Discipline: Earth Science
Age Range: 10-14
Estimated Time: 20 minutes
What you need: Download the Weathering Scavenger Hunt activity sheet and you’ll need an area outdoors with rocks
Instructions:
Have you ever wondered what causes rocks to break?
In science, we have a special word for when rocks get broken down by nature. It is called weathering. Weathering is the natural process of breaking down rocks and minerals into tiny pieces of sediment.
Did you know that there can be other ways that weathering can break down rocks? They are called Freeze-thaw, water, and vegetation.
Can you guess how these three things break down rocks?
Freeze-thaw making rocks crack
Freeze-thaw is when water freezes and pushes against the rock as it expands making the rock crack. You might have seen something like this happen if you ever left a soda pop in the freezer. What happened to the can?
Water breaks down rocks, so they are round and smooth. Have you ever felt a smooth river rock? The force of sediment and the water hitting the rocks over long periods of time makes this happen.
Water breaking down rocks
Vegetation is a special word meaning plants. Can you think of a word that sounds similar to vegetation? Vegetable! Vegetation can break down rocks in two ways. One way is then plants grow and push against the rocks causing them to crack. Have you ever noticed that tree roots can creak driveways? Pretty strong, right! Plants can also produce a chemical that breaks down the rocks too.
Vegetation pushing against rocks to make them crack
Now that you know the three different ways weathering can break down rocks go outside and see if you can find:
1. One rock weathered by freeze-thaw.
2. One rock weathered by water.
3. One rock weathered by vegetation.
Helpful Hints: More than one type of weathering can break down a rock. You might see rocks that look like both water and vegetation have broken them down.
New Words:
Weathering: The breaking down of rocks and minerals into sediment.
Freeze-thaw: When water freezes and pushes against the rock making it crack.
Vegetation: Plant life.
Photo sources:
Freeze-thaw
Water
Vegetation