Ground penetrating radar finds a grave as a disturbance in the soil, a shape at a depth, and a churchyard survey maps every one against the burial register so the parish knows where it can still dig. This yard has one shape the register cannot account for, at grave depth, the size of an adult, and on each of four surveys it has been somewhere else.
I survey churchyards, mostly for parishes that want to know where there is still room.
How the survey works.
The radar goes over the ground on a cart, in lines a half metre apart, sending pulses down and timing the returns. Disturbed soil returns differently from undisturbed, and a grave shows as a shape of the right size at the right depth. I map the shapes and lay the map over the plan and the register, and every shape is matched to a burial, or noted as unrecorded, which is common, because registers have gaps.
An unrecorded grave is where it is. The ground does not move.
One yard, a small country church with a register back to the seventeen hundreds, has one unrecorded shape.
I have surveyed that yard four times over six years, for different reasons, and the shape has been in a different place on every survey.
Adult sized, at about five feet, with the returns of a grave that is old but not ancient, in the part of the yard that was in use in the nineteenth century.
First survey, north of the path. Second, east of the yew. Third, by the wall. Fourth, back near the path but not where it was the first time.
Every other shape in that yard is where it was on every survey, to the half metre, against the same plan.
What has been checked.
The equipment. Different radar units on two of the surveys, calibrated on a test site with buried targets of known position, and they found the targets where they were.
The processing. I have reprocessed all four surveys from the raw data, blind, and the shape is where the maps say.
The ground. On the second survey I put a probe down at the shape's position. Disturbed soil, the texture of a grave fill, at five feet. On the third survey I probed the second position again. Undisturbed clay, packed, the way the yard is where nobody has dug.
The disturbed soil of that grave was north of the path in year one, and in year three the soil north of the path had never been dug.
The register.
I have gone through it for a burial with no plot. There is one, in 1861, a woman, with a note in the margin in the rector's hand that says buried by night, position not marked, at the family's request, and nothing else.
Nobody at the church knows the story. The family name is not in the parish now.
What is done about it.
My report to the parish shows the yard with every grave matched and one unrecorded burial marked at its most recent position, with a note that the position is uncertain, which is the wording I use for a shape that is hard to resolve.
It is not hard to resolve. It is perfectly clear on every survey. It is in a different place.
What I do.
I survey.
The one thing I have changed is that at that yard I do the survey lines alone, and I do not have an assistant walk the grid ahead of the cart to mark it out, which is how I usually work.
The reason is the fourth survey, when my assistant was walking the grid and I was watching the screen, and the shape came up on the screen where she was standing, under her feet, at five feet, when it had not been there on the previous line, half a metre away, a minute before, and she stopped, and said she had felt the ground give a little, and I said it was the mole runs, and it was not, and I had her go and sit in the van.