Topographical survey

Topographical survey involves using a dumpy level, theodolite or electromagnetic distance measurer (EDM) to build up a contour survey of the surface of a site so that a logical plan can be made of what is usually a jumble of earthworks.

The equipment is all used slightly differently but they all have to be tied into a National Grid Reference either before or after the survey. A dumpy level and a theodolite need to have measurements taken along a grid set out on the ground whereas an EDM can work out how far away and in what direction the measuring staff is as long as it knows its own grid reference, which must be worked out from nearby prominent features.

Topographical surveys have been undertaken in Buckinghamshire, such as by the Chess Valley Archaeological and Historical Society in 1997 at the medieval farmstead at Bray's Wood, Amersham or by English Heritage in 2000 at Ivinghoe Beacon.