WEATHERING AND EROSION

This lab is an introduction to the concepts of weathering and erosion. Students will simulate the processes of weathering and erosion.

Materials

Chalk

Lemon juice

Paper plates

Invitation

  1. How many of you have been to the beach? Did the beach have any sand on it? Where do you think this sand might have come from? How do you think sand forms?
  1. How about pebbles? How do you think they form? Has anyone ever seen a boulder? Do you think they formed the same way as pebbles and sand?
  1. Where do all these things come from? What are they? Broken up pieces of larger rocks. These are called sediments.
  1. But rocks are pretty hard. How do you think they get broken up? What are some ideas? Breaking up rocks is called weathering them. We are going to work on breaking up rocks today. We are going to explore the process of weathering.

Exploration / Concept Introduction

I am going to give each group a piece of chalk and a paper plate. The chalk will be our rock today. In a minute, I want you to weather, or break up, this rock. How will you do it? Does anyone want to share?

Ok—break up your chalk.

Ok, you broke up your chalk and make sediments. So by banging on it you were physically weathering the rock. Physically weathering involves something physically touching the rock.

  1. What are some things in nature that could physically weather rocks? Wind, water, ice (glaciers)
  1. Can you think of any places where you can see how ______physically weathers rocks? Wind—arches national monument, Water—grand canyon (any river), Ice—Yosemite, Niagara Falls

Now we are going to put acid on our rocks and see what happens. Pour the lemon juice on your chalk. What happened? It dissolved.

Acid can slowly cause rocks to dissolve. This is called chemical weathering. It doesn’t just break part of the rock physically, it dissolves it. Rainwater is slightly acidic and can cause rocks to dissolve. Then the chemical parts of the rock, or ions, are carried away by water.

Application

  1. Living in FL, can you think of any feature caused by chemical weathering? Discuss sinkholes.

2