THE CHANGING PLANET

BACK TO BRYCE Let's take another trip back to Bryce Canyon and southern Utah. Are there any other ways that the forces of nature are wearing down the Earth's surface? On a previous page, you learned that ice can cause weathering in Bryce Canyon and other cold places. Wind may also cause weathering. Small particles of soil or sand, carried by the wind, can act like a sandblaster and break off tiny pieces of rock from larger rocks. Running water such as runoff, streams and rivers may also slowly wear away rocks and carry them to other places. Chemicals formed by decaying plants and rain water can break down rocks. Animals, by digging, burrowing, or making trails, reshape a Canyon's surface. Even plants cause weathering and erosion! Over many millions of years all of these things have changed the way that Bryce Canyon looks. Remember, weathering is nature's process of breaking rocks into smaller pieces. Erosion takes the weathered material from one place to another.

THINK ABOUT IT! Examine the list below. Place a "W" beside each word that represents an agent of weathering. Place an "E" beside the agents of erosion. If the term fits both categories, place both letters beside the word. When you are finished, highlight the box below to see how you did; Ice Water Plants Animals Wind Gravity All of the above can be responsible for weathering and erosion except gravity. Gravity cannot break rocks apart. It can only move them from one place to another.

YOU'RE THE SCIENTIST! MATERIALS: This is what you will need. As many different rock types as you can find to perform the experiments that you design Sandpaper Vinegar or lemon juice Water Freezer container PROCEDURE: This is what you will do. Use the materials above to design one or more experiments about weathering. Record a hypothesis for each experiment. Write down the steps you will follow for each experiment. Record observations for each experiment. Write down a conclusion for your experiments. Was your hypothesis correct?

DO IT! Study the pictures on this page. Do you think that the geologic features in them will change in your lifetime? Do you think that they will change significantly in a thousand years? Write a paper explaining your answer. Draw a picture of how you think the geological features in the pictures; looked a million years ago will look in a million years

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Revised March 1, 2002 by Kathleen Ochsenbein