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All triangulation pillars, points and benchmarks appear on or near the walks in Dark Peak Walks published by Cicerone Press and available HERE
Identify each Ordnance Survey triangulation pillar or triangulation point. Name of triangulation pillar and grid reference required. Also which one is the odd one out. Wins a Wapentac Map’n’lite of Froggatt Edge
Alphin Pike Triangulation Pillar
Ordnance Survey Triangulation Points and Triangulation Pillars
Identify location of each Ordnance Survey benchmark or survey mark . Grid reference would be superb. Wins a signed gift wrapped copy of Dark Peak Walks. Closest answers will win.
In the 1700’s the first baseline for triangulation was measure on Hounslow Heath. It first used wooden then iron and finally glass rods for better accuracy to measure the baseline of the first triangle. Subsequent triangulations formed new baselines, then in 1936 a whole new system of triangulation was developed by Ordnance Survey along with a whole new set of markers on the ground for the triangulation points.
The last triangulation of Britain took place between 1935 and 1962 with the now familiar triangulation pillar being used for the first time. Along with the pillars there were several other types of markers employed for the survey points.
Buildings were often used, especially ones which would not probably be pulled down in the future, churches were a favourite, Bakewell was one, as was the Hunting Tower and its flagstaff on the Chatsworth estate.
Fundamental Benchmarks were the cornerstone of the whole system, these were protected by iron fencing. The FBM as they were known were seated on bedrock and were used as definitive levelling points as the one on the Mortimer Road on Broomhead Moor.
Surface Blocks like the one at Hollingworth Head, there is also one near Big Moor formed part of the triangulation measurements. They lie close to the surface but are hard to find as they are often covered with grass. Even harder to find are Surface Bolts such as the Laddow Rocks one. It is amazing that a small bolt has survived all this time.
And sometimes a triangulation point just isn’t one. This is the case of the Hey Edge Pillar which is marked on the map as a Pillar, but does not have the blue triangle on the map. That is because whilst it was built it was never used for triangulation. It was used for levelling, but as I have said that is a totally different set of measurements. Hence it does not qualify as a trig point to Ordnance Survey.
Nowadays with GPS triangulation by hand is no longer required and the Ordnance Survey network of triangulation points is falling in to disuse, apart from a few that is. The Triangulation Pillar at Harland South forms part of the Global Positioning System network, as does the Fundamental Benchmark on Broomhead Moor. So even though GPS is now the dominant measuring system for position, it still relies on spots on the ground for accuracy.
There are quite a few bits of survey ephemera along Cut Gate in the Dark Peak. Benchmarks are much in evidence if you know where to look.
Just above the words “Lost Lad” on the 1852 Ordnance Survey map of Cut Gate, high above Langsett, there are two benchmarks denoted, the B.M followed by the elevation above Mean Sea Level in feet. Mean Sea Level in them days was taken from the measurements obtained at the Liverpool Datum, whereas today it is Newlyn. The first Benchmark happens just before the ford which is the turn off point for the spot height on Lost Lad itself. It is simple arrow beneath a line, but unusually is on a flat surface and not a vertical one, making it a little difficult to be accurate in the measurement. It is also accompanied by the initials RW, Rimmington Wilson the then landowner, chiselled at a later date and certainly with not as much skill.
Heading down the Cut Gate path towards Langsett a further benchmark can be found on the gate post of the boundary wall at Hingcliff Common.
Grouse had been introduced onto the moors for several decades when the benchmark was carved so it would have looked pretty much the same as today with one exception. The Cut Gate track went through the gate posts where as today the line of the path goes someway to the south-east.
A surveying team would consist of a surveyor and his assistant. The surveyor took the reading and the assistant held the staff and lugged the equipment around. It was the surveyor who chiselled in the benchmark. I often try to imagine the team out in all weathers mapping the area. Around these two benchmarks are many more plus triangulation points on Hingcliff Hill and Pike Lowe to the east. The maps they produced are remarkably accurate and can still be followed today on the ground. The really interesting thing about old maps are the items marked that are no longer on modern-day maps.
Yesterday I spent a few hours on Hathersage Moor and Higger Tor seeing if any benchmarks shown on old maps would still be evident today.
The image from the old map above is taken from a survey of the Moor carried out in 1852. Would the benchmarks shown still be there, did they actually exist or were they just markings on the map showing where a measurement had been taken from? What did they actually look like?
