Home >> Science & Nature >> Rocks & Minerals

How to Create a Model of Stalactites & Stalagmites

It's hard not to marvel at the strange beauty you encounter when taking a tour through a system of caves. Those amazing columns and formations were slowly created over thousands of years by mineral-laden water as it seeped through the earth's surface, and the process is still, in most cases, continuing. The formations hanging from the ceiling are called stalactites and the shapes growing up from the ground are stalagmites. Remember which is which by associating the letter "t" in "stalactites" with "top" and the letter "g" in "stalagmites" with "ground."

Things You'll Need

Two glass jars
Cotton string or yarn
Two small nails
Epsom salts
Small plate
Water
Spoon

Instructions

- 1
  Fill the jars with water and stir in enough Epsom salts to make a saturated solution; the solution is saturated when the salts no longer dissolve, and a residue forms on the bottom of the jar. Place the jars on either side of the plate.
- 2
  Measure a piece of string that's sufficiently long enough to reach loosely from the bottom of one jar to the bottom of the other, and add a few extra inches for tying a nail to each end. Place the ends of the string in the jars and position them so that the string is sagging slightly where it hangs over the plate between them.
- 3
  Monitor your model every day and note the movement of the solution as it travels up and along the string. The salts will eventually build up in the lowest part of the string and begin forming a stalactite and, later on, a stalagmite.
- 4
  Continue the experiment until the stalactite and stalagmite form a pillar.

Rocks & Minerals