Thursday, 14 November 2019

Mapping Mountains – Significant Name Changes – Y Pedwarau – The 400m Hills of Wales


Garreg y Noddfa (SN 930 761)

There has been a Significant Name Change to a hill that is listed in the Y Pedwarau – The 400m Hills of Wales, with the summit height and its location determined by a Leica 530 survey conducted by John Barnard, Graham Jackson and Myrddyn Phillips on the 26th February 2009, and the bwlch height and its location, the drop and status of the hill confirmed by LIDAR analysis conducted by Aled Williams.

The Trimble GeoXH 6000 gathering data at the summit of Garreg y Noddfa

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

Y PedwarauThe 400m Hills of Wales.  Welsh hills at or above 400m and below 500m in height that have 30m minimum drop; with the list being co-authored by Myrddyn Phillips and Aled Williams and published on Mapping Mountains in Google Doc format.

The hill is adjoined to the Hirddywel group of hills, which are situated in the north-eastern part of Mid and West Wales (Region B, Sub-Region B1), and it is positioned with the A470 road and the Afon Gwy (River Wye) to its west and the B4518 road to its east, and has the town of Llanidloes towards the north and the town of Rhaeadr Gwy (Rhayader) towards the south-east.

The hill appeared in the original Welsh 400m P30 list on Geoff Crowder’s v-g.me website under the name of Bryn Titli, which is a name that appears close to the summit of this hill on contemporary Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer maps. 

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

The listed name of this hill was revised to Fawnog Gnapiog in the 1st edition of the Y Pedwarau published by Europeaklist in May 2013.  With this revised name being one of the main named features of the hill as opposed to that of Bryn Titli which has been placed consistently by Ordnance Survey adjacent to a 492.7m high hill positioned at SN 93383 75719.  

Extract from the Ordnance Survey series of Six-Inch maps

Since publication of the 1st edition of Y Pedwarau the Tithe maps for Wales have become available online.  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 on Tithe maps is given a number that 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.  However, in this instance it is the actual Tithe map that gives the name of Garreg y Noddfa beside the summit of this hill.  With the details on the Tithe map appearing in the parish of Llangirrig [sic] and in the county named as Montgomery.

Therefore, the name this hill is now listed by in the Y Pedwarau – The 400m Hills of Wales is Garreg y Noddfa, and this was derived from the Tithe map.


The full details for the hill are:

Group:  Hirddywel

Name:  Garreg y Noddfa

Previously Listed Name:  Fawnog Gnapiog

OS 1:50,000 map:  136, 147

Summit Height:  495.7m (Leica 530, converted to OSGM15)

Summit Grid Reference:  SN 93041 76174 (Leica 530)

Bwlch Height:  436.7m (LIDAR)

Bwlch Grid Reference:  SN 93730 74216 (LIDAR)

Drop:  59.0m (LIDAR)



Myrddyn Phillips and Aled Williams (November 2019)







Wednesday, 13 November 2019

Mapping Mountains – Significant Height Revisions – Y Trichant – The 300m Hills of Wales


Dinas (SH 699 738)

There has been a Significant Height Revision to a hill that is now listed in the Y Trichant – The 300m Hills of Wales, with the summit height, bwlch height and their locations, the drop and status of the hill confirmed by LIDAR analysis conducted by Myrddyn Phillips.

LIDAR summit image of Dinas (SH 699 738)

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

Y Trichant – The 300m Hills of Wales – Welsh hills at or above 300m and below 400m in height that have 30m minimum drop, with an accompanying sub list entitled the Sub-Trichant with the criteria for this sub category being all Welsh hills at or above 300m and below 400m in height with 20m or more and below 30m of drop.  The list is authored by Myrddyn Phillips, with the Introduction to the list and the renaming of it appearing on Mapping Mountains on the 13th May 2017.

The name the hill is listed by is Dinas and it is adjoined to the Carneddau 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 A55 road to its north-west, and has the town of Penmaen-mawr towards the north-east and the town of Llanfairfechan towards the north-west. 

