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18 September 2014
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History of a Landscape: Thriplow

By Dr Alan Crosby and Shirley Wittering
The true landscape revealed

Image of the plane table used assess the gradients
Assessing the gradients with a plane table 
  • Measuring the gradients and inclines of the landscape precisely
  • Finding out how to use a plane table and a resistivity meter

There are other ways to gather data on the precise measurements, gradients and location of the distinctive mounds of Thriplow, and the group sought expert advice. They asked Steve Kemp of the Archaeology Field Unit of the County Council to show them how to use a plane table to survey Godson's Close and Squirrel's Grove (names dating from 1279), two of the fields with interesting humps and bumps.

'... we persuaded the vicar to take us up the church tower.'

A 'plane table' is used to map the area accurately and uses a scale to plot areas which are then drawn on paper using long and short lines to show the steepness of the land. It's sometimes the most basic of equipment which yields the most exciting results!

In the summer of 2000, we persuaded Peter Cott, who had a resistivity meter, to come and survey for us. A 'resistivity meter' measures changes in electrical resistance in the soil. This is translated by a computer into a plot. It is one way of finding hidden structures under the ground. While this was going on Jim and I covered the same ground using dowsing rods. The results were similar but not exact.

In order to get a different perspective on the humps, we persuaded the vicar to take us up the church tower. This is built on the highest land in the parish, with a breathtaking view over the surrounding countryside.

We took pictures of the school field we had been surveying and compared the results. We also 'aged' the hedges by walking the lanes and counting tree species in the hedges. The theory is that that counted over a 100-metre length of hedge, the total number of species represents the number of centuries. The greatest number we got was six, representing the six centuries of the hedges' existence.

We continued to attend lectures, seminars and day schools, and met every fortnight to exchange information and ideas. We also visited other historical sites.

Published: 2005-03-03

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