Showing posts with label Pen Twmp. Show all posts
Showing posts with label Pen Twmp. Show all posts

Sunday, 19 August 2018

Mapping Mountains – Significant Name Changes – 200m Twmpau and Y Trechol – The Dominant Hills of Wales


Pen Twmp (SM 988 329)

There has been a Significant Name Change to a hill that is listed in the 200m Twmpau and Y Trechol – The Dominant Hills of Wales, with the bwlch height and its Dominant status confirmed via LIDAR analysis conducted by Myrddyn Phillips.

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

200m Twmpau – All Welsh hills at or above 200m and below 300m in height that have 30m minimum drop, with the word Twmpau being an acronym standing for thirty welsh metre prominences and upward. 

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 addition Welsh P30 hills whose prominence is 33% or more and below 50% 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 3rd December 2015.

The hill is adjoined to the Mynydd Preseli group of hills, which are situated in the south-western part of Mid and West Wales (Region B, Sub-Region B4), and it is positioned with the A 40 road to its west and the B 4313 road to its north and has the Nant y Bugail to its south-west and the River Aer to its north-north-east, and has the town of Abergwaun (Fishguard) towards the north-west.

The hill originally appeared in the 200m P30 list on Geoff Crowder’s v-g.me website under the invented name of Bryn Pentre-newydd with an accompanying note stating; Name from buildings to the North-East. 


Bryn Pentre-newydd
217m
157
35
Name from buildings to the North-East.


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.  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.

During the initial compilation of the Dominant list I made a number of place-name enquiries for qualifying hills, including this one.  I was put in contact with Elin Evans and Julian Fry, at the time of our conversation Elin was a school teacher and Julian a web master for a site concentrating on Llanychaer, this being the small community where they lived.  Elin’s grandfather grew up at Penlan (SM 997 333), and her parents; John and Rhian Evans lived in the bungalow adjoined to the farm of Cronllwyn (SM 986 348), therefore her family have lived beside this hill for at least three generations.

On the day I phoned, Elin’s parents were upset as one of their sheep dogs had been put down, therefore Julian offered to speak with John and Rhian at an opportune moment, and he later did so and phoned me with details relating to this hill and its name.  The name given Julian for this hill by Elin’s parents; John and Rhian Evans is Pen Twmp.

Therefore, the name this hill is now listed by in the 200m Twmpau and Y Trechol – The Dominant Hills of Wales is Pen Twmp, and this name was derived from local enquiry.


The full details for the hill are:

Group:  Mynydd Preseli

Name:  Pen Twmp

Previously Listed Name:  Bryn Pentre-newydd
 
Summit Height:  217m

OS 1:50,000 map:  157

Summit Grid Reference:  SM 98820 32984 
 
Drop:  109m

Dominance:  50.09%


Myrddyn Phillips (August 2018)




Tuesday, 14 August 2018

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


Pen Twmp (SM 988 329) – Lesser Dominant reclassified to Dominant

There has been a reclassification to the listing of Y Trechol – The Dominant Hills of Wales due to LIDAR analysis conducted by Myrddyn Phillips, with the criteria for this list being:

Y Trechol – The Dominant Hills of Wales - Welsh P30 hills whose prominence equal or exceed half that of their absolute height.  With an accompanying sub list entitled Y Trechol - The Lesser Dominant Hills of Wales, with the criteria for this sub category being those additional Welsh P30 hills whose prominence is 33% or more and below 50% of their absolute height.

This hill was initially listed as a Dominant hill based on interpolation of bwlch contours and later reclassified to Lesser Dominant status based on the 109m spot height that appears on the area of this hill’s bwlch on the Ordnance Survey Interactive Coverage Map hosted on the Geograph website.

Extract from the Ordnance Survey Interactive Coverage Map hosted on the Geograph website

A locally known name of the hill is Pen Twmp and it is adjoined to the Mynydd Preseli group of hills, which are situated in the south-western part of Mid and West Wales (Region B, Sub-Region B4).  The hill is positioned with the A 40 road to its west and the B 4313 road to its north and has the Nant y Bugail to its south-west and the River Aer to its north-north-east, and has the town of Abergwaun (Fishguard) towards the north-west.

