OS Benchmarks in the Peak District

Ordnance Survey map of 1882 showing Woodlands Valley in Peak District National Park
Ordnance Survey map of 1882 showing Woodlands Valley
REPRODUCED WITH THE PERMISSION OF THE NATIONAL LIBRARY OF SCOTLAND HTTP://MAPS.NLS.UK/INDEX.HTML

Old maps are a great way to follow the history of the landscape. Ordnance Survey have been surveying the Peak, then the Peak District National Park for hundreds of years. The maps we know today started life back in the mid 1800’s when teams of surveyors were sent out across the country to accurately measure the land, the buildings, boundaries, rivers and roads.

To accurately measure height the surveyors took a datum of the mean tide height, firstly from Liverpool and in later years from Newlyn. Having one fixed point, a benchmark, all other measuremenst could be taken as the surveyors worked their way across the country. Each time they measured the height of a particular spot they would mark the position with a cut mark of an arrow pointing up to a horizontal line, the benchmark.

Ordnance Survey map of Hag Farm showing benchmark position
Ordnance Survey map of Hag Farm showing benchmark position
REPRODUCED WITH THE PERMISSION OF THE NATIONAL LIBRARY OF SCOTLAND HTTP://MAPS.NLS.UK/INDEX.HTML

Benchmarks were placed on solid stone, stone buildings, stone gate posts, and walls, fixed items or structures that were unlikely to be moved. In total there are in excess of half a million benchmarks in the country, with over six thousand as the flush brackets most commonly seen on Ordnance Survey triangulation pillars.

So that still leaves a lot to be identified and spotted when out walking. The benchmarks are a good navigational challenge, and an excellent piece of detective work. Looking at old maps, such as the ones above, the benchmarks can be identified as small arrow heads along with a number in feet. Old boundary walls, buildings and gate posts are the easiest to find. Harder are the ones placed on boulders in the middle of a moor for instance. Judging the grid reference from an old map can be a challenge, but when you have got it right and you arrive at a benchmark in the middle of nowhere it is a great feeling of achievement.

The benchmark shown in the map from 1882 above shows a position and height of 872.4 feet and is at the junction of two tracks. Today one of the track has a gate across it and the left hand gate post has the benchmark beautifully cut a foot or so above ground level.

Today Hag Farm is called Hagg Farm on the current OS map, yet another interesting historical feature of old maps. In fact all the names on the 1882 map starting or ending in “Hag” now have an extra “g” added and this seems to have happened between 1880 and 1897 when the next OS revision of the map took place.

Ordnance Survey map of Woodlands Valley 1897. Peak District National Park
Ordnance Survey map of Woodlands Valley 1897
REPRODUCED WITH THE PERMISSION OF THE NATIONAL LIBRARY OF SCOTLAND HTTP://MAPS.NLS.UK/INDEX.HTML

Perhaps the names were changed by the surveyor or a greater understanding of local names and spellings was achieved for greater accuracy. Whatever the reasons, the Ordnance Survey maps for a fascinating and beautiful historical document.

All of the items mentioned in the post can be found on or near Walks No.13 of Dark Peak Walks published by Cicerone Press.

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Dark Peak Walks Book by Paul Besley, published by Cicerone Press. 40 walks in the Dark Peak with detailed route descriptions, maps, photos and points of interest.
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Author: Paul Besley

Writer I have spent most of my life escaping into the Peak District National Park, I have grown to love the solitude it can bring. I also have an interest in the growing field of psychogeography particularly, in post-industrial landscapes. I am the author of Dark Peak Walks published by Cicerone Press. I am also studying Creative Writing at Sheffield Hallam University.

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