Showing posts with label Carreg Croes Ifor. Show all posts
Showing posts with label Carreg Croes Ifor. Show all posts

Saturday, 18 February 2023

Mapping Mountains – Trimble Surveys – Cefn yr Ystrad


06.01.23  Blorens (SO 269 118), Carreg Croes Ifor (SO 246 107) and Carreg Croes Ifor (SO 248 106) 

Blorens (SO 269 118)

Today was a special occasion as Mark Trengove completed the Deweys.  These are the English, Manx and Welsh hills between 500m – 609.6m (2,000ft) in height that have a minimum 30m prominence.  The list was compiled by Michael Dewey who sadly passed away in November last year.

Mark had chosen Blorens as his final hill in this list.  This hill forms a large bulk when viewed from the valley below, however a relatively easy ascent from one of two high car parks beside the road passing over the hills heading south toward Blaenafon eases passage to the summit.  This was the route Mark suggested for us to use.

List completions are always special occasions, they are the culmination of what can be many years wandering the uplands visiting all hills in a designated area that meet a set criteria.  My Welsh Dewey completion was celebrated on the summit of Graig Goch (SH 715 085) in August 2003, I did wonder if I would continue and start in earnest on the English Deweys, however that was not to be.  For me the Welsh Deweys took a number of years to complete, it is almost double the effort to then go on and complete the full list with the English and Manx hills also thrown in for good measure.

The forecast for the day gave a window of dry weather from late morning through to late afternoon.  However, as we travelled south the rain poured down.  Thankfully by the time we navigated our way on to the mountain road that heads up toward our designated car park the sky, although still slate grey, had at least relented in its wet downpour.

When we arrived at the car park beside the Pen-ffordd-goch Pond there were already a number of cars there, with dog walkers heading this way and that, and adventurous wild water swimmers braving the cold depths of the lake.

From here our proposed route skirted the western fringe of the lake on a good path that contoured its way around the hill.  As we walked beside the lake the upper bulk of Blorens looked back down at us with its heather clad slopes giving a sense of wildness to the scene.  This was at odds with the convenience of the car park and the good gravelled path we started out on.  However, the hill is certainly wild and today also windswept. 

Aled and Mark on the path heading toward Blorens

The path gave good views back toward the ravaged industrialised slopes of Carreg Croes Ifor, a double summited hill that Mark and Aled planned on visiting after Blorens.  Across the intervening land to our west was also Pen Carn Llwyd (SO 244 125) a 400m Sub-Pedwar that today looked inviting in its rusted coloured winterness. 

Pen Carn Llwyd (SO 244 125)

As the main path continued around the northern section of the hill we veered right on to a narrower path heading up toward the summit.  I slowly followed Aled and Mark as steady progress was made, even small patches of blue in the sky were becoming evident to greet us as we reached the upper boulders of the summit area.

The high point of Blorens comprises a few embedded rocks about 20 metres from a triangulation pillar.  On the other side of the trig pillar is an ancient cairn now hollowed out to incorporate a windshelter.  Mark approached the trig pillar and was greeted with the customary handshake and congratulations.  It’s a fine achievement completing the Deweys and Mark is one of only a few people to do so; therefore he is in rarefied company. 

Mark in celebratory mode at the trig pillar of Blorens

We stayed on the summit for quite some time with gin and cake as accompaniment.  During this Aled Abneyed the summit to confirm the highest point and afterward set the Trimble up to gather data.  We let the equipment chug away gathering about ten minutes of data as we tucked in to our drink and food goodies. 

Aled with our celebratory goodies

Gathering data at the summit of Blorens

During our time on the summit the weather was positively sumptuous compared to our journey south, however the forecast was for more heavy rain setting in by 5.00pm, so however good the summit celebrations were we now needed to contemplate heading down.  Therefore, once the Trimble had gathered data and was safely packed away we followed another good path down the broad south-western ridge of the hill that led us to the second car park where two high masts are positioned.  From here it was only a short walk back on a narrow road to the awaiting car. 

