Mapping Mountains – Significant Name Changes – 30-99m Twmpau and Y Trechol – The Dominant Hills of Wales

Castell (SN 585 789) 

There has been a Significant Name Change to a hill that is listed in the 30-99m Twmpau and Y Trechol – The Dominant Hills of Wales, with the summit height, bwlch height and their locations, the drop and status of the hill derived from LIDAR analysis and a subsequent Trimble GeoXH 6000 survey conducted by Myrddyn Phillips. 

The view from the summit of Castell (SN 585 789)

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

30-99m Twmpau - Welsh hills at or above 30m and below 100m in height with 30m minimum drop, with an accompanying sub list entitled the 30-99m Sub-Twmpau with the criteria for this sub category being all Welsh hills at or above 30m and below 100m 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 30-99m Twmpau by Myrddyn Phillips

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, and which is now available in its entirety on Mapping Mountains in Google Doc format. 

Y Trechol - The Dominant Hills of Wales by Myrddyn Phillips

The hill is adjoined to the Elenydd group of hills which are situated in the central part of the Mid and West Wales Region (Region B, Sub-Region B2), and it is positioned with the coast to its west, the Afon Ystwyth to its east and the A487 road farther to its east, and has the town of Aberystwyth towards the north. 

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

The hill appeared in the original 30-99m Welsh P30 list on Geoff Crowder’s v-g.me website under the name of Y Castell, with an accompanying note stating; Name from ring and bailey at summit.

Y Castell

73m

SN585790

135

213

Name from ring and bailey at summit

 

Since publication of these P30 lists on Geoff Crowder’s v-g.me website there have been a number of Ordnance Survey 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 are current and digitally updated such as the Vector Map Local hosted on the Geograph website and which was entitled the Interactive Coverage Map, and the interactive mapping on the Magic Maps and WalkLakes websites.  Two of the historic maps now available online are the Draft Surveyors map and the Ordnance Survey One-Inch ‘Old Series’ map and it is these maps that form the basis for the compositional change in this hill’s listed name. 

The Draft Surveyor maps consist of the preliminary drawings made by the Ordnance Survey surveyors between the 1780s and 1840 and formed the basis for the first publicly available One-Inch map.  They were drawn at scales of six inches to the mile for areas considered of particular military significance and down to two inches to the mile for other areas.  Fair copies were then produced from these preliminary drawings to one inch to the mile and then copper plates were prepared for printing.  The Draft Surveyors maps for the whole of Wales are now available online and they form an important part in the study of Welsh upland place-names as they bridge the time frame between the late 18^th century and the mid-19^th century when the Ordnance Survey produced their first One-Inch maps, and importantly for this hill and its listed name, it is this map that shows the name as Castell, without the use of the definite article Y. 

Extract from the Ordnance Survey Draft Surveyors map

The One-Inch ‘Old Series’ map was the first map that Ordnance Survey had published and this culminated from the whole of Britain being surveyed between 1791 and 1874 and the detail gathered therein produced at a scale of one inch to the mile and published in sheet format between 1805 and 1874.  The One-Inch ‘Old Series’ maps for the whole of Wales are now available online; they are also available in map format as enlarged and re-projected versions to match the scale and dimensions of the Ordnance Survey 1:50,000 Landranger series and are published by Cassini.  This series of maps form another important part in the study of Welsh upland place-names and bridge the time frame leading up to the production of the Ordnance Survey base map of the Six-Inch series, and importantly for this hill and its listed name, it is also this map that shows the name as Castell, without the use of the definite article Y. 

Extract from the Ordnance Survey One-Inch 'Old Series' map

Therefore, the name this hill is now listed by in the 30-99m Twmpau and Y Trechol – The Dominant Hills of Wales is Castell and the composition and confirmation of its name was derived from the Ordnance Survey Draft Surveyors map and the One-Inch ‘Old Series’ map. 

 

The full details for the hill are: 

Group:  Elenydd 

Name:  Castell

Previously Listed Name:  Y Castell 

OS 1:50,000 map:  135

Summit Height:  77.2m (converted to OSGM15, Trimble GeoXH 6000) 

Summit Grid Reference:  SN 58516 78997 (Trimble GeoXH 6000) 

Bwlch Height:  42.3m (LIDAR) 

Bwlch Grid Reference:  SN 58197 78954 (LIDAR) 

Drop:  34.9m (Trimble GeoXH 6000 summit and LIDAR bwlch) 

Dominance:  45.21% (Trimble GeoXH 6000 summit and LIDAR bwlch) 

 

Myrddyn Phillips (April 2021)

 

 

 

 

 

 

 

  

Mapping Mountains – Significant Height Revisions – 30-99m Twmpau and Y Trechol – The Dominant Hills of Wales

 

Castell (SN 585 789) 

There has been a Significant Height Revision to a hill that is listed in the 30-99m Twmpau and Y Trechol – The Dominant Hills of Wales, with the summit height, bwlch height and their locations, the drop and status of the hill derived from LIDAR analysis and a subsequent Trimble GeoXH 6000 survey conducted by Myrddyn Phillips. 

