How stuff works: Breaking rock with sticks

Here’s how they broke large rocks before heavy machines or explosives were known:

Drill holes or cracks in the rock and fill them with water. At night the water freezes and expands. But since it freezes top-down it seals the hole and cannot overflow. Thus it exerts pressure on the rock until it breaks. Sounds reasonable, I can believe that.

Here’s how they supposedly did it in Egypt, where water does not freeze at night:

Again, drill holes or cracks in the rock. Then, drive a wooden stick into the hole and pour water over it. Then, […], the rock breaks.

Fill that in, please. How does it work?

I believe the wood expands when wet, causing additional pressure allowing the rock to crack.

But how does this create pressure? Even if additional volume is produced, wouldn’t it just push the water out?

There was a program on TV about this some months back: they said that Egyptians used harder rocks to abrade the softer rock. A very lengthy process. In the mining areas, there are still columns left when extraction was stopped because the piece cracked or broke or whatever.

It’s hella easier to break rocks without heavy machinery when you have the benefit of slaves. I mean, if you need a guy to bust your stones, you can’t go wrong with a Jew.

Wood expands across the width of the grain, not along its length. The tendency for the water to be absorbed into the structure (presumably through capillary action and surface tension) is quite considerable - if you think about the process in reverse, it would take a great deal of force to squeeze a piece of wet wood dry.

Without wishing to offend the earlier respondants, that sounds more like it. Thanks!

There is considerable archeological evidence that the Egyptians did not use slaves in building the pyramids. Additionally, most of the pyramids were actually built prior to the time the Jews were believed to have first appeared.

High temperature variation will readily crack large rocks or detach them from the mother rock. A whole bunch of both archaeological and ethnographical evidence for the use of fire to extract / break down lithic raw materials.

Moderator Warning

This kind of comment is inappropriate for GQ, or probably anywhere else on the SDMB aside from a MPSIMS thread titled “Post your lamest ethnic jokes here!”

Frankly, Argent, you seem to have such a tin ear about what is and is not an appropriate joke that you would be better off not even making the attempt.

Don’t do this again.

General Questions Moderator