Heading down from the summit of Blorens

It was here that Mark and Aled headed toward Carreg Croes Ifor, and as I’d developed a chest infection over Christmas and New Year which still hampered me, I was happy enough with visiting just one hill and headed back to the car to change in to dry clothes.

Back at the car I looked up toward the upper part of Carreg Croes Ifor and spotted Mark and Aled near the summit.  I’d been on this hill once before when out on a multi-hill bagging day, squeezing in the easiest ascent for each hill.  I remember its summit area comprising a number of rounded tops and it was two of these that Aled wanted to visit and survey. 

Mark at the summit of the higher of the two Carreg Croes Ifor tops (Photo: Aled Williams)

After getting changed I repositioned my car at the end of the track leading down from Carreg Croes Ifor and waited for Mark to arrive.  He’d visited the higher of the two summits and left Aled heading toward the lower to survey it.

Gathering data at the lower of the two Carreg Croes Ifor tops (Photo: Aled Williams)

Once Aled had surveyed the summit of the lower peak, he headed back to the higher main summit and gathered another data set with the Trimble.  By this time the sky to the south had turned an ominous colour with the incoming rain an hour ahead of the forecast.  This started as wind-blown flecks, but by the time Aled had packed the Trimble away and headed down the track toward the car it just started to rain in earnest.  

The higher of the two Carreg Croes Ifor tops from the lower summit (Photo: Aled Williams)

We had been lucky with the weather as conditions had given us time to suitably celebrate Mark’s achievement of completing the Deweys.  It had also given Aled sufficient time to survey the three summits and just get back to the car before getting too wet. 

View toward the lower of the two Carreg Croes Ifor tops (Photo: Aled Williams)

On our way back it continued to rain, but we also continued our celebratory theme with a stop off at the Wheelwright Arms in Erwyd (Erwood) for a couple of hours conversation over good pub grub beside a welcome warmed wood burner.  A lovely way to end a special day. 

 

Survey Result:

 

Blorens

Summit Height:  558.9m (converted to OSGM15) (Trimble GeoXH 6000) (significant height revision)

Summit Grid Reference:  SO 26974 11830 (Trimble GeoXH 6000)

Bwlch Height:  426.9m (LIDAR)

Bwlch Grid Reference:  SO 21949 10939 (LIDAR)

Drop:  132.0m (Trimble GeoXH 6000 summit and LIDAR bwlch)

Dominance:  23.62% (Trimble GeoXH 6000 summit and LIDAR bwlch)

 

 

Carreg Croes Ifor

Summit Height:  507.1m (converted to OSGM15) (Trimble GeoXH 6000)

Summit Grid Reference:  SO 24681 1061 (Trimble GeoXH 6000)

Bwlch Height:  494.3m (LIDAR)

Bwlch Grid Reference:  SO 24777 10719 (LIDAR)

Drop:  12.7m (Trimble GeoXH 6000 summit and LIDAR bwlch)

Dominance:  2.51% (Trimble GeoXH 6000 summit and LIDAR bwlch)

 

 

Carreg Croes Ifor

Summit Height:  509.7m (converted to OSGM15) (Trimble GeoXH 6000) (significant height revision)

Summit Grid Reference:  SO 24848 10663 (Trimble GeoXH 6000) (summit relocation)

Bwlch Height:  482.1m (LIDAR)

Bwlch Grid Reference:  SO 25485 10565 (LIDAR)

Drop:  27.6m (Trimble GeoXH 6000 summit and LIDAR bwlch)

Dominance:  5.42% (Trimble GeoXH 6000 summit and LIDAR bwlch)


 

For further details please consult the Trimble Survey Spreadsheet

 

 

 

 

 

 

  

Monday, 4 May 2020

Mapping Mountains – Significant Height Revisions – 500m Twmpau and The Welsh Highlands – Uchafion Cymru


Carreg Croes Ifor (SO 248 106)

There has been a Significant Height Revision to a hill that is listed in the 500m Twmpau and The Welsh Highlands – Uchafion Cymru, with the summit height, bwlch height and their locations, the drop and status of the hill confirmed by LIDAR analysis and a subsequent Trimble GeoXH 6000 summit survey conducted by Aled Williams.