The view from the summit of Castell (SN 585 789)

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

30-99m Twmpau - Welsh hills at or above 30m and below 100m in height with 30m minimum drop, with an accompanying sub list entitled the 30-99m Sub-Twmpau with the criteria for this sub category being all Welsh hills at or above 30m and below 100m 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 30-99m Twmpau by Myrddyn Phillips

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. 

Y Trechol - The Dominant Hills of Wales by Myrddyn Phillips

The name the hill is listed by is Castell and it is adjoined to the Elenydd group of hills which are situated in the central part of the Mid and West Wales Region (Region B, Sub-Region B2), and it is positioned with the coast to its west, the Afon Ystwyth to its east and the A487 road farther to its east, and has the town of Aberystwyth towards the north. 

When the original 30-99m height band of Welsh P30 hills were published on Geoff Crowder’s v-g.me website this hill was included in the Hills to be surveyed sub list that accompanied the main P30 list, as it was considered not to meet the criteria then used for the main P30 category. 

When 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 an estimated c 29m of drop, based on the 73m summit spot height that appears on the Ordnance Survey 1:25,000 Explorer map and an estimated c 44m bwlch height based on interpolation of 10m contouring between 40m – 50m. 

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

The details for this hill we 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 a 41m spot height appeared on the area of its bwlch and when coupled with the 73m summit spot height these values give this hill 32m of drop. 

However, it was not until LIDAR became available that the details for 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 Castell

The summit height produced by LIDAR analysis is 77.4m, and as the summit has now been surveyed with the Trimble GeoXH 6000 giving 77.2m it is this result that is being prioritised for listing purposes, and this 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 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 77.2m and this was derived from a Trimble GeoXH 6000 survey, this is 4.2m higher than the previous listed summit height of 73m which was based on the spot height that appears on contemporary Ordnance Survey 1:25,000 Explorer maps.

 

ills of Wales, and are reproduced below@

The full details for the hill are:

Group:  Elenydd 

Name:  Castell 

OS 1:50,000 map:  135

Summit Height (New Height):  77.2m (converted to OSGM15, Trimble GeoXH 6000) 

Summit Grid Reference:  SN 58516 78997 (Trimble GeoXH 6000) 

Bwlch Height:  42.3m (LIDAR) 

Bwlch Grid Reference:  SN 58197 78954 (LIDAR) 

Drop:  34.9m (Trimble GeoXH 6000 summit and LIDAR bwlch) 

Dominance:  45.21% (Trimble GeoXH 6000 summit and LIDAR bwlch) 

 

Myrddyn Phillips (April 2021)

 

Mapping Mountains – Hill Reclassifications – 30-99m Twmpau

Castell (SN 585 789) – 30-99m Sub-Twmpau reclassified to 30-99m Twmpau

There has been confirmation of a reclassification to the list of 30-99m Twmpau, with the summit height, bwlch height and their locations, the drop and status of the hill derived from LIDAR analysis and a subsequent Trimble GeoXH 6000 survey conducted by Myrddyn Phillips. 

The view from the summit of Castell (SN 585 789)

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

30-99m Twmpau – Welsh hills at or above 30m and below 100m in height that have 30m minimum drop, with an accompanying sub list entitled the 30-99m Sub-Twmpau with the criteria for this sub category being all Welsh hills at or above 30m and below 100m 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 30-99m Twmpau by Myrddyn Phillips

The name the hill is listed by is Castell and it is adjoined to the Elenydd group of hills which are situated in the central part of the Mid and West Wales Region (Region B, Sub-Region B2), and it is positioned with the coast to its west, the Afon Ystwyth to its east and the A487 road farther to its east, and has the town of Aberystwyth towards the north. 

When the original 30-99m height band of Welsh P30 hills were published on Geoff Crowder’s v-g.me website this hill was included in the Hills to be surveyed sub list that accompanied the main P30 list, as it was considered not to meet the criteria then used for the main P30 category. 

When 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 an estimated c 29m of drop, based on the 73m summit spot height that appears on the Ordnance Survey 1:25,000 Explorer map and an estimated c 44m bwlch height based on interpolation of 10m contouring between 40m – 50m. 

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

The details for this hill we 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 a 41m spot height appears on the area of its bwlch and when coupled with the 73m summit spot height these values give this hill 32m of drop. 