The one on Higger Tor, (Higher Tor), seemed to be the easiest to find. It’s the small arrow between the ‘r’ and ‘T’ of ‘Higger Tor’. The marking is not to scale obviously, nearby there is a triangle denting a triangulation point. It also has lots of features to aim from and sure enough that’s how it turned out. It took a while of rummaging around and at first I was looking for a benchmark on a vertical surface and chiselled in the style that is normally seen on buildings and gate posts. Then I found it, on a large flat stone, in the middle of the edge path. The marking was on a horizontal surface and pointed west, not north as in the map. It was a simple arrow with no levelling line at the tip of the arrow. The mark was still very clear, although if you weren’t looking for it you probably wouldn’t notice it. Did they take the measurement and then make the mark or vice versa? A Benchmark denoted a levelling point, hence the number, in feet, nearby, and the triangle marked the spot for triangulation. Are they one and the same place or was the triangulation in a different spot. Close by there was a spot that would have been perfect for a tripod and theodolite.
Dropping down from the Tor onto the Moor I set out to find the other two marks that are shown on the map as you head south-west towards the walled enclosure. Success was not to be mine. I needed to do a great deal more work on the position of the marks. The bracken hid many boulders and time had allowed moss and lichen to grow over a large number. I didn’t want to disturb too much so looked but could not find the two.
I did find other items of interest though. A possible burial cairn, complete with chamber. A partially finished grindstone, some way from the traditional grindstone fields and more markings that were different to the Ordnance Survey marks.
A few hours spent walking in the foot steps of surveyors and masons and perhaps Bronze Age man.
I like collecting things. Triangulation points are a favourite along with benchmarks that can be found along a walk or near to one.
There is something very satisfying about reaching a trig pillar, partly I guess because they invariably involve a walk up hill and a reward of sweeping views, weather permitting. There are 84 pillars within the Peak District National Park boundary and many more triangulation points and thousands more benchmarks.
Some are not shown on maps with the traditional blue triangle, the one at Hey Edge for instance, built but never used for triangulation, but was used for levelling, so does it not qualify for the blue triangle.
Some triangulation points are not even pillars. One of my walks takes in the Hunting Tower on the Chatsworth Estate, the triangulation point being the flagstaff. Another is the centre of the spire of All Saints Church in Bakewell.
With the advent of GPS the triangulation pillar network became largely redundant, but a few still do have a purpose. The pillar at Harland South, levelling bracket number 2998 is part of the Global Positioning Network and as such is protected by Ordnance Survey. A plate informs the visitor that any damage should be reported to the phone number.
Triangulation points always come in a minimum of three so a favoured walk of mine takes in the Hunting Tower at Chatsworth, the pillar at Birchen Edge along with the Three Ships and the pillar at Harland South, passing Hobs House, one of the first ancient monuments to have legal protection in the UK, on the way. Two pillars, one part of the Global Positioning System and one flagstaff on a hunting tower. Not bad for a day out.
Last year I started to collect all the Ordnance Survey triangulation points in the Peak District National Park boundary. I am about half way through now, although it was supposed to be finished within the year, but the days ran away with me.
There are 94 points if memory serves me correctly. The points are buildings, surface blocks, pins and the king of all tick list features, triangulation pillars.
I try to do a walk that includes 3 points, hence triangulation, its a bit of OCD within me that likes uniformity, it wouldn’t seem right doing four points.
Doing the research is fun, I didn’t know actual buildings could be points, but it makes sense. Bakewell church and the Hunting Tower at Chatsworth are two good examples. High with good lines of sight. I looked a bit weird in the Church with my GPS outstretched moving around one pace at a time, looking at my hand then looking up at the spire, and this was inside too.
Finding a surface block in thick undergrowth is very satisfying as is navigating to a pin. Some I have had to go back to as time has caught up with me before I have found them.
The best feeling is reaching a triangulation pillar. It generally involves an uphill slog, sometimes via a circuitous route, often with the pillar staying out of sight until the last few hundred meters. I think the hard work getting there is part of the joy I feel once I am at the spot. Then there is the view and searching for the, at least, other two that should be able to be seen in the distance.
Some of the pillars are a bright white, some have the lovely mottled concrete surface. Some have been adorned with plaques, some have graffiti. There are some that have been obliterated all together and some that lay forlorn away from their original site. Some hide in hedges, all pristine as the day they were made.
A summers day in a field, sat by a trig pillar that nestles in a hedgerow, eating my sandwiches while birds twitter on and the view looks all sky blue and green grass is one of the happiest ways to spend a few hours.