Wednesday, 28 June 2017

Mapping Mountains – Hill Reclassifications – 30-99m Twmpau


30-99m Twmpau – Hill Reclassifications

The 30-99m Twmpau (thirty welsh metre prominences and upward) are the Welsh hills at or above 30m and below 100m in height that have a minimum drop of 30m.  Accompanying the main P30 list is a sub list entitled the 30-99m Sub-Twmpau with the qualification to 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.

The list is authored by Myrddyn Phillips and the posts that have appeared on Mapping Mountains detailing the additions, reclassifications and deletions to the main P30 list and the sub list appear below presented chronologically in receding order.









Mapping Mountains - Hill Reclassifications - 30-99m Twmpau

Pt. 23.8m (SM 706 236) - Double Sub-Twmpau addition (9th reclassification)

Survey post for Pt. 23.8m


There has been a confirmation of an addition to the listing of Twmpau (thirty welsh metre prominences and upward) hills due to a recent survey with the Trimble GeoXH 6000.  The hill is now listed in the Double Sub-Twmpau list adjoined to the 30–99m height band of Twmpau hills and is situated on the eastern part of Ynys Dewi, which is also commonly known as Ramsey, this is an island to the west of St David’s in south-west Wales.

The hill did not appear in the Sub-List which accompanied the original Welsh P30 listings on Geoff Crowder’s v-g.me website as the Sub-List only included hills whose map details showed that when surveyed they may stand a chance of qualification to the main P30 list, with the title of the Sub-List being ‘Hills to be surveyed.’  And as this hill only has an uppermost 20m ring contour it was judged that even when surveyed there was no chance of it reaching the dizzying heights of having a minimum of 30m of drop, and therefore it was not included in the Sub-List.  However, since first publication this Sub-List has been standardised and now includes all hills that have a minimum of 20m of drop and below 30m of drop.

The Trimble GeoXH 6000 survey that resulted in this hill’s confirmation as a Double Sub-Twmpau was conducted during the afternoon of 15th May 2016 in beautiful, sunny and still conditions.

As the hill is situated on an island the only way to approach is via boat and the only company with permission to land on Ynys Dewi is Thousand Island Adventures (tel: 01437-721721).  The hill can be easily accessed as it rises immediately above where the boat docks, however when I visited it I sought permission to do so as it is off the beaten track as far as visitors are concerned.

The hill does not possess either a map or local name and therefore the point (Pt. 23.8m) notation is being used.  It currently has an uppermost 20m ring contour encircling its summit on Ordnance Survey maps and is now joined to the remainder of Ynys Dewi by the walkway leading to the track above where the boat docks.  This walkway is elevated above the sea and is man-made, with the natural connection between this small hill and the bulk of the island being a small pebbled bit of land below the track, it is estimated that this natural land is c 2m high.

Therefore the survey with the Trimble GeoXH 6000 resulted in a 23.8m (converted to OSGM15) summit height and with an estimated bwlch height of c 2m, this hill has c 22m of drop and therefore qualifies as a Double Sub-Twmpau.


The full details for the hill are:

Cardinal Island:  Ynys Dewi

Summit Height:  23.8m (converted to OSGM15)

Name:  Pt. 23.8m

OS 1:50,000 map:  157

Summit Grid Reference:  SM 70677 23686

Drop:  c 22m



Pt. 23.8m (SM 706 236) now confirmed as a Double Sub-Twmpau


Myrddyn Phillips (May 2016)







Mapping Mountains - Hill Reclassifications - 30-99m Twmpau

Foel Fawr (SM 705 225) - 30-99m Sub-Twmpau reclassified to 30-99m Twmpau (8th reclassification)

Survey post for Foel Fawr


There has been a reclassification to the listing of Twmpau (thirty welsh metre prominences and upward) hills due to a recent survey with the Trimble GeoXH 6000.  The hill is listed in the 30m–99m height band of Twmpau hills and is situated on the southern part of Ynys Dewi (Ramsey), which is an island to the west of St David’s in south-west Wales.

The hill appeared in the original Welsh P30 listings on Geoff Crowder’s v-g.me website and was included in the Sub-List adjoined to the 30m-99m height band of hills, and was the only hill listed in this Sub-List under the grouping of the Pembrokeshire Islands.

The Trimble GeoXH 6000 survey that resulted in this hill’s reclassification was conducted on the 15th May 2016 in the mid-afternoon in beautiful, sunny and still conditions.