When the original 300m height band of Welsh P30 hills were published on Geoff Crowder’s v-g.me website this hill was not included in the Hills to be surveyed sub list that accompanied the main P30 list, as it did not meet the criteria then used for this sub category. 

After the sub list was standardised, and interpolated heights and drop values also included the details for this hill were re-evaluated, but as the contemporary Ordnance Survey 1:25,000 Explorer map did not have a summit spot height and only an uppermost 320m continuous contour and bwlch contouring between 300m – 310m, an accurate interpolated drop value was hard to determine.

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

The details for this hill were re-examined when the Ordnance Survey Vector Map Local hosted on the Geograph website and which is entitled the Interactive Coverage Map became available online.  This mapping has many spot heights not available on any other publicly available Ordnance Survey map.

The details for this hill were also re-assessed when the OS Maps website became available online.  This is the replacement for OS Get-a-map and has contours at 5m intervals which are proving consistently more accurate compared to the 5m contours that sometimes appear on Ordnance Survey 1:25,000 Explorer maps and the online Vector Map Local.  These re-assessments resulted in the hill being listed with an estimated c 24m of drop, based on an estimated summit height of c 328m and an estimated bwlch height of c 304m.

Extract from the OS Maps website

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.

The summit height produced by LIDAR analysis in comparison to the previously listed estimated summit 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 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 325.9m and this was produced by LIDAR analysis.  This is not a dramatic revision in height compared to some revised heights and is 2.1m lower than the previous estimated height of c 328m which was based on interpolation of the uppermost 320m ring contour on contemporary Ordnance Survey maps.


ills of Wales, and are reproduced below@
The full details for the hill are:

Group:  Carneddau

Name:  Dinas

OS 1:50,000 map:  115

Summit Height (New Height):  325.9m (LIDAR)

Summit Grid Reference:  SH 69978 73828 (LIDAR)

Bwlch Height:  301.5m (LIDAR)

Bwlch Grid Reference:  SH 70198 73941 (LIDAR)

Drop:  24.4m (LIDAR)


Myrddyn Phillips (November 2019)




Tuesday, 12 November 2019

Mapping Mountains - Hill Reclassifications - Y Pedwarau


Y Pedwarau – Hill Reclassifications

Y Pedwarau are the Welsh hills at or above 400m and below 500m in height that have a minimum drop of 30m.  Accompanying the main P30 list are five sub lists; these are the 500m Sub-Pedwar, 500m Double Sub-Pedwar, 400m Sub-Pedwar390m Sub-Pedwar and 390m Double Sub-Pedwar category’s, with their criteria detailed in the respective Change Registers that have been created and which are linked in their above titles, with the Introduction to this list being linked in the above title.

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








Mapping Mountains - Hill Reclassifications - Y Pedwarau

Y Gribin (SH 906 175) – 400m Sub-Pedwar reclassified to Pedwar (75th reclassification)


There has been a reclassification to the listing of Y Pedwarau due to LIDAR analysis initially conducted by Aled Williams and subsequently by Myrddyn Phillips, coupled with analysis of contemporary Ordnance Survey maps, including the 5m contouring on the OS Maps website, and Ordnance Survey data on the WalkLakes website.

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

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

Y Pedwarau – The 400m Hills of Wales.  Welsh hills at or above 400m and below 500m in height with 30m minimum drop, accompanying the main Y Pedwarau list are five categories of sub hills, with this hill being reclassified from the 400m Sub-Pedwar category.  The criteria for 400m Sub-Pedwar status being all Welsh hills at or above 400m and below 500m in height that have 20m or more and below 30m of drop.  The list is co-authored by Myrddyn Phillips and Aled Williams and is published on Mapping Mountains in Google Doc format.

The name of the hill is Y Gribin, and it is adjoined to the Y Berwyn group of hills, which are situated in the eastern part of North Wales (Region A, Sub-Region A4), and it is positioned with a minor road and the Afon Dyfi (River Dovey) to its west, and has the small community of Llanymawddwy towards the north.