If wanting to visit the hill permission to do so should be sought as it is not a part of designated open access land, for those wishing to do so a public footpath passes to the west of the summit and can be accessed from either the north or south-west.

The reclassification of Pen Twmp to Dominant status is due to LIDAR bwlch analysis conducted by Myrddyn Phillips.  The LIDAR (Light Detection & Ranging) technique produced highly accurate height data that is now freely available for much of England and Wales.


The 2m DTM LIDAR analysis gives the hill the following details:

Name:  Pen Twmp

Summit Height:  217m

Summit Grid Reference:  SM 98820 32984

Bwlch Height:  108.3m

Bwlch Grid Reference:  SM 99284 32968

Drop:  109m

Dominance:  50.09%


LIDAR image of Pen Twmp

LIDAR image of the bwlch of Pen Twmp

Therefore, the 217m summit spot height and the 108.3m LIDAR analysis for the bwlch position at SM 99284 32968 gives this hill 109m of drop and 50.09% Dominance, which is sufficient for it to be reclassified to a Dominant hill.


The full details for the hill are:

Group:  Mynydd Preseli

Name:  Pen Twmp

Dominance:  50.09%

OS 1:50,000 map:  157

Summit Grid Reference:  SM 98820 32984

Summit Height:  217m

Drop Summit to Bwlch:  109m

Drop Bwlch to ODN:  108.3m


Myrddyn Phillips (August 2018)





Thursday, 9 August 2018

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


Pen Twmp (SM 988 329) – Dominant reclassified to Lesser Dominant

THIS HILL HAS SUBSEQUENTLY BEEN RECLASSIFIED BACK TO DOMINANT STATUS

There has been a reclassification to the listing of Y Trechol – The Dominant Hills of Wales due to data on the Ordnance Survey Interactive Coverage Map hosted on the Geograph website.  This reclassification is retrospective as it was initiated when data on this mapping was first analysed.

The criteria for this list are:

Y Trechol – The Dominant Hills of Wales - Welsh P30 hills whose prominence equal or exceed half that of their absolute height.  With an accompanying sub list entitled Y Trechol - The Lesser Dominant Hills of Wales, with the criteria for this sub category being those additional Welsh P30 hills whose prominence is 33% or more and below 50% of their absolute height.

During 2006 and 2007 drop values were added to the Welsh P30 lists that had been published on Geoff Crowder’s v-g.me website, this hill was then listed with an estimated c 110m of drop based on the 217m summit spot height that appears on the Ordnance Survey 1:25,000 Explorer map and an estimated bwlch height of c 107m based on interpolation of bwlch contouring between 105m – 110m, with these values giving this hill 50.69% Dominance, and it was listed as such when this section of the Dominant list was completed in late January / early February 2012.

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

A locally known name of the hill is Pen Twmp and it is adjoined to the Mynydd Preseli group of hills, which are situated in the south-western part of Mid and West Wales (Region B, Sub-Region B4).  The hill is positioned with the A 40 road to its west and the B 4313 road to its north and has the Nant y Bugail to its south-west and the River Aer to its north-north-east, and has the town of Abergwaun (Fishguard) towards the north-west.

If wanting to visit the hill permission to do so should be sought as it is not a part of designated open access land, for those wishing to do so a public footpath passes to the west of the summit and can be accessed from either the north or south-west.

Shortly after Pen Twmp was first listed as a Dominant hill I was informed on how to access what is now known as the Ordnance Survey Interactive Coverage Map that is hosted on the Geograph website.  The larger scale interactive map on this website gives many spot heights that are not shown on other publicly available mapping, and when the details for this hill were analysed this map shows a 109m spot height on the area of this hill’s bwlch, and when coupled with the 217m summit spot height, these values gave the hill 108m of drop and 49.77% Dominance and it was therefore reclassified from a Dominant to a Lesser Dominant hill.

Extract from the Ordnance Survey Interactive Coverage Map hosted on the Geograph website


The full details for the hill are:

Group:  Mynydd Preseli

Name:  Pen Twmp

Dominance:  49.77%

OS 1:50,000 map:  157

Summit Grid Reference:  SM 988 329

Summit Height:  217m

Drop Summit to Bwlch:  108m

Drop Bwlch to ODN:  109m


Myrddyn Phillips (August 2018)