As the hill is situated on an island the only way to approach is via boat and the only company with permission to land on Ynys Dewi is Thousand Island Adventures (tel: 01437-721721).  The hill can be easily accessed from where the boat docks as a gravelled track leads up to The Farmhouse from where a good path heads toward the southern part of the island.

The name of the hill is Foel Fawr and it is given a 72m summit spot height on current Ordnance Survey maps, and has been listed with an estimated bwlch height of c 43m based on bwlch contouring between 40m – 45m, these values gave the hill c 29m of drop and therefore it remained listed as a Sub-Twmpau.

Two points were surveyed for summit position and also for bwlch position, these are given below:


Summit 1:  72.0m (71.954m, converted to OSGM15)) at SM 70542 22567

Summit 2:  71.8m (71.821m, converted to OSGM15) at SM 70539 22566

Bwlch 1:  41.8m (41.764m, converted to OSGM15)) at SM 70504 22667

Bwlch 2:  41.9m (41.899m, converted to OSGM15) at SM 70511 22665


The surveys for bwlch position were conducted on the valley to valley traverse and therefore the higher result is taken when calculating the drop value for the hill. 

Therefore the survey with the Trimble GeoXH 6000 resulted in a 72.0m (converted to OSGM15) summit height and a 41.9m (converted to OSGM15) bwlch height, with these values giving the hill 30.1m of drop.  As the minimum drop for qualification to the main Twmpau list is 30m this means that Foel Fawr is reclassified from a Sub-Twmpau to a Twmpau.


The full details for the hill are:

Cardinal Island:  Ynys Dewi

Summit Height:  72.0m (converted to OSGM15)

Name:  Foel Fawr

OS 1:50,000 map:  157

Summit Grid Reference:  SM 70542 22567

Drop:  30.1m (converted to OSGM15)


Foel Fawr (SM 705 225) now reclassified from a Sub-Twmpau to a Twmpau


Myrddyn Phillips (May 2016)







Mapping Mountains - Hill Reclassifications - 30-99m Twmpau

Ynys Fach (SM 822 327) - 30-99m Twmpau reclassified to 30-99m Sub-Twmpau (7th reclassification)

Survey post for Ynys Fach


There has been a reclassification to the listing of the Twmpau (thirty welsh metre prominences and upward) hills due to a recent survey with the Trimble GeoXH 6000.  The hill is listed in the 30m – 99m height band of Twmpau hills and is situated on the northern Pembrokeshire coast close to the small communities of Porthgain to its west and Trefin (Trevine) to its east.

The hill is better described as an island, and even more so as a tidal island, and is connected to the mainland of Wales by a pebbled beach that according to maps is cut off from the mainland at high water.  It can be approached by boat, but an ascent of the island is feasible, albeit steep and potentially dangerous, from the mainland.  This approach starts from directly opposite the island and necessitates finding a route down bi-passing the rock and cliffs that predominate this part of the coastline.  If attempting this route please be careful.

The island was surveyed on 14th May 2016 on a beautiful sunny evening in the company of Adrian Rayner, Ayako and Rob Woodall.  It was Rob’s suggestion to go and have a look at it, and he found the route down to the pebbled beach which constitutes this island’s connecting bwlch.

The name of the island is Ynys Fach and it first appeared in a hill list on Geoff Crowder’s v-g.me website as a part of the original listing of Welsh P30s taking in the 100m height bands below the height of 500m. 

Ynys Fach is given an uppermost contour ring of 30m on current Ordnance Survey maps with no adjoined spot height.  However, the Ordnance Survey Six Inch map revised in 1906 and published in 1908 gives a 99ft height for the island, this is when the composition of the name was presented as Ynys Fâch, as opposed to the current Ynys-fach.  The 99ft spot height was later given on the Ordnance Survey 1:25,000 Historical map, with 99ft being an approximate 30.2m in metric measurement.

Two points were surveyed for summit position and these are given below:


Summit 1:  30.8m (30.789m, converted to OSGM15) at SM 82209 32743

Summit 2:  30.7m (30.727m, converted to OSGM15) at SM 82217 32752


The data set for the bwlch was remarkably good when considering that the equipment was placed in what resembled an enclosed and walled canyon, with the result being 1.2m (1.225m, converted to OSGM15) at SM 82180 32693.  These values give Ynys Fach a drop of only 29.6m and therefore it is reclassified from a 30-99m Twmpau to a Sub-Twmpau.


