Cave in a Cup Demonstration

Hi guys, today I wanted to share with you a fun simple demonstration about how caves are formed. 

Caves are typically formed by water. When it rains, the water oozes into cracks found in softer types of rock (limestone). As time goes by, the liquid slowly dissolves the nearby rock and wears it away. This causes the cracks to gradually widen in caverns. As the water level drops, caves and passages that we can explore are left.  

Material

1. Clear container or cup

2. Sugar cubes

3. playdough

4. dropper

5. toothpick

Instructions

Form a wall of sugar cubes on the side of your container. Roll out the playdough and cover the sugar cubes. Seal the sides by squishing the playdough on the edges. Make holes on the top of the playdough using your toothpick. Drop some water on the playdough and observe what happens. If the water is not getting in make your holes bigger. The holes represent the cracks in the rocks. 

This demonstration will show your child how a cave is formed. As the water seeps into the holes and reaches the sugar cubes, the sugar cubes start to dissolve. This is similar to what happens in a cave. As water gets into the cracks it slowly erodes the soft limestone rock. In a cave this takes a long time to happen. Once the water drains away you have an empty space and a cave has been formed. You can make a hole at the bottom of your cup and do it over a sink or bowl. Once the water drains away you will be left with your cave in a cup.