Mapping Mountains – Hill Reclassifications – 100m Twmpau

Cae Cefn (ST 059 748) – 100m Twmpau deletion

There has been a deletion of a hill that was listed in the 100m Twmpau, with the summit height and its location confirmed by a Leica GS15 survey conducted by John Barnard, Graham Jackson and Myrddyn Phillips which took place on the 4^th November 2013, and the bwlch height and its location, the drop and status of the hill confirmed by LIDAR analysis conducted by Myrddyn Phillips.

LIDAR image of Cae Cefn (ST 059 748)

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

100m Twmpau - Welsh hills at or above 100m and below 200m in height with 30m minimum drop, with an accompanying sub list entitled the 100m Sub-Twmpau with the criteria for this sub category being all Welsh hills at or above 100m and below 200m in height with 20m or more and below 30m of drop, with the word Twmpau being an acronym standing for thirty welsh metre prominences and upward.

The name the hill is now listed as is Cae Cefn and this derived from the Tithe map, and it is adjoined to the Bro Morgannwg group of hills, which are situated in the southern part of South Wales (Region C, Sub-Region C2), and it is positioned with the A48 road to its south-east and minor roads to its west, north and east, and has the city of Caerdydd (Cardiff) towards the east and the town of Y Bont-faen (Cowbridge) to the west.

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

Extract from the Ordnance Survey Vector Map Local hosted on the Geograph website

When the original 100m height band of Welsh P30 hills were published on Geoff Crowder’s v-g.me website this hill was listed with a 140m summit height based on the spot height that appears on the Ordnance Survey 1:25,000 Explorer map.  However, as the 140m spot height is placed at the top of a covered reservoir and as these structures are considered recent man-made constructs and as Tair Onnen vied for being the higher hill, both hills were surveyed using a Leica GS15, resulting in:

Cae Cefn (ST 05910 74886):  136.2m (natural ground at base of covered reservoir)

Tair Onnen (ST 03660 73979):  137.3m

When LIDAR became available the details for these two hills were re-assessed.  The LIDAR (Light Detection & Ranging) technique produced highly accurate height data that is now freely available for much of England and Wales.  The LIDAR summit details are given below:

Cae Cefn (ST 05915 74885):  136.4m (natural ground at base of covered reservoir)

Tair Onnen (ST 03661 73979):  137.4m 

  

The Leica GS15 gathering data at the summit of Cae Cefn

Therefore, the deletion of Cae Cefn from 100m Twmpau status is due to a Leica GS15 summit survey, resulting in a 136.2m summit height taken to natural ground at the base of the man-made covered reservoir as opposed to the 137.3m summit height for Tair Onnen, and a 116.25m bwlch height from LIDAR analysis, with these values giving Cae Cefn 19.9m of drop which is insufficient for this hill to be classified as a 100m Twmpau.

The full details for the hill are:

Group:  Bro Morgannwg

Name:  Cae Cefn

OS 1:50,000 map:  170

Summit Height:  136.2m (Leica GS15)

Summit Grid Reference:  ST 05910 74886 (Leica GS15)

Bwlch Height:  116.25m (LIDAR)

Bwlch Grid Reference:  ST 04273 74542 (LIDAR)

Drop:  19.9m (Leica GS15 summit and LIDAR bwlch)

Myrddyn Phillips (October 2019)

Mapping Mountains – Significant Height Revisions – 100m Twmpau

Cae Cefn (ST 059 748)

There has been a Significant Height Revision to a hill that was listed in the 100m Twmpau, with the summit height and its location confirmed by a Leica GS15 survey conducted by John Barnard, Graham Jackson and Myrddyn Phillips which took place on the 4^th November 2013, and the bwlch height and its location, the drop and status of the hill confirmed by LIDAR analysis conducted by Myrddyn Phillips.

The Leica GS15 gathering data at the summit of Cae Cefn

The criteria for the list that this height revision applies to are:

100m Twmpau - Welsh hills at or above 100m and below 200m in height with 30m minimum drop, with an accompanying sub list entitled the 100m Sub-Twmpau with the criteria for this sub category being all Welsh hills at or above 100m and below 200m in height with 20m or more and below 30m of drop, with the word Twmpau being an acronym standing for thirty welsh metre prominences and upward.

LIDAR image of Cae Cefn (ST 059 748)

The name the hill is now listed as is Cae Cefn and this derived from the Tithe map, and it is adjoined to the Bro Morgannwg group of hills, which are situated in the southern part of South Wales (Region C, Sub-Region C2), and it is positioned with the A48 road to its south-east and minor roads to its west, north and east, has the city of Caerdydd (Cardiff) towards the east and the town of Y Bont-faen (Cowbridge) to the west.

