Showing posts with label Maen Esgob. Show all posts
Showing posts with label Maen Esgob. Show all posts

Saturday, 24 August 2019

Mapping Mountains – Hill Reclassifications – Y Trichant


Maen Esgob (SH 748 759) – Sub-Trichant reclassified to Trichant

There has been a reclassification to a hill included in the listing of the Y Trichant, with the summit height, bwlch height and their locations, the drop and status of the hill initially confirmed by LIDAR analysis and subsequently by a survey with the Trimble GeoXH 6000 conducted by Myrddyn Phillips, with the latter taking place on the 22nd May 2019.

Maen Esgob (SH 748 759)

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

Y Trichant – 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 of the hill is Maen Esgob 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 and the coast to its north, and has the town of Conwy towards the north-east.

When the original 300m height band of Welsh P30 hills were published on Geoff Crowder’s v-g.me website this hill was included in the Hills to be surveyed sub list as it did not meet the criteria then used for the main P30 list; however the main P30 and accompanying sub list has now been standardised and interpolated heights and drop values also included.

When this list was standardised and interpolated heights also included this hill was listed with an estimated c 27m of drop, based on an estimated c 302m summit height and an estimated c 275m bwlch height, with each based on interpolation of 10m contouring on the contemporary Ordnance Survey 1:25,000 Explorer map.

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

The details for this hill were 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.  The mapping on OS Maps shows this hill as having seven continuous 5m contour rings, implying that the hill has at least 30m of drop.

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 image of Maen Esgob

The reclassification of this hill to Trichant status is due to LIDAR analysis, coupled with a subsequent Trimble GeoXH 6000 bwlch and summit survey, resulting in 30.6m of drop produced via LIDAR and a 300.0m summit height and a 269.2m bwlch height, with these values giving this hill 30.8m of drop produced via the Trimble GeoXH 6000 survey, with these values being sufficient for this hill to be classified as a Trichant.

 
The Trimble GeoXH 6000 gathering data at the summit of Maen Esgob

The full details for the hill are:

Group:  Carneddau

Name:  Maen Esgob

OS 1:50,000 map:  115

Summit Height:  300.0m (converted to OSGM15)

Summit Grid Reference:  SH 74877 75900

Bwlch Height:  269.2m (converted to OSGM15)

Bwlch Grid Reference:  SH 74870 75664 

Drop:  30.8m (converted to OSGM15)


For details on the survey of this hill

Myrddyn Phillips (August 2019)





Sunday, 21 July 2019

Mapping Mountains – Trimble Surveys – Carnedd Llywelyn


22.05.19  Maen Esgob (SH 748 759), Craig Celynnin (SH 746 733) and Cerrig y Ddinas (SH 754 739)

Cerrig y Ddinas (SH 754 739)

There are few places in Wales where two or more new P30s adjoined to one another are waiting to be found.  The north-eastern Carneddau is one such example, specifically the land adjoined to, and to the north-east of Tal y Fan, where three hills are situated that are potential new P30s; Maen Esgob, Craig Celynnin and Cerrig y Ddinas.

LIDAR analysis has helped in determining the P30 prospects of these three hills, and with Maen Esgob having broken through the magic P30 barrier all that remained was to confirm this with a Trimble survey.  The remaining two hills; Craig Celynnin and Cerrig y Ddinas have partial LIDAR coverage with Aled Williams having initially LIDARed the former’s bwlch and I then LIDARed the latter’s summit.  What was now required was a circuit of these three hills gathering Trimble bwlch and summit data for each.

There are limited parking places on the narrow roads leading in to these hills, but by 9.55am my car was squeezed off one of these lanes and I was heading on a track designated a public footpath leading to the house of Hafodty.

Some of the higher near hills were still blanketed by morning cloud caps, but otherwise conditions were perfect with a slight breeze and a comfortable walking temperature.  Beyond the house of Hafodty the track led to a path on upper grazing fields which soon came to another track which was my onward route toward Craig Celynnin after the planned survey of my first hill of the day; Maen Esgob.

Craig Celynin from the approach to Maen Esgob

The ten figure grid reference produced by LIDAR analysis for the bwlch of Maen Esgob zeroed me in to the position for Trimble placement, which was beside a greened track leading westward.  As the Trimble gathered data I walked further down the track to take a couple of photos of Llyn y Wrach, which today looked rather forlorn with dried outer edges and shallow water.

Gathering data at the bwlch of Maen Esgob

Llyn y Wrach

A good path led from the bwlch to the hill’s summit where before placing the Trimble on top of its flattish summit rock I tidied the remains of its cairn which had been pushed from its perch.  According to LIDAR this hill has 30.6m of drop and as such it means that Maen Esbob is Wales’ newest P30.