LIDAR image of Carreg Croes Ifor (SO 248 106)

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

500m Twmpau – Welsh hills at or above 500m and below 600m in height that have 30m minimum drop, with an accompanying sub category entitled the 500m Sub-Twmpau consisting of all Welsh hills at or above 500m and below 600m in height that have 20m or more and below 30m of drop.  With the word Twmpau being an acronym standing for thirty welsh metre prominences and upward.  The list is authored by Myrddyn Phillips and is published on Mapping Mountains in Google Doc format.

The Welsh Highlands – Uchafion Cymru This is the revised draft title for the Welsh 500m P15s list that takes in all hills in Wales at or above 500m in height with 15m minimum drop.  The list is co-authored by Myrddyn Phillips and Aled Williams with the Introduction to the list being published on Mapping Mountains in November 2015 and an update relating to the list appearing on Mapping Mountains on the 19th June 2019.

The name the hill is listed by is Carreg Croes Ifor and it is adjoined to the Cymoedd Gwent group of hills, which are situated in the eastern part of South Wales (Region C, Sub-Region C2), and it is positioned with the A465 road to its north, the B4248 road to its south-west and the B4246 road to its east, and has the town of Blaenafon towards the south south-east.

When the original list of Welsh 500m P15s that later became known as Yr Uchafion and latterly as The Welsh Highlands – Uchafion Cymru was first compiled, this hill was listed with an estimated c 18m of drop based on a non-interpolated c 500m summit height and a 482m bwlch height taken from the spot height that appears on the Ordnance Survey 1:25,000 Explorer map.

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

Since first compilation of the Welsh 500m P15 list there are a number of maps now available online, and the details for this hill were re-assessed when the Ordnance Survey 1:25,000 Historical map became available online, and this map gives a 1657ft (505.1m) summit spot height for this hill.

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

The imperial height on the Ordnance Survey 1:25,000 Historical map is derived from a 1657.4m (505.2m) Surface Height that appears on the Ordnance Survey series of Six-Inch maps.  Therefore, the summit height for this hill was revised and listed as 505m with the caveat that since this height was derived this hill has undergone mining activity which has substantially altered the landscape.

Extract from the Ordnance Survey series of Six-Inch maps

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 summit image for Carreg Croes Ifor

The summit height and position produced by LIDAR analysis is 509.8m at SO 24848 10663, this is a dramatic height revision when compared to some revised heights, and it 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 summit 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.

During analysis of this hill, Aled used overlays from old maps with contemporary maps and the details produced via LIDAR.  This shows that the natural 505.2m summit positioned at SO 24810 10620 is now under a substantial amount of mine spoil and this has raised the height of the summit. 

The summit of this hill has now been surveyed with the Trimble GeoXH 6000 and as the natural summit is now under a spoil tip and an on-site visit confirms this artificially raised summit to be solid and stable, it is the Trimble summit height and position that is being prioritised for this hill.     

Therefore, the new listed summit height of this hill is 509.7m and this was derived from a Trimble GeoXH 6000 survey, this is 4.7m higher than the 505m summit height that was previously given for this hill. 


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

Group:  Cymoedd Gwent

Name:  Carreg Croes Ifor

OS 1:50,000 map:  161

Summit Height (New Height):  509.7m (converted to OSGM15, Trimble GeoXH 6000, artificially raised)

Summit Grid Reference:  SO 24848 10663 (Trimble GeoXH 6000) 
 
Bwlch Height:  482.1m (LIDAR)

Bwlch Grid Reference:  SO 25485 10565 (LIDAR)

Drop:  27.6m (Trimble GeoXH 6000 summit and LIDAR bwlch)


Aled Williams and Myrddyn Phillips (May 2020)





Sunday, 26 April 2020

Mapping Mountains – Summit Relocations – 500m Twmpau and The Welsh Highlands – Uchafion Cymru


Carreg Croes Ifor (SO 248 106)

There has been a Summit Relocation to a hill that is listed in the 500m Twmpau and The Welsh Highlands – Uchafion Cymru, with the summit height, bwlch height and their locations, the drop and status of the hill confirmed by LIDAR analysis and a subsequent Trimble GeoXH 6000 summit survey conducted by Aled Williams.

