Bolt & Block Riddle

[mcross]

A teacher of mine once had a large cubical block of wood (10" x 10" x 10") with a notch -- four inches long and spanning its width -- cut into the top it. A hole had been drilled from the inside of the notch to the outside of the block. Through that hole ran an eight inch bolt. The top of the bolt was on the inside of the notch. It therefore could not be removed. It could, however, move freely back and forth within the hole.
I was told that this was not a trick -- that the bolt and the wood were true -- and that it could be explained logically. But to this day I have been unable to do so. Please help.

[MatydaLover]

Maybe the bolt was used to cut the hole?

[dustypuss]

soak the block of wood

[Tim123]

My guess would be that the head of the bolt can be unscrewed from the shaft.

[wildwood]

If you mean that the bolt and wood were true to be that the block is one piece of wood and not joined, and the bolt is as one would expect and not a tricky one, I would guess that the bolt is one that was used to hold a gate to a youngish tree. Over the years the trunk has grown around the head of the bolt and upon felling it some smart cookie thought this would make a great mind-bender and cut and shaped the block with the bolt so in place.

[chakka35]

A brilliant answer, wildwood. I'm sure that's it.

It reminds me of the gag that results in a fully-grown apple inside a milk-bottle, produced by tying the bottle to a branch of the apple tree so that it encloses a very small apple, which then grows inside the bottle.