Ordnance Survey surveyor marks

Lots of discussion on social media this weekend about Ordnance Survey marks on the gritstone of the Dark Peak in the Peak District. A topic that fascinates me with every walk including a foray into the wilderness to try to find some elusive mark made more than a century and a half ago.

Top left is a benchmark used to establish height at a point on the footpath to Stanage End from Moscar.

Below that is a benchmark used to mark a survey position on Higger Tor.

Top right is a really interesting one. An arrow below a square box with a dot in the middle. This denotes a survey height taken from the ground and not estimated. On modern maps today these are denoted as a black dot with a height number as opposed to an orange dot which denotes a measurement taken from the air.

Bottom left is a lovely levelling bolt, indicating a survey position near Laddow Rocks.

Bottom right two survey marks, one for levelling and one for triangulation found on Back Tor on Derwent Edge. On the left hand mark is a benchmark made by Lieut Barlow RE when he carried out the triangulation in 185. The right hand mark denotes a spot height taken in 1854 by Capt Kerr RE to establish the contour lines.

All heights back then used the Liverpool datum and approximate average of the sea height there. Nowadays the OS maps use the Newlyn datum taken from the tidal measuring station in Newlyn Harbour, Cornwall.

 

Gritstone Graffiti

It pays to keep your eyes open on a walk in the Dark Peak. It is also an advantage to look around at the gritstone that forms this wonderful landscape, because you might just spot some graffiti from another age.

Centuries ago people signified their claim on the land by making marks in the rock. These would often be used to signify boundaries and ownership. Beating the bounds, an annual perambulation, a word that means to traverse to inspect, meant a walk across the moors to check the marks were still there. Parish boundaries were a favourite as were boundaries where two estates met.

Some marks were simple crosses, such as the one on Hathersage Moor, made in the 19th century and which lies between the Sheepfold and Higger Tor. Others combined initials or motifs, such as the ‘T’ and ‘E’ at Back Tor on Derwent Edge. This one also sits beside and early surveyors mark made by the Ordnance Survey.

 

Trigpoint Walks 11

SK 1770 9697 Outer Edge 541m
SK 1770 9697 Outer Edge 541m

The classic walks of the Dark Peak offer the walker enjoyment of the highest order whatever the weather, come rain, snow or sunshine. The degree of isolation especially in winter when on a featureless high moorland deep in snow that is invariably being driven hard into the face by an unremitting wind, is a character building experience best savoured in warm surroundings with a hot mug of tea. The walker having endured such a day will quite rightly have earned the soft green hills of the White Peak the following spring.

The walk along the three triangulation pillars that look out over the Upper Derwent Valley is one of the great edge walks of The Peak District. It is not a long walk so there is plenty of time to stand and stare, or, better still find a vantage point and sit and watch, there will be much to view and learn.

I started from The Kings Tree at the end of the public road that winds its way up the valleys western side. A track leads across the young Derwent river via the Slippery Stones bridge, transplanted from the sunken Derwent Village, and heads off up the valley following the river. Above can be seen the edges that fringe the valley and it is to one of these that a shooting track climbs up from the river towards Crow Stones Edge and then onto the first trig at Outer Edge.

The views from the triangulation pillar are magnificent. Bleaklow, Kinder, The Great Ridge, Bamford Edge, West and North Yorkshire, all are there to be seen and no doubt on a crystal clear day well beyond that as well.

SK 1891 9569 Margery 546
SK 1891 9569 Margery 546m

The next triangulation pillar, Margery is in line with the valley and in a dry season is a pleasant walk, in wet and continuous rain it is a completely different matter. This is peat grough country, dark, thick, oozing, leg sucking. There is no avoiding it, so you might as well be prepared. Gaiters are a must as are tight laces to save lost boots. You can skirt some groughs but a strange and probably natural mathematical formula means that you can never ever escape the final ignominy of flailing about in a childish fashion whilst trying to look as though you are in control. It is also a natural law that having seen no one all day, as soon as you become stuck a ramblers group will appear out of nowhere, to ask if you need help, to which the answer is of course a firm NO.

From Margery I chose a little bit of a nav exercise, taking a bearing from Featherbed Moss to the shooting track of Dukes Road means a yomp across moorland, navigating between the wetter marsh areas to gain the track across Cartledge Bents. Near by is an old cross possibly used as a marker to the Grange at Abbey Clough nearby and well worth a visit.

SK 1976 9099 Back Tor 538
SK 1976 9099 Back Tor 538m

The slabbed track for Back Tor which can be seen on the skyline, threads through peat and bog, so at least the feet keep dry. I’m not sure about these paths, I agree they do reduce erosion and something had to be done, but they are sore on the feet, so I was glad on reaching Back Tor, to climb up to the trig, remove my boots and sit back and relax.

The vista really is superb, I was glad I had brought some binoculars so that I could watch the birds and hares and pick out favourite places on the horizon. After half an hours rest I set off down to Fairholmes visitor centre via moor, woodland and track, a great days walking whatever the weather.