A journey through the mysteries of the caves

Have you ever been inside a cave or seen the inside of one in a photograph? As you may have noticed, both on the ceiling and on the floor there are some very peculiar formations.

These formations are known as stalagmites (floor) and stalactites (roof). Although they are phenomena of nature that take thousands of years to complete, you can recreate them at home with ingredients that you probably already have. Do you dare to learn through this experiment?

You will need the following materials:

✔ A rectangular container or kitchen paper
✔ 2 small glasses
✔ Sodium bicarbonate
✔ food coloring (optional)
✔ A piece of string or woolen thread
✔ 2 clipboards
✔ Hot water
✔ Spoon


Fill both glasses with very hot tap water. Then add several tablespoons of baking soda to each glass and stir with the spoon. Continue adding baking soda until no more dissolves (the mixture is supersaturated) and there is a layer of baking soda at the bottom of the glass. If you wish, you can add about 5 drops of food coloring in each glass. Place the glasses inside the rectangular container or on the kitchen paper.

Finally, create a U-shaped bridge between the two glasses. To do this, we will use a piece of wool thread. Tie each end of the woolen thread to a paper clip. Attach the ends to each glass, letting the string hang in a U-shape between them, but not touching the container or kitchen paper. Observe the string over the next few days to see crystals form along the string. Now, it’s time to ask yourself a lot of questions. What do you think will happen?


As you may have noticed, the wool absorbed the mixture and when the water evaporates, all that remains are the sodium bicarbonate crystals. Hanging crystals form when the mixture begins to drip from the wool and evaporate.

This experiment is a demonstration of what water does as it drips into caves. In nature, stalactites are cave ceiling formations created by falling water depositing minerals. Stalagmites, on the other hand, form on cave floors below trickling water, where minerals begin to accumulate.

While bicarbonate crystal formations grow fairly quickly and are made up of small crystals, it can take thousands of years for crystals to form in natural caves. Believe it or not, some caves contain single crystals over 35 feet long. Imagine the amount of time they took to form!