Is there any type of device that can locate a buried metal box, even if a metal detector can't find it?

(Other than a very long pointy stick, I mean.)

Long, long ago, when I was in fifth grade, we buried a time capsule in front of the school. I don’t remember what we put into it, but all the classes participated. I think the plan was that we’d dig it up after 50 years, but now no one can find it.

We know generally where it is, and some of us remember where it’s supposed to be, but they couldn’t find it even with a metal detector. I do know that metal detectors work poorly or not at all some types of metal, so that’s one possibility. Or is there any kind of metal that would simply disintegrate over 50 years?

Is there any other kind of dev8ce that could be tried? I wouldn’t be able to try anything myself because I don’t live in the area anymore, but I can pass any suggestions on to our group FB page.

Archeologists use ground penetrating radar to look for features in prospective dig sites. Not sure whether or not the resolution is sufficient to be able to distinguish a single metal box though, and it’s not the sort of thing you can pick up at a hobby store.

A ground penetrating radar may identify a dense cube if it was buried in contrasting material, but if it was buried in a layer of building rubble may be harder to discern from background.

Metal is best detected with a magnetometer. This measures variations in the local expression of the Earth’s magnetic field, and a big metal box is hopefully going to make a large disturbance in the Force.

Some utility location devices work off this principal, but possibly a local university archaeology department or archaeological consultancy will be your best bet.

Yeah. I would be looking at getting a geologically useful magnetometer. A Cesium vapour magnetometer in a portable setup is a common device used for ground based surveys. These are very very sensitive. Not quite SQUID sensitive, but they can detect pretty ridiculously small wobbles in the magnetic field.

If you had a steel case, and it has substantially rusted, a conventional metal detector is not going to see it, but the magnetometer may still pick up a glitch. So, in additional to a local archaeology department, talk to the geologists. In some places it is common for geo students to spend days on field trips making a bit of money just walking back and forth with one of these on their back.

Or, somebody fixing sewer lines dug it up years ago.
Sorry, but it may well be gone.

Do you know if the person operating the metal detector was experienced at it? There’s a bit of art to metal detecting and knowing what to listen to. If the person was inexperienced, you might want to put out feelers in your community to see if you can find someone who has done it a lot. Craigslist might be a good place. A while back I needed to find a metal survey rod on my property. I put a post on CL and had a ton of responses from people wanting to help me find it. I guess they enjoy their hobby and are eager to help out.

Yeah, I was thinking they should see if there are any maintenance records to check for that sort of thing. Find out if there were any construction or major landscaping projects between whenever you buried it and now.

Was there a school newspaper back then? If so (and the school still has copies) they may have posted an article showing it being buried which you could check. Likewise if there was a small rural newspaper–they used to do that type of coverage.

In 1957, they buried a Plymouth Belvedere near the courthouse in Tulsa, OK, as a time capsule. 50 years later, they dug it up. The car was buried in a concrete tomb to protect it, so people were expecting to see a car that would be drivable, maybe with a bit of work. Instead the car came up as a completely rusted and worthless hunk of junk.

Given that your metal box was probably steel and did not have any protection from water and rusting, there may not be much, if anything, left of it.

Five decades are sometimes unkind to metal things.

https://axleaddict.com/cars/MissBelvedere

Says Wikipedia:

Reflecting the Cold War tensions endemic in late 1950s America, the enclosure – built of poured in place concrete and sprayed with pneumatically applied gunite – was advertised as having been built to withstand a nuclear attack.[7][8] However, the vault was breached by long term water intrusion, that submerged the entire vehicle, causing significant cosmetic and structural damage.[9][10][11]

I cemeteries, they don’t want to dig and hit vaults that may have shifted into the next plot. So they push a long steel probe into the ground. If the OP has some fairly close idea of the original burial this may work.

Or, if the box has rusted enough, the probe might just push right through the rust, with only about the same resistance as the surrounding soil.