Mapping Mountains – Trimble Surveys – Cilfaesty

14.11.14  Caer Caradoc (SO 309 757), Stow Hill (SO 317 745) and Cwm Sannam Hill (SO 270 755)  

Caer Caradoc (SO 309 757) and Stow Hill (SO 317 745) left and right of  central background respectively

With the prospect of good weather and a number of hills no more than 45 minutes’ drive from Welshpool that I had not visited, I decided to head back into Shropshire and investigate some more of The Fours.  Ideally the three hills I’d chosen could be combined in a circular walk, but Google Maps indicated parking was limited, so I devised a route to the hills that required a there and back on a couple of occasions.

I parked outside a house at SO 286 754 having asked permission to do so.  As I set off heading eastward the last of the morning’s light drizzled showers passed over the land, once this sprinkling had disappeared the sun shone all day.  The green track I walked on was a quagmire of mud, sludge and water, heavy overnight rain had not helped.  This track led up towards Stow Hill which I wanted to visit after Caer Caradoc.  I left the track and climbed a gate into an adjacent field as the underfoot conditions were awful.

mmmmmmm yummy, a slushy, sludgy, slimy track

Once away from the mud laden track I slowly made my way up through a number of fields, each having access through a gate until nearing the earthen ramparts of Caer Caradoc, where a couple of fences and a hawthorn hedge had to be negotiated.

Caer Caradoc only entered the listing of The Fours on 27^th September 2013 as the old Ordnance Survey 1:50,000 map has a 403m spot height adjoined to the summit, this compared with a 399m spot height on current maps.  The old height had been rounded up from a 1,321.4ft (402.76m) levelled height that appeared on the Ordnance Survey 1:2,500 map. 

Approaching the summit of Caer Caradoc from the west one enters the ancient fortified structure through or close to the western gate.  The structure consists of three ramparts / ditches, all well preserved, these are impressive constructions with the outer one being approximately 5m high from the ditch’s base, the central one is about 6m high and the inner rampart is higher still and looks out from an approximate 9m from its ditch base to its top.

The inner embankment of Caer Caradoc

The view in the opposite direction looking up toward the high point of the hill on the inner embankment

The western approach is directly to the high point of this construction and the hill.  Unfortunately the day’s mileage and number of planned surveys dictated that I could not fully investigate the land around the ancient hill fort, but the high part of the hill looks out to its concentric earthen ramparts as they disappear eastward out of view.

I took two data sets from points about seven metres apart, with both being close in height to each other.  As the Trimble gathered data I looked south toward my next objective; Stow Hill, as sun caught the manicured green fields of its north-eastern slopes.  To the north-west the gentle rolling hills of Shropshire spread out with their contouring highlighted by light and shade from sun and shadow.

Trimble placed in position for the first summit data set

Trimble placed in position for the second summit data set

Before leaving the summit I looked down to the inner part of the summit area to where the 399m spot height appears on current maps, all land led upto the western rampart without any inner high point being visible.  Even if one existed, to list the summit as something approximately four metres below the height of the earthen rampart would make a mockery of where hill walkers head when they visit such places.  If wanting to visit the summit of the hill, few would be content in visiting the inner bowl of such a construction when significantly higher ground is immediately within reach.

The manicured green fields of Stow Hill

Leaving the summit I retraced my route back toward the sludge laden track and spent quite some time looking at the area of the critical col for Caer Caradoc.  This is in a field adjacent to a hedge and a feeding place for cattle, because of the latter the place where I thought the critical col is positioned was awash with mud and slime.  I found a relatively dry spot and gathered five minutes of data.

Gathering data at the col area of Caer Caradoc

As I left the field and walked up to re-join the track I looked down on where I had placed the Trimble and thought ground about 20 metres further east may be slightly higher and therefore a better place for the position of the col.  If time permitted I would re-visit on my descent and gather another data set.