This and its adjoining hill towards the south (which is also listed by the same name of Y Gribin) are both given a 485m summit spot height on contemporary Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer maps, and prior to this reclassification it was the southerly of these two hills (SH 902 172) that was prioritised for Pedwar status, whilst the northerly hill (SH 906 175) was listed as the 400m Sub-Pedwar.

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. 

The summit height produced by LIDAR analysis for the southerly of these two hills is 484.8m and is positioned at SH 90233 17288; however there is no LIDAR coverage for the northerly summit or the bylchau adjoined to each hill.

LIDAR summit image of the southerly of the two Y Gribin hills (SH 902 172)

The details for these two hills were then re-examined with contouring on the OS Maps website, this is the replacement for OS Get-a-map and has contours at 5m intervals.  The details for each hill were also examined via Ordnance Survey data on the WalkLakes website.  Lastly online logs that appear on the Hill Bagging website were consulted.  The data for each summit is given below:


Y Gribin

Ordnance Survey spot height:  485m (SH 902 172)

LIDAR: 484.8m summit at SH 90233 17288

OS Maps:  480m uppermost contour

WalkLakes spot height:  484m



Y Gribin

Ordnance Survey spot height:  485m (SH 906 175)

LIDAR:  not covered

OS Maps:  485m uppermost contour

WalkLakes website:  480m uppermost contour


There are two online logs of note on the Hill Bagging website, these have been posted by Anton Ciritus and Mick Moore and both make reference that in their view the northerly of these two summits is the higher.

Extract from the OS Maps website

Therefore, as evidence supports the northerly of the two Y Gribin summits to be the higher, this hill is reclassified from the 400m Sub-Pedwar to the Pedwar.

The reclassification of Y Gribin (SH 906 175) from 400m Sub-Pedwar to Pedwar status is due to a combination of factors, including LIDAR analysis, analysis of data on the OS Maps website and the WalkLakes website and online logs on the Hill Bagging website.  Therefore, with a 485m summit height that appears as a spot height on Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer maps and a 427m bwlch height that appears as a spot height on the Ordnance Survey 1:25,000 Explorer map, these values give this hill 58m of drop, which qualifies it for Pedwar status.


The full details for the hill are:

Group:  Y Berwyn 

Name:  Y Gribin

OS 1:50,000 map:  125

Summit Height:  485m (spot height)

Summit Grid Reference:  SH 90626 17580 (hand-held GPS via DoBIH)

Bwlch Height:  427m (spot height)

Bwlch Grid Reference:  SH 91702 17833 (spot height)

Drop:  58m


For the additions, reclassifications and deletions to Y Pedwarau reported on Mapping Mountains since the May 2013 publication of the list by Europeaklist please consult the following Change Registers:










Myrddyn Phillips and Aled Williams (October 2019)







Mapping Mountains - Hill Reclassifications - Y Pedwarau

Y Gribin (SH 902 172) – Pedwar reclassified to 400m Sub-Pedwar (74th reclassification)


There has been a reclassification to the listing of Y Pedwarau due to LIDAR analysis initially conducted by Aled Williams and subsequently by Myrddyn Phillips, coupled with analysis of contemporary Ordnance Survey maps, including the 5m contouring on the OS Maps website, and Ordnance Survey data on the WalkLakes website.

LIDAR image of Y Gribin (SH 902 172)

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

Y Pedwarau – The 400m Hills of Wales.  Welsh hills at or above 400m and below 500m in height with 30m minimum drop, accompanying the main Y Pedwarau list are five categories of sub hills, with this hill being reclassified to the 400m Sub-Pedwar category.  The criteria for 400m Sub-Pedwar status being all Welsh hills at or above 400m and below 500m in height that have 20m or more and below 30m of drop.  The list is co-authored by Myrddyn Phillips and Aled Williams and is published on Mapping Mountains in Google Doc format.

The name of the hill is Y Gribin, and it is adjoined to the Y Berwyn group of hills, which are situated in the eastern part of North Wales (Region A, Sub-Region A4), and it is positioned with a minor road and the Afon Dyfi (River Dovey) to its west, and has the small community of Llanymawddwy towards the north.

