Mapping Mountains – Significant Height Revisions – 600m Twmpau and The Welsh Highlands - Uchafion Cymru

Cnicht (SH 645 466)

There has been a Significant Height Revision to a hill that is listed in the 600m Twmpau and the The Welsh Highlands – Uchafion Cymru, with the summit height, bwlch height and their locations, the drop and status of the hill derived from a Trimble GeoXH 6000 survey conducted by Myrddyn Phillips.

Cnicht (SH 645 466)

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

600m Twmpau – Welsh hills at or above 600m and below 700m in height that have 30m minimum drop, with an accompanying sub category entitled the 600m Sub-Twmpau consisting of all Welsh hills at or above 600m and below 700m in height that have 20m or more and below 30m of drop.  The list is authored by Myrddyn Phillips, with the word Twmpau being an acronym standing for thirty welsh metre prominences and upward.

The 600m Twmpau by Myrddyn Phillips

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.  Accompanying the main list are three sub lists, these are; 500m Sub-Uchaf, 490m Sub-Uchaf and the Double Sub category.  The list is co-authored by Myrddyn Phillips and Aled Williams with the Introduction to the list published on Mapping Mountains in November 2015 and an update relating to the list appearing on Mapping Mountains on the 19^th June 2019.

The Welsh Highlands - Uchafion Cymru by Myrddyn Phillipa and Aled Williams

The name the hill is listed by is Cnicht, and it is adjoined to the Moelwyn Mawr 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 A4085 road to its south-west, the A498 road to its north-west and the A470 road to its east, and has the small community of Croesor towards the south-west and the town of Blaenau Ffestiniog towards the east.

Prior to the Trimble GeoXH 6000 survey this hill was listed with an estimated c 106m of drop, based on the 689m summit spot height that appears on the Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer map, and an estimated c 583m bwlch height, based on interpolation of 10m contouring between 580m - 590m.

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

The summit height produced by the Trimble GeoXH 6000 survey is 690.7m, this is not a substantial height revision when compared to some revised heights, but it does come 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, Harvey or other interactive 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 with the data produced by the Trimble or by LIDAR analysis.

The Trimble GeoXH 6000 gathering data at the summit of Cnicht

Therefore, the new listed summit height of this hill is 690.7m and this was derived from a Trimble GeoXH 6000 survey.  This is 1.7m higher than its previously listed summit height of 689m which appears as a spot height on the Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer map.  However, this new height is in accordance with the 5m contouring on OS Maps. 

 

Extract from the OS Maps website

ills of Wales, and are reproduced below@

The full details for the hill are:

Group:  Moelwyn Mawr

Name:  Cnicht

OS 1:50,000 map:  115

Summit Height (New height):  690.7m (converted to OSGM15)

Summit Grid Reference:  SH 64545 46613 

 

Bwlch Height:  585.7m (converted to OSGM15)

Bwlch Grid Reference:  SH 65589 47707

Drop:  105.0m

Myrddyn Phillips and Aled Williams (July 2019)

Mapping Mountains – Trimble Surveys – Moelwyn Mawr

23.03.19  Cnicht (SH 645 466) and Pt. 690.2m (SH 647 468)

Cnicht (SH 645 466)

Cnicht is rightly considered one of the iconic mountains of Wales; it rises above the small community of Croesor in a steep pyramidal and eloquent shape.  However, this view hides its extended north-eastern ridge that descends in grassed slopes toward the tranquil surrounds of Llyn yr Adar.

Many years ago it seemed as if I almost lived on this hill having visited it already on a number of occasions, as when its north-easterly top was promoted to Nuttall status in spring 1997 it meant many more visits to its ever appealing summit to bring my Welsh Nuttall total up-to-date.  However, those times are now long gone, and it has been nine years since I last visited.

Four of us set out from the car park in Croesor and with a forecast of dry conditions with hazy sunshine the day ahead was one to enjoy.  Two of our party; Abi and Ann-Marie had Mountain Leadership qualification so any semblance of navigational skill that I may possess was happily put to one side for the day.

Heading toward the hill

As height was gained the profile of Cnicht was forever in view, with tiny figures of people on its upper slopes and summit adding perspective to the scene.  We had a number of stops enjoying the intermittent sunshine and early spring warmth, during which I took the opportunity to set off ahead slowly plodding my way up the ridge knowing that Jude, Abi and Ann-Marie would catch me up before the summit, and so they did, just before the last steep section.

The summit of Cnicht consists of a number of up thrust small rocks with the central of three our candidate for the highest and within a few minutes of arriving on the summit the Trimble was aligned with the highest bit of rock and quietly beeping away collecting its individual datum points.

Gathering data at the summit of Cnicht

During data collection the girls sat just below the summit with Ann-Marie seemingly seated on the edge of the world from the vantage point I stood at, once the last of the allotted data were gathered and stored I closed the equipment down and we headed on the continuation of the ridge to the bwlch between the main and subsidiary peak of Cnicht.

Ann-Marie perched on the edge of the world

Ann-Marie, Jude and Abi at the summit of Cnicht

This bwlch is easily identified and the Trimble was soon positioned on top of my rucksack and the offset between its internal antenna and the ground below measured and noted.  It remained there for six minutes gathering its all-important data.

The Trimble set-up position at the bwlch of the subsidiary peak of Cnicht

Moelwyn Mawr

Gathering data at the bwlch for the subsidiary peak of Cnicht

The ridge path continues north-eastward and bisects at the base of the next top, with one branch bi-passing the uphill section, whilst the other climbs through rock toward the summit of this next hill.

Jude heading toward the summit of the second hill of the day

This hill has an untidy flattish cairn signifying its summit, these few rocks were soon removed and with the ground below now exposed we could determine its very highest point, which proved to be about 0.75 of a metre from where the untidy cairn had obliterated and messed an otherwise natural scene.

Again the Trimble was placed with its internal antenna aligned with the summit and it remained in place for the next eleven minutes gathering data as the four of us sat and chatted.  During this a few people walked the ridge from Cnicht and none visited the point where the Trimble beeped away gathering its third data set of the day.

Gathering data at the subsidiary peak of Cnicht

The last survey of the day was the critical bwlch of Cnicht which is placed overlooking Llyn yr Adar.  The broad north-eastern ridge descending from Cnicht soon turns in to moor grass and its path leads direct down to this bwlch.

Within a few minutes the Trimble was placed on top of my rucksack and it was gathering its last data set of the day.  As I stood away from the equipment Canada geese skimmed across the near lake giving a backdrop with their wagh-onk call piecing an otherwise quiet scene.

Gathering data at the critical bwlch of Cnicht

All that remained was the walk back via a boggy path leading down to the abandoned workings of the Rhosydd Quarry and the continuation below the Croesor Quarry to the valley below.  Once back at the car and changed we headed south toward Cross Foxes where Ann-Marie’s husband; Mark joined us for a good meal before heading home, a great way to end the day. 

        

Survey Result:

Cnicht

Summit Height:  690.7m (converted to OSGM15) (significant height revision)

Summit Grid Reference:  SH 64545 46613

Bwlch Height:  585.7m (converted to OSGM15)

Bwlch Grid Reference:  SH 65589 47707

Drop:  105.0m

Dominance:  15.20%

Pt. 690.2m

Summit Height:  690.2m (converted to OSGM15) (significant height revision)

Summit Grid Reference:  SH 64799 46864

Bwlch Height:  670.9m (converted to OSGM15)

Bwlch Grid Reference:  SH 64681 46742

Drop:  19.3m

Dominance:  2.79%

For further details please consult the Trimble Survey Spreadsheet