Observation Questions:

1. What happened to the solution in the containers? Some water soaked into the yarn and dripped onto the wax paper. While some of the water evaporated leaving slat crystals on the side of the glass containers.
2. How is this experiment similar to the formation of stalactites in caves? Stalactites are a type of dripstone that forms from the ceiling of caves. Groundwater travels through cracks and joints in the sediments and rocks above the cave. When Carbon dioxide escapes into the air of the cave calcium carbonate is deposited around the drop of water. A limestone icicle is formed drop by drop. In this lab as the water soaks into the suspended piece of yarn it is traveling into the air in the cave. As the water evaporates into the air a residue of salt crystals are left behind. The crystals form icicle shapes hanging from the yarn.
3. How is this experiment similar to the formation of stalagmites in caverns? Stalagmites are dripstones formed on the floor of a cave. Groundwater that falls to the cave floor deposits a rounded mound of calcium carbonate that accumulates upward. The water that drips down on the wax paper evaporated to leave a mound of salt crystals that resemble a stalagmite.
4. Explain how columns can be formed in side caverns. Columns are formed when a stalactite forms downward from a cavern ceiling to meet a stalagmite forming on the cave floor. Students may from a column if given enough time for the crystals to join together.
5. In nature do speleothems form above, below or in the zone of saturation? Support your answer with a labeled diagram. Although most caves that have speleothems are formed at or below the water table. The cave is formed in the zone of saturation. Slightly acidic water like rain water that contains carbonic acid dissolves away rock creating an underground cave. In nature speleothems form in air so the cave has to be in the zone of aeration in order for dripstones to grow. If the cave was still in the zone of saturation any calcium carbonate would be carried away with the percolating water to the sea. It could not be deposited on the cave ceiling and floor. The salt crystals in our lab were formed along the yarn and the sides of the container that were in the air not in the water.

Follow-up:

See if you can create any other cave formations such as soda straws or cave pearls
Try other solutions like Borax or Laundry soda or Alum observe the crystal formations

Video Support: National Geographic- Mysteries Underground