However, it was not until LIDAR became available that the details for 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 Castell (SN 585 789)

LIDAR analysis confirms this hill to have over 30m of drop, and as the summit has now been surveyed with the Trimble GeoXH 6000 it is this result that is being prioritised for listing purposes. 

Therefore, the confirmation of the reclassification of this hill from 30-99m Sub-Twmpau status is due to LIDAR analysis and a subsequent Trimble GeoXH 6000 summit survey, resulting in a 77.2m summit height and a 42.3m bwlch height, with these values giving this hill 34.9m of drop, which is sufficient for it to be classified as a 30-99m Twmpau. 

 

The full details for the hill are: 

Group:  Elenydd 

Name:  Castell 

OS 1:50,000 map:  135

Summit Height:  77.2m (converted to OSGM15, Trimble GeoXH 6000) 

Summit Grid Reference:  SN 58516 78997 (Trimble GeoXH 6000) 

Bwlch Height:  42.3m (LIDAR) 

Bwlch Grid Reference:  SN 58197 78954 (LIDAR) 

Drop:  34.9m (Trimble GeoXH 6000 summit and LIDAR bwlch) 

 

Myrddyn Phillips (April 2021)

 

 

 

 

  

Mapping Mountains – Trimble Surveys – Elenydd

 

15.10.20  Castell (SN 585 789) 

The summit area of Castell with Pendinas in the background

One of the beauties of hill bagging is the element of exploration as a list of hills will take you on an adventure to places otherwise not visited.  Many of these sink to the recesses of memory where one hill merges in to another, whilst some linger in memories eye.  I am sure Castell will be a part of the latter, as today it shone in early morning autumnal light, looking out toward the coast that sprinkled azure like to the distant horizon. 

Today consisted of hill bagging in the ever welcome company of Charles Everett.  We met in Llangurig and I then drove west with Charles navigating on a myriad of narrow country lanes to our pre-planned parking spots for mini-expeditions to nine hills that took a very leisurely, all day to visit. 

Our first hill was Castell, which prior to our visit I had analysed via LIDAR, as I had for all our subsequent hills, with only one summit of the nine not as of yet having LIDAR coverage.  LIDAR is proving a great help when out surveying, and its accuracy in position is an extremely welcome aid and addition.  

LIDAR image of Castell (SN 585 789)

Driving west toward Aberystwyth, Charles then navigated us over the Afon Ystwyth to a narrow lane leading east and then north of the hill.  Google Earth had helped pinpoint suitable parking places and we were soon walking back up the lane to where open hillside rose steeply above.  Approaching the hill from this direction avoided the wood that fringes the lower part of this hill. 

Dew laden and shaded grass swept upward toward the summit of Castell with ever widening views behind us toward the north, where the sea glistened and the monument to the Duke of Wellington on the summit of Pendinas (SN 584 802) was ever present.  I’d surveyed Pendinas in October 2018 and it proved a fine viewpoint. 

Pendinas from the ascent of Castell

The upper part of Castell as its name implies is crowned by an ancient hillfort.  This is steep sided and as Charles headed up I lingered to admire the view.  As I crested the grassed rampart Charles was busy clearing a section of the summit of gorse, which I appreciated. 

Gathering data at the summit of Castell

When I joined Charles near the summit a small herd of cows sauntered through a gap in the earthen ramparts to join us on the inner part of the ancient hill fort.  They seemed interested in what we were doing, but as the Trimble gathered its allotted data, they thankfully kept a safe distance from the equipment, no doubt partly discouraged by the copious amount of gorse. 

Heading on to the ramparts to see what the Trimble is doing

To our south morning mist lingered in the valley, highlighted by the low sun, it was so wonderful to be here quietly surveying the hill in Charles’ company as the cows grazed their way across the summit area. 

Mist laden valley

Once the Trimble was packed away we headed toward a gate and then veered right down the steep field and back to the narrow lane.  Arriving at the car the walk and survey had taken just over 45 minutes and was a fine start to the day’s proceedings.  The next hill on our route is listed as Bryn Bras (SN 573 772) and was no more than 2km to our south-west. 

 

Survey Result: 

 

Castell (significant name change)  

Summit Height:  77.2m (converted to OSGM15, Trimble GeoXH 6000) (significant height revision)

Summit Grid Reference:  SN 58516 78997 (Trimble GeoXH 6000)

Bwlch Height:  42.3m (LIDAR)

Bwlch Grid Reference:  SN 58197 78954 (LIDAR)

Drop:  34.9m (Trimble GeoXH 6000 summit and LIDAR bwlch) (30-99m Sub-Twmpau reclassified to 30-99m Twmpau)

Dominance:  45.21% (Trimble GeoXH 6000 summit and LIDAR bwlch)

 

 

For further details please consult the Trimble Survey Spreadsheet