ABSTRACT
ELECTROMAGNETIC SURVEYS Non-contacting terrain conductivity meter creates an elec tromagnetic field in the ground and measures field distor tion some metres away; low-cost equipment, simple to use, similar in principle to large metal detector. Measures mean conductivity in a hemisphere of ground reaching to depths of 6-30 m. Can be continuous reading, two-man operation. High conductivity of clay, basalt and water, contrasts low conductivity of sand and limestone. Can use to map shallow lateral changes: clay-filled fissure zones, filled sinkholes, rockhead steps, alluvial channel fills, highly-permeability fracture zones.