The full details for the hill are:

Cardinal Hill:  Garn Fawr

Summit Height:  30.8m (converted to OSGM15)

Name:  Ynys Fach

OS 1:50,000 map:  157

Summit Grid Reference:  SM 822 327

Drop:  29.6m (converted to OSGM15)



Ynys Fach (SM 822 327) now reclassified from a Twmpau to a Sub-Twmpau



Myrddyn Phillips (May 2016)







Mapping Mountains - Hill Reclassifications - 30-99m Twmpau

Daufraich (SM 661 236) - Double Sub-Twmpau addition (6th reclassification)

Survey post for Daufraich


There has been an addition to the Sub category within the 30–99m Twmpau (thirty welsh metre prominences and upward) hill list instigated by a survey with the Trimble GeoXH 6000.   The hill is better described as an island and is situated to the west of St David’s in south-west Wales, and forms part of the chain of islands known as the Bishops and Clerks.

The Trimble GeoXH 6000 survey that resulted in this hill’s inclusion as a 30–99m Sub-Twmpau was conducted on the 14th May 2016 in the early afternoon on a fine day in good, dry and sunny conditions.  The trip to this and other islands was organised by Adrian Rayner and the survey took place in the company of Adrian, Rob Woodall, Bob Kerr and Jon Glew, with Sheila Glew, Akako and Sarah Kerr remaining on the RIB whilst we were on the island.

Not surprisingly the island can only be accessed by boat, and although landing is relatively easy the way to the summit involves a scramble, and although not difficult it is exposed, with the prospect of an undignified dunking in the sea a distinct probability if one foot hold proves a wee bit slippy.

The name of the island is Daufraich and it comprises two parts, with its easterly high point being given the map height of 20m, and its westerly high point being given two positions of 21m high on current Ordnance Survey maps.  We only had time to land on the westerly part of the island which proved visually higher than the easterly part.  I also only had time for one survey, and consensus of opinion was that the highest part of the island was where the south-eastern 21m spot height appears on the ground, with the ground where the north-western 21m spot height is positioned being assessed as slightly lower.

Daufraich was not included in the Sub-List which accompanied the original listing of 30m -99m hills that appeared on Geoff Crowders v-g.me website, as that Sub-List comprised ‘Hills to Survey’ and as this island was under 30m in height it was not included as the only hills that were, were those deemed to have chance of qualifying for the main P30 list after having been surveyed.  However, this Sub-List has now been standardised and includes all hills that are known to have at least 20m of drop and below 30m of drop.

The survey with the Trimble GeoXH 6000 resulted in a 21.7m (converted to OSGM15) summit height, which as an island is also this hill’s drop value, and therefore confirming its entry in to the 30–99m Sub-Twmpau ranks.


The full details for the hill are:

Cardinal Island:  Bishops and Clerks

Summit Height:  21.7m (converted to OSGM15)

Name:  Daufraich

OS 1:50,000 map:  157

Summit Grid Reference:  SM 66199 23673

Drop:  21.7m (converted to OSGM15)



Daufraich (SM 661 236) the new Double Sub-Twmpau



Myrddyn Phillips (May 2016)







Mapping Mountains - Hill Reclassifications - 30-99m Twmpau

Moel y Gadair (SH 521 391) 30-99m Twmpau reclassified to 30-99m Sub-Twmpau (5th reclassification)

Summit survey post for Moel y Gadair

Bwlch survey post for Moel y Gadair


There has been a reclassification to the listing of Twmpau (thirty welsh metre prominences and upward) hills due to a recent survey with the Trimble GeoXH 6000.  The hill is listed in the 30–99m height band of Twmpau hills and is situated to the south-west of the small community of Pentrefelin, which is situated between Porthmadog to the east and Cricieth to the south-west.

The hill has been reclassified from a P30 Twmpau to a Sub-Twmpau, and re-joins these ranks after being originally listed in the ‘Hills to Survey’ Sub-List that appeared on Geoff Crowder’s v-g.me website.  On subsequent reassessment the hill was promoted to full P30 status due to bwlch contour interpolation, with a drop value of c 30m based on a summit spot height of 67m and an estimated bwlch height of c 37m.

The hill is named Moel y Gadair and its summit was surveyed with the Trimble GeoXH 6000 on the 15th June 2015 giving a height of 66.7m (converted to OSGM15).  On that day I misinterpreted the bwlch contouring and therefore took a number of data sets from the incorrect place.  Having re-examined Ordnance Survey mapping and driven a Google Car on the A 497 which passes over this bwlch I was confident that I now knew where the critical bwlch was positioned.

