Over four Saturdays in October and November 2009, a dedicated team of enthusiastic B.A.G members, at the request of Farningham Cricket Club, set about doing a resistivity survey of the whole cricket field. We were asked to do this by the grounds man Richard, to finally find the cause of the various lumps and bumps that appeared to form unusual patterns across the pitch, giving rise a number of theories about Roman roads and buried treasure!
The team was made up of: Pip, Martin, Steve, Janet, Sally, Clare,
Marian, Chris, Francine, Ron and our President Dave
The ground was roughly aligned north-south and we measured out 20 meter square grids starting in the north-westerly corner of the field, working our way eastwards. The surveys all went well, with each of us doing some laying out of grids, moving tapes, wandering off to explore the surroundings and of course walking the meter across the grid taking readings.
We managed five grids on each of the first and second days. The third day proved a bit tricky as the central cricket pitch and wickets were fenced off and being re-seeded, so we were not allowed on it. We did two 20x20m grids and one 35x20m.
The last day we did four 20x20m grids but only found out as we laid out the last grid, that we were not quite square to the previous three rows of grids. We managed to work out how much we were out so that I could allow for it when I put the data together.
My involvement in the project was partly due to my interest in maps and my use of computers in interpreting the data from the resistivity meter.
I gathered together all the maps I could find and we were provided with a selection of aerial photograph dating from the end of World War 2 up to 1996. These were scanned into the computer and electronically placed one on top
of the other exactly over the cricket club site.
My oldest map was from 1797 and is too inaccurate to be of much use but I have one from 1840, which I used as my base.
Here we see four of the layers, each one will fit exactly over the other
1840 1996 Aerial photo
Google Earth image Modern Ordinance Survey
After all the grids were surveyed and the data collected, each grid could be plotted out on an aerial photo (my favourite being provided by Google Earth)
We started with our 00 point in line with a long white fence, so it was easy to locate on the aerial photo and place each image very accurately. Once all the grid images were placed, I could then enhance them to bring out better detail. The most useful enhancement feature is to apply an embossing effect.
This really gives an impression of contours on the ground but you have to remember that this does not show true contours, it only enhances rough and smooth areas.
The final results are shown below and are now being analysed before any conclusions are made.
Above: the unchanged images from each of the 17 grids
After the embossing effect was added