River Rocks and Campfires?

Question

I just got back from a camping trip and saw a lot of people making campfire rings using river rocks (taking rocks out of the river and using them to make a circle around a campfire pit).

I seem to remember somewhere that this was a bad idea but I have no idea as to where I heard this (probably on some sitcom TV show). I seem to remember something like this:

If you use river rocks then there can be minute small amounts of water dissolved into the rocks in cracks or minerals etc. When the fire heats these rocks they can crack or in the worst case shatter and fling out fragments. Needless to say I thought this was something you shouldn't do but I have no idea where in my childhood I heard this.

Can anyone let me know if using river rocks around a campfire is dangerous in any way?

Thanks

Answer 1

what about bigfoot???

Answer 2

Since no one with any sense is going to sit that close to the fire, the snap, crackle, pops from that aren't going to cause much harm.

It is a safe way to keep the fire contained, and makes it easier to lay a "grill' across the rocks.

It would be nice to have had you guys replace to the near area where you got the rocks, but if you left the area cleaner than when you got there that's okay too.

Answer 3

Any rock, whether it is a river rock or otherwise, can explode if heated very vigorously. The smaller the rock, the less risk of that explosion. So that when we have pebbles they rarely explode.

If you toss water on any rock that is heated, you risk having that rock explode as its outer surface contracts.

Water inside the rock will not produce the force of explosion that expansion of the outer layer does, and it will be far less than sudden cooling of outside layers of rock.

Water in rock does cause freezing rock to break, but not explode.