast to its west, the B5112 road to its north-west, the A5 and A55 roads to its south and a minor road to its immediate east, and has the village of Gwalchmai towards the east south-east. 

When the listing that became known as The Welsh P15s was being compiled, this hill was listed under the point (Pt. 63m) notation with 16m of drop, based on the 63m summit spot height that appears on the Ordnance Survey 1:25,000 Explorer map and the 47m bwlch spot height that appeared on the Ordnance Survey Vector Map Local hosted on the Geograph website and which was entitled the Interactive Coverage Map. 

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

As the summit of this hill comprises bounded land the details for it were examined on the Tithe map.  The term Tithe map is generally given to a map of a Welsh or English parish or township and which was prepared after the 1836 Tithe Commutation Act.  This act allowed tithes to be paid in cash rather than goods.  The Tithe maps gave names of owners and occupiers of land in each parish and importantly for place-name research they also included the name of enclosed land.  This enclosed land is usually based on a field system, however not every field is given a name, but many are and especially so in Wales. 

Extract from the Tithe map

The enclosed land where the summit of this hill is situated is given the number 17 on the Tithe map, this can be cross referenced against the apportionments; it is these apportionments that give the name of the owner or occupier of the land as well as the name of the land.  The land where the summit of this hill is situated is named as Caer Glaw in the apportionments, with the details on the Tithe map appearing in the parish of Llanbeulan and in the county named as Anglesey. 

Extract from the apportionments

Therefore, the name this hill is now listed by in The Welsh P15s is Caer Glaw and this derived from the Tithe map. 

 

The full details for the hill are: 

Group:  Ynys Môn 

Name:  Caer Glaw

Previously Listed Name:  Pt. 63m 

OS 1:50,000 map:  114

Summit Height:  63m (spot height) 

Summit Grid Reference:  SH 37576 76896 (spot height) 

Bwlch Height:  46.2m (LIDAR) 

Bwlch Grid Reference:  SH 38355 77966 (LIDAR) 

Drop:  17m (spot height summit and LIDAR bwlch) 

 

My thanks to Aled Williams for advice relating to the listed name of this hill

Myrddyn Phillips (October 2021)