Have you ever visited a cave with all those cool “icicles”? They’re called stalactites and stalagmites, and they’re formed by water slowly dripping from the ceiling. The water has dissolved minerals in it, and little by little, those minerals stick to each other and “grow.”
Of course, the ones you see in the caves take thousands of years to grow, but here’s an experiment where you can make your own in just a few days!
What you Need
- two canning-sized jars
- Epsom salts
- food coloring (optional)
- wool string
- two washers or rocks (for weights)
- a plate
What you do:
- Fill your jars up with warm water and start mixing in Epsom salts until no more will dissolve. You can add food coloring to the water if you’d like.
- Cut a piece of string that’s long enough to hang between the jars, yet long enough to stay in the water on each end.
- Wet the string and tie a washer to each end, then drop one into each of the jars.
- Place a plate between the two jars, with the string hanging in a U-shape over the plate, then put it in a warm place where it won’t be disturbed for a week or so.
- Check your experiment at least once a day to check on your stalactites and stalagmites. They should start growing in the first few days.
A Quick Way to Remember
There are a couple of ways to keep your stalactites and stalagmites apart in your head. Remember that stalactites have to hold on tight to the top of the cave, and stalagmites have to be mighty strong to stand tall on the cave floor!
The other easy way is to remember that stalactites with a “C” grow from the ceiling, and stalagmites with a “G” grow up from the ground!