This and its adjoining hill towards the north (which is also listed by the same name of Y Gribin) are both given a 485m summit spot height on contemporary Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer maps, and prior to this reclassification it was the southerly of these two hills (SH 902 172) that was prioritised for Pedwar status, whilst the northerly hill (SH 906 175) was listed as the 400m Sub-Pedwar.

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

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. 

The summit height produced by LIDAR analysis for the southerly of these two hills is 484.8m and is positioned at SH 90233 17288; however there is no LIDAR coverage for the northerly summit or the bylchau adjoined to each hill.

LIDAR summit image of Y Gribin (SH 902 172)

The details for these two hills were then re-examined with contouring on the OS Maps website, this is the replacement for OS Get-a-map and has contours at 5m intervals.  The details for each hill were also examined via Ordnance Survey data on the WalkLakes website.  Lastly online logs that appear on the Hill Bagging website were consulted.  The data for each summit is given below:


Y Gribin

Ordnance Survey spot height:  485m (SH 902 172)

LIDAR: 484.8m summit at SH 90233 17288

OS Maps:  480m uppermost contour

WalkLakes spot height:  484m



Y Gribin

Ordnance Survey spot height:  485m (SH 906 175)

LIDAR:  not covered

OS Maps:  485m uppermost contour

WalkLakes website:  480m uppermost contour


There are two online logs of note on the Hill Bagging website, these have been posted by Anton Ciritus and Mick Moore and both make reference that in their view the northerly of these two summits is the higher.

Extract from the OS Maps website

Therefore, as evidence supports the northerly of the two Y Gribin summits to be the higher, the southerly summit is reclassified from the Pedwar to the 400m Sub-Pedwar.

Extract from the WalkLakes website

The reclassification of Y Gribin (SH 902 172) from Pedwar to 400m Sub-Pedwar status is due to a combination of factors, including LIDAR analysis, analysis of data on the OS Maps website and the WalkLakes website and online logs on the Hill Bagging website.  Therefore, with a 484.8m summit height ascertained from LIDAR analysis and an estimated bwlch height of c 462m taken from interpolation of 5m contouring on the OS Maps website, these values give this hill c 23m of drop, which qualifies it for 400m Sub-Pedwar status.


The full details for the hill are:

Group:  Y Berwyn

Name:  Y Gribin

OS 1:50,000 map:  125

Summit Height:  484.8m (LIDAR)

Summit Grid Reference:  SH 90233 17288 (LIDAR)

Bwlch Height:  c 462m (interpolation)

Bwlch Grid Reference:  SH 90496 17361 (interpolation)

Drop:  c 23m


For the additions, reclassifications and deletions to Y Pedwarau reported on Mapping Mountains since the May 2013 publication of the list by Europeaklist please consult the following Change Registers:










Myrddyn Phillips and Aled Williams (October 2019)







Mapping Mountains - Hill Reclassifications - Y Pedwarau

Moel yr Acre (SJ 169 526) – 400m Sub-Pedwar deletion (73rd reclassification)


There has been a deletion to the listing of Y Pedwarau due to analysis of data on the OS Maps website, which is the recent replacement for OS Get-a-map.

Moel yr Acre (SJ 169 526)

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

Y Pedwarau – The 400m Hills of Wales.  Welsh hills at or above 400m and below 500m in height with 30m minimum drop, accompanying the main Y Pedwarau list are five categories of sub hills, with this hill being deleted from the 400m Sub-Pedwar category.  The criteria for 400m Sub-Pedwar status being all Welsh hills at or above 400m and below 500m in height that have 20m or more and below 30m of drop.  The list is co-authored by Myrddyn Phillips and Aled Williams and is published on Mapping Mountains in Google Doc format.

The name of the hill is Moel yr Acre, and it is adjoined to the Bryniau Clwyd group of hills, which are situated in the north-eastern part of North Wales (Region A, Sub-Region A2), and it is positioned with the A525 road to its south, the B5429 road to its north-west and the B5431 road its north-east, and has the town of Rhuthun (Ruthin) towards the north-west.