The subsequent survey of this hill’s bwlch resulted in a height value of 38.1m (converted to OSGM15), giving the hill insufficient drop to retain its P30 Twmpau status.


The full details for the hill are:

Cardinal Hill:  Moel Hebog

Summit Height:  66.7m (converted to OSGM15)

Name:  Moel y Gadair

OS 1:50,000 map:  124

Summit Grid Reference:  SH 521 391

Drop:  28.5m (converted to OSGM15)


Moel y Gadair (SH 521 391) now reclassified from a P30 Twmpau to a Sub-Twmpau with 28.5m of drop

For details on the survey that reclassified this hill from P30 Twmpau to Sub-Twmpau status please click {here} for summit and {here} for the bwlch survey.


Myrddyn Phillips (February 2016)






Mapping Mountains - Hill Reclassifications - 30-99m Twmpau

Castell Cricieth (SH 500 377) - 30-99m Twmpau addition (4th reclassification)

Survey post for Castell Cricieth
  

There has been an addition to the listing of Twmpau (thirty welsh metre prominences and upward) hills due in part to a recent survey with the Trimble GeoXH 6000.  The hill is listed in the 30m-99m height band of Twmpau hills and is situated in the town of Cricieth.

Its P30 status was first discovered by Alex Cameron who rightly judged that with a 48m summit spot height which appears on the Ordnance Survey enlarged mapping hosted on the Geograph website, and with bwlch contouring between c 15m – c 20m, with an estimated bwlch height of c 18m, this hill should be listed as a P30 with c 30m of drop.

The hill is Castell Cricieth which as its name implies has a castle on top of it.

This hill is one of the rarities that have not appeared in previous Sub-Lists before its entrance as a fully-fledged P30.


The full details for the hill are:

Cardinal Hill:  Moel Hebog

Summit Height:  49.6m (converted to OSGM15)

Name:  Castell Cricieth

OS 1:50,000 map:  123

Summit Grid Reference:  SH 500 377

Drop:  30.3m (converted to OSGM15)


Castell Cricieth (SH 500 377) P30 status now confirmed by the Trimble GeoXH 6000

For details on the survey that confirmed this hill's status as a 30-99m Twmpau please click {here}


Myrddyn Phillips (June 2015)






Mapping Mountains - Hill Reclassifications - 30-99m Twmpau

Carreg yr Eryr (SH 526 378) - 30-99m Sub-Twmpau reclassified to 30-99m Twmpau (3rd reclassification)

Survey post for Carreg yr Eryr


There has been a new addition to the listing of Twmpau (thirty welsh metre prominences and upward) hills due to a recent survey with the Trimble GeoXH 6000.  The hill is listed in the 30m-99m height band of Twmpau hills and is situated on the outskirts of Morfa Bychan overlooking Black Rock Sands to its east and Castell Cricieth to its west.

The first time Carreg yr Eryr ever appeared in a hill list was in 2003 when the original Welsh P30 hills under 500m in height were published on Geoff Crowder’s v-g.me website.  It was then listed in the Sub-List which was named ‘Hills to Survey’.  The reason for this was that Carreg yr Eryr was not given a summit and bwlch spot height that gave it a minimum of 30m of drop on the then current Ordnance Survey map, because of this it was listed as a Sub.  When this list was first published on Geoff’s website it did not include a drop value for each hill, although the qualification for the main list and the Sub-List was based on drop.  These drop values were added at a later date.

When these drop values were added to the list I also decided to include hills in the Main P30 Twmpau list through interpolation of map contours, although some of these details were passed onto Geoff, the great majority were not.  When drop figures were added to the list I gave Carreg yr Eryr c 30m of drop and promoted it into the ranks of P30 hills.  This drop value was estimated from its 53m summit spot height and an estimated bwlch height of c 23m based on the 1:25,000 map bwlch contouring between c 20m – c 30m.  Since this hill was promoted into the P30 ranks the Ordnance Survey enlarged map on the Geograph website has been made available, and this map has contour intervals of 5m and gives the bwlch contouring between c 20m and c 25m, with an estimated bwlch height of c 23m, so the hill remained listed as a P30.  Even though the hill had been promoted in my list the details were never made public, so it was now time to have it Trimbled and to confirm its status via the Mapping Mountains blog.