When the original 100m height band of Welsh P30 hills were published on Geoff Crowder’s v-g.me website this hill was listed with a 140m summit height based on the spot height that appears on the Ordnance Survey 1:25,000 Explorer map.  However, as the 140m spot height is placed at the top of a covered reservoir and as these structures are considered recent man-made constructs and as Tair Onnen vied for being the higher hill, both hills were surveyed using a Leica GS15, resulting in:

Cae Cefn (ST 05910 74886):  136.2m (natural ground at base of covered reservoir)

Tair Onnen (ST 03660 73979):  137.3m

When LIDAR became available the details for these two hills were re-assessed.  The LIDAR (Light Detection & Ranging) technique produced highly accurate height data that is now freely available for much of England and Wales.  The LIDAR summit details are given below:

Cae Cefn (ST 05915 74885):  136.4m (natural ground at base of covered reservoir)

Tair Onnen (ST 03661 73979):  137.4m

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

Extract from the Ordnance Survey Vector Map Local hosted on the Geograph website

The height produced by the Leica GS15 survey is 136.2m and is positioned at ST 05910 74886, this revised height comes within the parameters of the Significant Height Revisions used within this page heading, these parameters are:

The term Significant Height Revisions applies to any listed hill whose interpolated height and Ordnance Survey or Harvey map summit spot height has a 2m or more discrepancy when compared to the survey result produced by the Trimble GeoXH 6000, or other GNSS equipment, or analysis of data produced via LIDAR, also included are hills whose summit map data is missing an uppermost ring contour when compared to the data produced by the Trimble or by LIDAR analysis.

Therefore, this hill’s new listed summit height is 136.2m and this is to natural ground at the base of a covered reservoir and positioned at ST 05910 74886,  this is 3.8m lower than the previously listed summit height of 140m which was based on the spot height that appears on the Ordnance Survey 1:25,000 Explorer map.

 ills of Wales, and are reproduced below@

The full details for the hill are:

Group:  Bro Morgannwg

Name:  Cae Cefn

OS 1:50,000 map:  170

Summit Height (New Height):  136.2m (Leica GS15)

Summit Grid Reference:  ST 05910 74886 (Leica GS15)

Bwlch Height:  116.25m (LIDAR)

Bwlch Grid Reference:  ST 04273 74542 (LIDAR)

 

Drop:  19.9m (Leica GS15 summit and LIDAR bwlch)

Myrddyn Phillips (October 2019)

Mapping Mountains – Significant Name Changes – 100m Twmpau

Cae Cefn (ST 059 748)

There has been a Significant Name Change to a hill that was listed in the 100m Twmpau, with the summit height and its location confirmed by a Leica GS15 survey conducted by John Barnard, Graham Jackson and Myrddyn Phillips which took place on the 4^th November 2013, and the bwlch height and its location, the drop and status of the hill confirmed by LIDAR analysis conducted by Myrddyn Phillips.

The Leica GS15 gathering data at the summit of Cae Cefn

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

100m Twmpau - Welsh hills at or above 100m and below 200m in height with 30m minimum drop, with an accompanying sub list entitled the 100m Sub-Twmpau with the criteria for this sub category being all Welsh hills at or above 100m and below 200m in height with 20m or more and below 30m of drop, with the word Twmpau being an acronym standing for thirty welsh metre prominences and upward.

LIDAR image of Cae Cefn (ST 059 748)

The hill is adjoined to the Bro Morgannwg group of hills, which are situated in the southern part of South Wales (Region C, Sub-Region C2), and it is positioned with the A48 road to its south-east and minor roads to its west, north and east, has the city of Caerdydd (Cardiff) towards the east and the town of Y Bont-faen (Cowbridge) to the west.

The hill appeared in the original Welsh 100m P30 list on Geoff Crowder’s v-g.me website under the transposed name of Lillypot, without any accompanying note implying that I didn’t even realise that this name was not that of the hill.

Lillypot

140m

ST059749

170

151

Clem/Yeaman substituting Pan y Lladron at 037740.

During my early hill listing I thought it appropriate to either invent a name for a hill, or use a name that appeared near to the summit of the hill on Ordnance Survey maps of the day.  My preference was to use farm names and put Pen, Bryn or Moel in front of them or as in this instance transpose the name of what I later realised is that of a farm and use it for the hill.  This is not a practice that I now advocate as with time and inclination place-name data can be improved either by asking local people or by examining historic documents, through this form of research an appropriate name for the hill can usually be found.