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

Prior to analysis of data on OS Maps this hill was listed with c 20m of drop based on the 411.3m summit height ascertained from a Leica GS15 survey conducted by John Barnard and Myrddyn Phillips and an estimated bwlch height of c 391m based on interpolation of bwlch contouring between 390m – 395m on the Ordnance Survey 1:25,000 Explorer map.

Extract from the OS Maps website

The deletion of Moel yr Acre from 400m Sub-Pedwar status is due to the analysis of data on the OS Maps website and a re-assessment of bwlch contouring on the Ordnance Survey 1:25,000 Explorer map.  Therefore with a 411.3m summit height from the Leica GS15 survey and an estimated bwlch height of c 392m, based on bwlch contouring on OS Maps between 390m – 395m, this hill is now listed with c 19m of drop, which is insufficient for it to be classified as a 400m Sub-Pedwar. 


The full details for the hill are:

Group:  Bryniau Clwyd

Name:  Moel yr Acre

OS 1:50,000 map:  116

Summit Height:  411.3m (converted to OSGM15)

Summit Grid Reference:  SJ 16955 52668

Bwlch Height:  c 392m

Bwlch Grid Reference:  SJ 16994 53034 (interpolation)

Drop:  c 19m


For the additions, reclassifications and deletions to Y Pedwarau reported on Mapping Mountains since the May 2013 publication of the list by Europeaklist please consult the following Change Registers:










Myrddyn Phillips and Aled Williams (October 2019)







Mapping Mountains - Hill Reclassifications - Y Pedwarau

Bryn Hafod y Llan (SH 945 531) – 390m Double Sub-Pedwar addition (72nd reclassification)


There has been an addition of a hill to the list of the Y Pedwarau, with the summit height, bwlch height and their locations, the drop and status of the hill confirmed by LIDAR analysis initially conducted by Aled Williams and subsequently by Myrddyn Phillips.

LIDAR image of Bryn Hafod y Llan (SH 945 531)

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

Y Pedwarau – Welsh hills at or above 400m and below 500m in height with 30m minimum drop, accompanying the main Y Pedwarau list are five categories of sub hills, with this hill being included in the 390m Double Sub-Pedwar category.  The criteria for 390m Double Sub-Pedwar status being all Welsh hills at or above 390m and below 400m in height that have 20m or more and below 30m of drop.  The list is co-authored by Myrddyn Phillips and Aled Williams and is published on Mapping Mountains in Google Doc format.

The name of the hill is Bryn Hafod y Llan, and it is adjoined to the Mynydd Hiraethog group of hills, which are situated in the north-eastern part of North Wales (Region A, Sub-Region A2), and it is positioned with the A5 road to its south and the B4501 road to its east, and has the Alwen Reservoir to the north-east and the village of Cerrigydrudion towards the south. 

When the original 300m height band of Welsh P30 hills were published on Geoff Crowder’s v-g.me website this hill was not included in the Hills to be surveyed sub list that accompanied the main P30 list, as it did not meet the criteria then used for this sub category. 

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

After 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 18m of drop, based on an estimated summit height of c 397m and a bwlch height of 379m that appears as a spot height on the Ordnance Survey Vector Map Local hosted on the Geograph website and which is entitled the Interactive Coverage Map.

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

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. 

The addition of Bryn Hafod y Llan to 390m Double Sub-Pedwar status is due to LIDAR analysis, resulting in a 398.7m summit height and a 378.5m bwlch height, with these values giving this hill 20.1m of drop which is sufficient for it to be classified as a 390m Double Sub-Pedwar.