The full details for the hill are:

Cardinal Hill:  Moel Hebog

Summit Height:  53.3m (converted to OSGM15)

Name:  Carreg yr Eryr

OS 1:50,000 map:  124

Summit Grid Reference:  SH 526 378

Drop:  30.9m (converted to OSGM15)


Carreg yr Eryr (SH 526 378) P30 status now confirmed by the Trimble GeoXH 6000

For details on the survey that confirmed this hill's 30m-99m Twmpau status please click {here}

Myrddyn Phillips (June 2015)






Mapping Mountains - Hill Reclassifications - 30-99m Twmpau

Ynys Tywyn (SH 571 385) - 30-99m Sub-Twmpau addition (2nd reclassification)

Survey post for Ynys Tywyn
   

There has been an addition to the 30-99m Twmpau list with this hill entering the sub category of 30–99m Sub-Twmpau.  The name of the hill is Ynys Tywyn (SH 571 385) and it is situated at the end of the Cob in Porthmadog in north-west Wales.  

Ynys Tywyn has a small uppermost 20m contour ring on Ordnance Survey maps, but no spot height, and a recent survey with the Trimble GeoXH 6000 confirms that the hill is over 20m but under 30m in height and as it is the high point of an island that is now connected to Porthmadog by the Cob, and therefore its height is also considered to be its drop, it has been included in the 30-99m Sub-Twmpau category.  The summit is crowned by a large flat rock and gorse bushes and has fine views over the Afon Glaslyn to the higher mountains of Eryri.


The full details for the hill are:

Cardinal Hill:  Moel Hebog

Summit Height:  21.8m (converted to OSGM15)

Name:  Ynys Tywyn

OS 1:50,000 map:  124

Summit Grid Reference:  SH 571 385

Drop:  21.8m (converted to OSGM15)


Ynys Tywyn (SH 571 385) is now confirmed as a 30-99m SubTwmpau

For details on the survey that promoted this hill to 30–99m Sub-Twmpau status please click {here}


Myrddyn Phillips (January 2015)







Mapping Mountains - Hill Reclassifications - 30-99m Twmpau

Ynys Glog (SH 596 398) and Ynys Berfedd (SH 599 398) - 30-99m Twmpau additions (1st reclassification) 

Survey post for Ynys Glog

Survey post for Ynys Berfedd


There have been three new Welsh island P30 hills recently discovered.  These additions to the 30-99m Twmpau list were found by Aled Williams through map study and local knowledge of the area, with two of these hills accepted automatically to the listing of Twmpau hills and with the other hill entering the Twmpau list through surveying with the Trimble GeoXH 6000.

The two hills automatically accepted in to the 30-99m Twmpau list are Ynys Glog (SH 596 398) and Ynys Berfedd (SH 599 398).  Whilst the other hill is named Ynys Hir (SH 566 396) which was confirmed as a P30 through surveying with the Trimble GeoXH 6000.  

Aled considered the hill at SH 566 396 and its adjacent hill at SH 566 398 which is also known as Ynys Hir as suitable candidates for surveying with a high chance of promotion to the P30 ranks, and considered that the uppermost 20m ring contour given to both hills on the Ordnance Survey enlarged mapping hosted on the Geograph website was incorrect and a misrepresentation of their actual height.


A note from Aled:

Two New P30 Hills

Analysis of OS enlarged mapping on the Geograph website confirms two P30 hills that are absent from both the '30-99m Twmpau' list by Myrddyn Phillips (2004) and the 'Tumps' list by Mark Jackson (2009). I bring this information to the attention of the authors.


Name: Ynys Glog
Height: 40.6m (converted to OSGM15)
Drop: 32.7m (converted to OSGM15)
Grid Reference: SH 59647 39826



Name: Ynys Berfedd
Height: 42.9m (converted to OSGM15)
Drop: 36.1m (converted to OSGM15)
Grid Reference: SH 59943 39865



Aled Williams (03/02/2014).




The discovery of new P30’s is not a rarity, but what is unusual is that each of these hills was once an island that is now landlocked in the area known as Traeth Mawr, this is near to Aled’s home in Porthmadog.  Subsequently all of these hills have been surveyed using the Trimble GeoXH 6000 and their respective results are given above.



For more detail of the Trimble survey that promoted Ynys Hir to 30-99m Twmpau status click {here} 



A post by Aled on the land known as Traeth Mawr and its many small islands is due for publication in the Guest Contributor page on the Mapping Mountains blog in March. 


Aled Williams at the summit of Ynys Hir (SH 566 396)

Myrddyn Phillips (February 2014)