Geophysical surveying

Map of the Eddleston site showing the geophysical 'survey lines'

Three different types of near-surface geophysical surveys were carried out at the Eddleston site to help explore the shallow geology of the site.

The techniques used were:

electromagnetic induction (EM, also referred to as ground conductivity mapping)
2D electrical resistivity tomography (ERT) and
ground penetrating radar (GPR)

An example ground conductivity map for the Eddleston site

An example of a ground conductivity map

This combination of electrical and electromagnetic (EM) techniques is a common application in investigations of shallow Quaternary deposits, and has been used successfully in a variety of recent BGS projects.

The geophysical results were used to develop the 3D geological model and to help decide where to site the floodplain boreholes.

Cross sections

The image below is an example of an ERT (electrical resistivity tomography) geophysical cross section across the floodplain/valley floor and the adjacent hill slope.