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MHG55391 - Fundamental bench mark, Lairg

Summary

Lairg fundamental bench mark (FBM), part of the Ordnance Survey's framework of permanent height markers.

Type and Period (1)

Protected Status

Full Description

NC 5723 0764 At a height of 120.73m, the position of the Lairg FBM, built in 1950, is given as 6m NE of road and 37m NW of a gate.
Information from Mark Greaves (OS) 23 November 2011

An underground concrete chamber containing two permanent height markers, and marked at ground level by a granite pillar about a foot high. The two primary reference points lie underground and consist of a gun metal bolt and polished flint both set into fine granolithic concrete and protected by iron covers. A gun metal bolt on the granite pillar provides a third reference point.
There are currently 194 fundamental bench marks across the UK mainland (22 in Highland) which were built between 1911 and the early 1950s. They are established along the Geodetic lines of levels at approximately 30 mile intervals. Lairg FBM records an altitude of 120.73 m AOD. <1>

The Ordnance Survey Geodesy Team have asked to be notified of any development proposals which meet the following criteria:
1) If an FBM falls inside the boundary, or within 30m of the boundary of a proposed development upon completion.
2) If an FBM falls inside the boundary, or within 30m of the boundary of the "construction area" or any other temporary area of a proposed development.
They also wish to be notified in any other case where an FBM may be at risk of disturbance. Should an FBM be threatened they will create a new one nearby at their own expense before the threatened one is lost. This is to ensure the continuing integrity of this vital network. <2>

Sources/Archives (2)

Map

Location

Grid reference	Centred NC 5722 0764 (60m by 60m) (2 map features)
Map sheet	NC50NE
Geographical Area	SUTHERLAND
Civil Parish	LAIRG

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External Links (2)