The Mystery of the Moving Tombstone
Dutch police experts gather around a TV screen. They are watching footage from a hidden camera that was positioned to monitor a supposed case of vandalism at the graveyard of Aaslum, a little village of 160 people in the Dutch province of Fryslân.
In February 2009 the family of a recently buried man found his tombstone moved aside. After this occurred three more times, they called the police to find out who was disturbing their relative’s resting place. The police decided to place a hidden camera in front of the burial spot, and the resulting footage amazed onlookers.
A Chilling Mystery
“[It’s] Absurd, [and] it really gave me the creeps,” Anna Van der Meer, spokesperson for the Fryslân police, told the media. “When I saw the video I was flabbergasted. You can see the stone slide aside, almost falling to the floor. Then it comes to a halt against another gravestone of an adjacent grave, leaving the tomb open. How is that possible? I don’t know, the lid weighs around 400 kilos. Furthermore, in the video you can clearly see that the stone is standing still then unexpectedly, in the blink of an eye, it slides aside over a distance of about a yard. I have never seen anything like this in my whole career. We have no possible explanation.”
This poses quite a challenge for a mystery detective. Since I was planning a lecture tour of northern Europe, I called on my good friends at the Stitching Skepsis, the Netherlands’ group of skeptics. Jan Willem Nienhuys, secretary of the group, told me that no one in Aaslum was really afraid or concerned about what had happened, not even the priest of the church where the graveyard was located.
Since I was going to be in the Netherlands soon, I was hoping to witness the sliding of the stone firsthand, but Jan Willem explained to me that the stonecutter had taken the lid back in order to roughen the bottom part. He later secured it in place with pegs and cement, preventing any further movement. From that moment, the phenomenon stopped.
I was then able to count on the help of another good friend from the Stitching Skepsis, Gert Jan van’t Land, who got in touch with the police investigators. Unfortunately, the police refused to make available their files or any other formal information about the investigation because of the Dutch Law on the Protection of Police Information. However, Inge Oevering of the Netherlands Forensic Institute told Gert Jan, contrary to what newspapers had reported, that they did not conduct any investigation into the tombstone or the tape made on the graveyard. The Dutch “CSI-investigators” therefore could not provide any insight or information on the case. Gert Jan was also able to ascertain that Paul Andriessen, a Dutch geology professor incorrectly cited in the national newspapers as having studied the videotape, never saw the recording of the moving tombstone. He had only received a telephone call from a journalist who was interested in his opinion about the case.
A Freezing Solution
What is the most likely explanation for this unusual phenomenon? Some ghoul or ghost? According to the police officers who watched the video, the tape shows only a straight downward movement of the tombstone along the longitudinal axis of the grave and no upward movement of the tombstone, as had been reported in some media. Also, the movement occurred in the afternoon, and the tape shows sunny conditions and some melting snow or ice on the tombstone.
If the police officers in Fryslân gave a correct account of what was on the tape, the opinion of Gert Jan, who is preparing a detailed report on this event, is that the most likely explanation is unusual but not unlikely. The movement was almost certainly caused by water, under the right meteorological circumstances, entering into the crevice between the tombstone and the rectangular stone framework supporting the tombstone.
Several ingredients were needed to make the tombstone move in a straight slide along its longitudinal axis. The fact that the tombstone did not lie completely flat but at a slight angle was a prerequisite for movement by the force of gravity. The very smooth surface of both tombstone and supporting stone was the second ingredient in making the slide possible.
But the final solution lies in the fact that, as church sexton Tjerk Smits explained, every time the tombstone moved, the meteorological conditions were always the same: a cold night with temperatures below freezing, a bit of snow or ice on the tombstone, and sunny weather in the afternoon.
This all leads to the following scenario, as explained by Gert Jan:
Water from rain or melting snow entered the crevice between the tombstone and the supporting piece of granite; low temperatures formed a small layer of ice in the crevice. Since ice needs more space than water, the contact between the tombstone and the supporting pieces of granite probably diminished, [and] more and more the tombstone came to rest on a small layer of ice. The power of expansion of freezing water is considerable—in fact it was used in ancient quarries to split stones. The ice could very well have formed a bridge between the tombstone and the supporting pieces of granite keeping the tombstone in place. The afternoon sun probably heated the black tombstone, and the ice in the crevice melted. As more and more ice melted, the friction between the stones became less and less until the force of gravity won and the tombstone started to move. After [the tombstone] started to move (it “yielded”), downward movement continued until it was halted by an adjacent gravestone. Continuing movement after a sudden start is a normal phenomenon. It is well known in mechanics that friction between moving parts is less than friction between parts that are not moving. It can be seen in avalanches: after movement starts, it continues.
The tombstone had been constructed in October 2008. Since then, it appears it was just waiting for the right circumstances that would make movement possible.
Thanks to Gert Jan van’t Land, Jan Willem Nienhuys, and all my friends at the Stitching Skepsis for their kind help and assistance.