The full details for the hill are:

Group:  Mynydd Hiraethog

Name:  Bryn Hafod y Llan

OS 1:50,000 map:  116

Summit Height:  398.7m (LIDAR)

Summit Grid Reference:  SH 94590 53115 (LIDAR)

Bwlch Height:  378.5m (LIDAR)

Bwlch Grid Reference:  SH 94564 52682 (LIDAR)

Drop:  20.1m (LIDAR)


For the additions, reclassifications and deletions to Y Pedwarau reported on Mapping Mountains since the May 2013 publication of the list by Europeaklist please consult the available and following Change Registers:











Myrddyn Phillips and Aled Williams (September 2019)







Mapping Mountains - Hill Reclassifications - Y Pedwarau

Cefn Cyfarwydd (SH 752 630) – 500m Double Sub-Pedwar reclassified to 500m Sub-Pedwar (71st reclassification)

Survey post for Cefn Cyfarwydd


There has been a reclassification of a hill that is listed in the Y Pedwarau, with the summit height, bwlch height and their locations, the drop and status of the hill confirmed by a survey with the Trimble GeoXH 6000 conducted by Myrddyn Phillips and Aled Williams which took place on the 17th February 2019.

Cefn Cyfarwydd (SH 752 630)

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

Y Pedwarau – Welsh hills at or above 400m and below 500m in height with 30m minimum drop, accompanying the main Y Pedwarau list are five categories of sub hills, with this hill being reclassified from a 500m Double Sub-Pedwar to a 500m Sub-Pedwar.  The criteria for 500m Double Sub-Pedwar status being all Welsh hills at or above 500m and at or below 510m in height that have 20m or more and below 30m of drop, with the criteria for 500m Sub-Pedwar status being all Welsh hills at or above 500m and at or below 510m in height with 30m minimum drop.  The list is a joint compilation between Myrddyn Phillips and Aled Williams and is published on Mapping Mountains in Google Doc format.

The name of the hill is Cefn Cyfarwydd, and it is adjoined to the Carneddau 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 A5 road to its south and the B5106 and the A470 roads and the Afon Conwy to its east, and has the villages of Trefriw and Llanrwst towards the east.  

Prior to the survey with the Trimble GeoXH 6000 this hill was listed with 26m of drop based on the 503m summit and 477m bwlch spot heights that appear on the Ordnance Survey 1:25,000 Explorer map.

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

The details for this hill were re-assessed when the Ordnance Survey Vector Map Local hosted on the Geograph website became available online; this mapping is entitled the Interactive Coverage Map.  As this mapping is larger in format it enables a better judgement of interpolated heights and it occasionally has contours at 5m intervals compared to the 10m contour intervals normally shown on the 1:25,000 Explorer map.  However, this mapping has the same spot heights and 10m contouring as the 1:25,000 Explorer map and therefore the drop value for this hill remained listed as 26m.

The area taking in this hill was re-examined when the OS Maps website became available online.  This is the replacement for OS Get-a-map and has contours at 5m intervals.  This mapping shows the 477m bwlch spot height to be positioned on a separate 475m contour ring implying that the height of this hill’s bwlch is substantially lower than 477m, with interpolation based on this contouring giving the hill c 30m of drop.  But it was not until the survey with the Trimble GeoXH 6000 that the increased drop value was confirmed.

Extract from the OS Maps website

The reclassification of Cefn Cyfarwydd from 500m Double Sub-Pedwar status is due to a survey with the Trimble GeoXH 6000, resulting in a 501.7m summit height and a 471.0m bwlch height, with these values giving this hill 30.7m of drop which is sufficient for it to be classified as a 500m Sub-Pedwar.

The Trimble GeoXH 6000 gathering data at the summit of Cefn Cyfarwydd


The full details for the hill are:

Group:  Carneddau

Name:  Cefn Cyfarwydd

OS 1:50,000 map:  115

Summit Height:  501.7m (converted to OSGM15)

Summit Grid Reference:  SH 75201 63067

Bwlch Height:  471.0m (converted to OSGM15)

Bwlch Grid Reference:  SH 74708 62751

Drop:  30.7m


For the additions, reclassifications and deletions to Y Pedwarau reported on Mapping Mountains since the May 2013 publication of the list by Europeaklist please consult the available and following Change Registers:











Myrddyn Phillips and Aled Williams (July 2019)