The part of the green track I was now on was in much better condition than its lower counterpart.  Rutted through farm vehicle use it was relatively mud free, I walked on and beside it as it led up through a gap in two conifer plantations, the one to the south being extensive, whilst the northern one is only a narrow strip.  I followed the edge of the northerly plantation and walked on the ridge past an attractive pool which gave a good foreground to views of the upper part of Stow Hill and to the high Fforest Glud hills farther to the west.

The summit of Stow Hill is just beyond the conifer plantation

With the hills of Fforest Glud in the background

Once past another strip of conifer plantation the upper part of the hill is easily reached, this is marked by a trig pillar with adjacent ground one metre from the trig being the highest.  As the Trimble gathered data I happily soaked up the sun and took a number of photos.

Gathering data at the summit of Stow Hill

Re-tracing my steps back to the green track I met two walkers who had travelled from Telford for a 13 mile walk and were heading toward Black Hill (SO 326 790), we chatted for five minutes or so and then went our separate ways.  My way was back to the previously visited col for another data set before trying to keep off the lower part of the green track as the slithery mud swamp was not conducive to what constitutes a hill walk.  This meant I headed back into the adjacent fields and used gates between each, unfortunately progress was barred between two fields and the only way onward was through a hawthorn hedge which proved interesting.  As I lumbered my way into the hedge I did think about taking a photo as it isn’t every day that you find yourself willingly being immersed inside a hawthorn hedge. 

Once out onto the open field I gained the mud sludge track via a gate and walked back toward the car.  It was now 2.00pm and the first two hills and their respective surveys had taken four hours.  I crossed the road and continued on the green track, now more of a path which was adjacent to a hedge with a tarmacked road beyond leading to a house on my right.  I was now close to where the critical col for Cwm Sannam Hill is positioned.  The land immediately ahead looked quite flat, with hedgerows consisting of overhanging trees on the enclosed path and ground to my left which was scrub made up of small trees and bracken.  I reached a point where standing water continued from the path through the adjacent fence and onto the scrub land, this looked as if it indicated where the critical col is placed.  Making a mental note of the position for my return journey I continued on the path and then up through the lower mud splattered field to higher and dryer fields giving access to the high point of Cwm Sannam Hill.

The higher fields were now bathed by a lowering sun that cast rich colours and lengthy shadows.  I walked through one field full of horses that came toward me inquisitively; the next field brought me out by an old barn and another slime laden bog.  As I circumvented the bog a Red Kite flew across the outline of the hill and glided past in a southerly direction. 

The grassed summit ridge of Cwm Sannam Hill is crowned by a trig pillar on its southern periphery which has no height given to its flush bracket in the OS Trig Database.  However, whilst compiling The Fours we found an old 1,343ft (409.4m) height on the Ordnance Survey New Popular One-Inch map which complimented the height on the larger scaled 1:10,560 map; this height elevated the hill’s drop to 98m.  It’ll be interesting to find what the Trimble made of its summit and col height as with only another two metres of prominence the hill would become the latest addition to the Humps.

I assessed the ground leading upto the trig and decided that there were two possibilities for the high point, neither of them beside the trig.  One being approximately 14 metres from the trig and the other further away from it next to a fence corner, both positions were Trimbled.

Gathering data at the first of the two possible summit positions on Cwm Sannam Hill

Gathering data at the second of the two possible summit positions on Cwm Sannam Hill

Once the Trimble was safely packed away I re-traced my inward route back to the confines of the path and scrub land at the col.  I followed the patch of standing water from the path over a fence and into the wasteland of small trees and bracken and proceeded to wander around for five minutes.  It was hard to pinpoint where the valley to valley traverse met as the view was obstructed, it was also hard to judge where the western hill to hill traverse started to go up as the land was relatively flat.  However, I found a spot that I was happy with, gave it a large margin of uncertainty for positional height, gathered five minutes of data and made my way back to my car as the sun sank out of view and the land began to edge toward night.