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

Extract from the Ordnance Survey Vector Map Local hosted on the Geograph website

As this hill comprises bounded land the Tithe map was consulted.  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 832 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 Cae Cefn in the apportionments, with the details on the Tithe map appearing in the parish of Pendoylan and in the county named as Glamorgan.

Extract from the apportionments

Therefore, the name this hill is documented by and would have been listed in the 100m Twmpau if its drop was sufficient is Cae Cefn, and this was derived from the Tithe map.

The full details for the hill are:

Group:  Bro Morgannwg

Name:  Cae Cefn

Previously Listed Name:  Lillypot

 

OS 1:50,000 map:  170

Summit Height:  136.2m (Leica GS15)

Summit Grid Reference:  ST 05910 74886 (Leica GS15)

Bwlch Height:  116.25m (LIDAR)

Bwlch Grid Reference:  ST 04273 74542 (LIDAR)

 

Drop:  19.9m (Leica GS15 summit and LIDAR bwlch)

Myrddyn Phillips (October 2019)

Mapping Mountains – Summit Relocations – Y Trechol – The Dominant Hills of Wales

Tair Onnen (ST 036 739)

LIDAR image of Tair Onnen (ST 036 739)

There has been a Summit Relocation to a hill that is listed in the Y Trechol – The Dominant Hills of Wales, with the summit height and its location confirmed by a Leica GS15 survey conducted by John Barnard, Graham Jackson and Myrddyn Phillips which took place on the 4^th November 2013.

The criteria for the list that this summit relocation 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.  The list is authored by Myrddyn Phillips with the Introduction to the start of the Mapping Mountains publication of this list appearing on the 3^rd December 2015.

The name of the hill is Tair Onnen, and it is adjoined to the Bro Morgannwg group of hills, which are situated in the southern part of South Wales (Region C, Sub-Region C2), and it is positioned with the A48 road to its north and minor roads to its south, and has the town of Y Bont-faen (Cowbridge) towards the west and the city of Caerdydd (Cardiff) towards the east.

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

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

Extract from the Ordnance Survey Vector Map Local hosted on the Geograph website for Cae Cefn

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 either the main P30 or accompanying Hills to be surveyed sub list as with a 137m summit height adjoined to its triangulation pillar it was deemed lower than Cae Cefn (ST 059 748) which has a 140m summit spot height that appears on the Ordnance Survey 1:25,000 Explorer map, resulting in Cae Cefn being listed as the Dominant hill with 51.43% dominance.  However, as the 140m spot height is to the top of a covered reservoir and as these structures are considered recent man-made constructs the two hills were subsequently surveyed using a Leica GS15 resulting in the following details.

Cae Cefn (ST 05910 74886):  136.2m (natural ground at base of covered reservoir)

Tair Onnen (ST 03660 73979):  137.3m

When LIDAR became available the details for these two hills were re-assessed.  The LIDAR (Light Detection & Ranging) technique produced highly accurate height data that is now freely available for much of England and Wales.  The LIDAR summit details are given below:

Cae Cefn (ST 05915 74885):  136.4m (natural ground at base of covered reservoir)

Tair Onnen (ST 03661 73979):  137.4m

LIDAR image of Cae Cefn (ST 059 748)

The summit height produced by the Leica GS15 survey and by LIDAR analysis gives the summit of Tair Onnen as higher than the natural ground at the immediate base of the covered reservoir on Cae Cefn, and as such this comes within the parameters of the Summit Relocations used within this page heading, these parameters are:

The term Summit Relocations applies to any listed hill whose summit meets the following criteria; where there are a number of potential summit positions within close proximity and the highest point is not where previously given, 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, or when the summit of the hill is in a different field compared to where previously given, or when the natural and intact summit of a hill is confirmed compared to a higher point such as a raised field boundary that is judged to be a relatively recent man-made construct.

Gathering data with the Leica GS15 at the summit of Tair Onnen

Gathering data with the Leica GS15 at the summit of Cae Cefn

Therefore, the summit height produced by the Leica GS15 survey is 137.3m and this is positioned at ST 03660 73979, this position is beside the triangulation pillar atop Tair Onnen and is approximately 2.3km west south-westward from where the originally listed summit of Cae Cefn is positioned.

The full details for the hill are:

Group:  Bro Morgannwg

Name:  Tair Onnen

OS 1:50,000 map:  170

Summit Height:  137.3m (Leica GS15)

Summit Grid Reference (new position):  ST 03660 73979 (Leica GS15)

Bwlch Height:  c 67m (interpolation)

Bwlch Grid Reference:  ST 01235 77663 (interpolation)

Drop:  c 70m

Dominance:  51.20%

Myrddyn Phillips (September 2019)