LIDAR image of Carreg Croes Ifor (SO 248 106)

The criteria for the two listings that this summit relocation applies to are:

500m Twmpau – Welsh hills at or above 500m and below 600m in height that have 30m minimum drop, with an accompanying sub category entitled the 500m Sub-Twmpau consisting of all Welsh hills at or above 500m and below 600m in height that have 20m or more and below 30m of drop.  With the word Twmpau being an acronym standing for thirty welsh metre prominences and upward.  The list is authored by Myrddyn Phillips and is published on Mapping Mountains in Google Doc format.

The Welsh Highlands – Uchafion Cymru This is the revised draft title for the Welsh 500m P15s list that takes in all hills in Wales at or above 500m in height with 15m minimum drop.  The list is co-authored by Myrddyn Phillips and Aled Williams with the Introduction to the list being published on Mapping Mountains in November 2015 and an update relating to the list appearing on Mapping Mountains on the 19th June 2019.

The name the hill is listed by is Carreg Croes Ifor and it is adjoined to the Cymoedd Gwent group of hills, which are situated in the eastern part of South Wales (Region C, Sub-Region C2), and it is positioned with the A465 road to its north, the B4248 road to its south-west and the B4246 road to its east, and has the town of Blaenafon towards the south south-east.

When the original list of Welsh 500m P15s that later became known as Yr Uchafion and latterly as The Welsh Highlands – Uchafion Cymru was first compiled, this hill was listed with an estimated c 18m of drop based on a non-interpolated c 500m summit height and a 482m bwlch height taken from the spot height that appears on the Ordnance Survey 1:25,000 Explorer map.

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

Since first compilation of the Welsh 500m P15 list there are a number of maps now available online, and the details for this hill were re-assessed when the Ordnance Survey 1:25,000 Historical map became available online, and this map gives a 1657ft (505.1m) summit spot height for this hill.

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

The imperial height on the Ordnance Survey 1:25,000 Historical map is derived from a 1657.4m (505.2m) Surface Height that appears on the Ordnance Survey series of Six-Inch maps.  Therefore, the summit height for this hill was revised and listed as 505m with the caveat that since this height was derived this hill has undergone mining activity which has substantially altered the landscape.

Extract from the Ordnance Survey series of Six-Inch maps

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 summit image for Carreg Croes Ifor

The summit height and position produced by LIDAR analysis is 509.8m at SO 24848 10663, and this position in relation to that previously given 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 it is positioned to a different feature such as in a conifer plantation, or when the high point of the hill is placed within a different map contour compared to its previous listed position, or when natural ground or 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.

During analysis of this hill, Aled used overlays from old maps with contemporary maps and the details produced via LIDAR.  This shows that the natural 505.2m summit positioned at SO 24810 10620 is now under a substantial amount of mine spoil and this has raised the height of the summit. 

The summit of this hill has now been surveyed with the Trimble GeoXH 6000 and as the natural summit is now under a spoil tip and an on-site visit confirms this artificially raised summit to be solid and stable, it is the Trimble summit height and position that is being prioritised for this hill.     

Therefore, the new listed summit height for this hill is 509.7m and is positioned at SO 24848 10663, this position is not given a spot height on the contemporary Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer map and is approximately 160 metres westward from where the previously listed summit is positioned. 


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

Group:  Cymoedd Gwent

Name:  Carreg Croes Ifor

OS 1:50,000 map:  161

Summit Height:  509.7m (converted to OSGM15, Trimble GeoXH 6000, artificially raised)

Summit Grid Reference (New Position):  SO 24848 10663 (Trimble GeoXH 6000) 
 
Bwlch Height:  482.1m (LIDAR)

Bwlch Grid Reference:  SO 25485 10565 (LIDAR)

Drop:  27.6m (Trimble GeoXH 6000 summit and LIDAR bwlch)


Aled Williams and Myrddyn Phillips (May 2020)