Gathering data at the col area of Cwm Sannam Hill

Only one survey remained and that was the critical col for Stow Hill which was situated to the north of the summit of Cwm Sannam Hill, I had contemplated taking in this col on the walk but time dictated that it would be quicker to drive there.  So I jumped in my car drove the mile north to New Invention and headed west on narrow lanes to the col.  I’d investigated the position of the col on Google Maps the previous evening and thought that a car could be parked at the beginning of a track that led into a field on the south-western side of what looked like the position of the critical col.

When I arrived I parked on the track, grabbed all necessary gear and walked the few metres up the narrow road to look at the col.  It was one of the easiest I’ve had to judge since getting the Trimble, but unfortunately all land from the valley and the hill directions led me to the conclusion that the critical col for Stow Hill is placed in the centre of the narrow road.  I had hoped that if this was so that a placement on an adjacent grass verge would suffice, but the sides of each were raised above the road.  So taking the Trimble’s life in hand I set it up in the centre of the road and hoped that no vehicles would come this way for the next five to ten minutes.

Once logging data I decided to keep on the western side of the Trimble as from this side the road made its way toward the col around a slight corner and if any vehicle approached from this direction I wouldn’t have much time to either stop it or grab the Trimble, whereas on the eastern side the road climbed steeply up toward the col and therefore I may have time to grab it before its strength was tested against another car.

Two minutes into data collection and I heard the sound of a car which came from the western side of the col, as it approached I flagged it down and quickly explained what I was doing and asked if they would mind waiting about three minutes until it had done its stuff.  They kindly said that this was no problem and waited, this meant I could run past the Trimble and stand on its eastern side and stop any vehicle approaching from that direction, thankfully none did and once five minutes of data were collected I packed the Trimble away, thanked the occupants of the car and explained in more detail what the Trimble did and possibly more relevant; the reasoning why.

Living dangerously - the Trimble gathering data in the middle of the road at the critical col of Stow Hill

As I got back into my car the last light of the day was quickly disappearing to be overtaken by the blueness of late autumnal dusk.  The hills of Shropshire are proving an excellent addition to my hill walking agenda.  I must visit more during the winter months.

Postscript:

Since the survey of these hills full LIDAR coverage is now available.  The LIDAR (Light Detection & Ranging) technique produced highly accurate height and positional data that is now freely available for England and Wales.  Consequently the numerical details for these hills have been analysed using this technique, resulting in the LIDAR height and position for some of these hills being prioritised over that produced by the Trimble GeoXH 6000.

Survey Result:


Caer Caradoc 

Summit Height:  402.7m (converted to OSGM15, Trimble GeoXH 6000)

   

Summit Grid Reference:  SO 30903 75743 (Trimble GeoXH 6000)

Col Height:  346.9m (LIDAR)

Col Grid Reference:  SO 29782 75096 (LIDAR)

Drop:  55.8m (Trimble GeoXH 6000 summit and LIDAR col) 

Dominance:  13.86% (Trimble GeoXH 6000 summit and LIDAR col) 

Stow Hill 

Summit Height:  434.3m (converted to OSGM15)

   

Summit Grid Reference:  SO 31758 74527

Col Height:  299.1m (converted to OSGM15)

Col Grid Reference:  SO 26949 76843

Drop:  135.2m 

Dominance:  31.13%

Cwm Sannam Hill (significant name change)

Summit Height:  409.1m (converted to OSGM15, Trimble GeoXH 6000)

   

Summit Grid Reference:  SO 27080 75511 (Trimble GeoXH 6000)

Col Height:  310.0m (LIDAR)

Col Grid Reference:  SO 28540 75409 (LIDAR)

Drop:  99.1m (Trimble GeoXH 6000 summit and LIDAR col)  

Dominance:  24.23% (Trimble GeoXH 6000 summit and LIDAR col)

 

For further details please consult the Trimble Survey Spreadsheet