Gathering data at the summit of Maen Esgob

Once the Trimble had gathered its allotted data I packed it away and re-joined the greened track and followed it southward pausing at a stone circle on the way.  A number of these stones are now recumbent and embedded in the ground with two remaining uprights, one of which is tilted, but still looking impressive.

Maen Esgob from the approach to the stone circle

The most impressive of the monoliths

I passed a small herd of wild Carneddau ponies soon after and again stopped; these animals are always a joy to be near with their wildly wind-blown manes and dappled colouring.  Today the one that stood out was a brown foal who stood and watched me as I watched it framed by blackened burnt heather.

One of the wild Carneddau ponies

The greened track soon led me to a stream and then rising slopes toward the connecting bwlch of Craig Celynnin.  The critical point was again on a greened track, and after talking with a fell runner who was out scouting an upcoming event, I set the Trimble up and proceeded to gather its third data set of the day.

Gathering data at the bwlch of Craig Celynnin

Craig Celynnin is a potential new Pedwar and if it made the all-important 30m of drop it would be a fine addition to this list as its summit is crowned by a series of rocks, the highest of which soon had the Trimble aligned to its very highest point and individual datum points being gathered and stored.

By now the slight breeze of the morning had increased in strength, and as the Trimble gathered summit data on top of Craig Celynnin I sat on a near rock and looked out on this stunning part of Wales with breeze blown thoughts cascading through a contented mind.

Gathering data at the summit of Craig Celynnin

Leaving the summit I retraced my route back to the bwlch and continued around the northern part of Craig Celynnin on the greened track, only diverting from it in favour of a sheep path.  This led me to a walled greened track leading up and around to the old church of Llangelynnin, which nestles amongst the hills and almost merges with its landscape.

Llangelynnin

This church was mentioned in documents dated 1254, it breaths oldness and tranquillity, a place apart from modern day.  As I opened the heavy wooded door a sign above it made me smile. 

The sign above the front entrance

The interior transports back to a time and place now forgotten, with painting on the north wall of the chancel, including text and a skeletal figure looking rather ominous against the white washed interior walls.

Inside the old Church

I left and encountered increasing wind as the door was closed behind me.  A stoned ladder led over a near wall and gave access to the area of the connecting bwlch of my last hill of the day; Cerrig y Ddinas.  The bwlch was again beside a greened path, come track and as the Trimble slowly ebbed down to its 0.1m accuracy level before data should be logged, I sat on a near rock and luxuriated myself in the afternoon sunshine.  However, it took an age for this accuracy level to be attained, but once the 0.1m figure showed on the equipment’s screen I quickly pressed ‘Log’ and sat on my rock whilst data were gathered.

Gathering data at the bwlch of Cerrig y Ddinas

A path from the bwlch led around an intervening lump toward steepening slopes giving access to the rocky summit cone of Cerrig y Ddinas.  This consists of a huge rock tapered toward the customary drop, and by the time I arrived on its summit the breeze had developed to gusting wind, and with Trimble oblivion awaiting below the summit I set the equipment up aligned with the highest part of the summit rock, and attached it to its dog lead.  I use the dog lead as a safety precaution as it enables me to sit close to the Trimble and importantly below its internal antenna whilst data is gathered, and with the equipment attached to my hand via the lead, if it was blown off its airy perch I would be able to stop it tumbling to a rocky death many metres below.

The impressive summit rock of Cerrig y Ddinas

As the Trimble beeped away collecting its individual datum points I squeezed in to the rock below it and waited for the allotted data to be stored.  After taking a few photographs I gathered all my gear and made my way down to the leeward side of a near rock to sit and pack all necessary equipment away.

Gathering data at the summit of Cerrig y Ddinas

It was only a short walk from the summit retracing my inward route toward a fence, which gave access down grazing fields toward a gate and the narrow lane which led back to my car.  The walk had taken five hours with six data sets taken and three hills visited, with some interesting results pending!


Postscript:  Two out of three new P30s ain’t bad!



Survey Result:



Maen Esgob

Summit Height:  300.0m (converted to OSGM15)

Summit Grid Reference:  SH 74877 75900

Bwlch Height:  269.2m (converted to OSGM15)

Bwlch Grid Reference:  SH 74870 75664


Dominance:  10.26%





Craig Celynnin

Summit Height:  404.8m (converted to OSGM15) (significant height revision)

Summit Grid Reference:  SH 74667 73373

Bwlch Height:  377.1m (converted to OSGM15)

Bwlch Grid Reference:  SH 74604 73263

Drop:  27.7m

Dominance:  6.85%





Cerrig y Ddinas

Summit Height:  313.5m (converted to OSGM15)

Summit Grid Reference:  SH 75427 73948

Bwlch Height:  283.0m (converted to OSGM15)

Bwlch Grid Reference:  SH 75140 73786


Dominance:  9.73%