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Three people were involved each time, operating the meter and organising the measurement of the squares. The probes were inesrted in each metre square. In the summer of 2000 the group asked Peter Cott, who has a resistivity meter, to come to Thriplow and survey an interesting area in the field next to the school.

A resistivity meter measures changes in electrical resistance in the soil by passing an electrical current between probes set in the ground.  The resistance to the passage of the current is measured and then translated by a computer into a plot as shown below.  It is one way of finding hidden structures under the ground.
  Rounded Rectangular Callout: Touch the picture to find out what the squares mean.
Plot of the resistivity survey of part of the school field and adjacent meadow. Each square recorded on the plot is where a reading has been taken. The school building is marked just on the right. A is pointing towards an area of high resistance (dark coloured) enclosed by a reverse "L" shaped area of low resistance. (light coloured)  This follows the line of a shallow ditch.

 

B is pointing towards another area of high resistance abutting a low resistance area.  This may indicate the straight edge of a paved area under the ground.

Links to more details
Documentary evidence Plane table surveying
Place name analysis Resistivity surveying
Aerial photography analysis Dowsing and pond dipping
Geology Courses and visits
Soil sampling Community links
Metal detecting Acknowledgements