Changing the Earth: Weathering

Lesson Plan - Get It!

Audio:

There are many different types of weather.

• What types of weather occur in your area?

Weather affects the earth in many ways. Rain, snow, heavy winds, cold temperatures, and hot temperatures all change the physical appearance of the earth through the process of weathering. You will learn about different ways weathering shapes the soil and rocks of the earth.

Think about the rain.

• What happens to the land if it continues to rain for many days?

When rain continues for long periods of time, this can cause flooding and create rivers and streams in new places. This may cause rivers in your area to become stronger and faster. As a river becomes higher and moves faster, it wears away the surfaces surrounding it.

Take a look at the example below. The constant flow of the river wears down the edges of the path. The more it rains in the area, the higher this water will rise, and the faster it moves through the area. If this occurs, more and more of the surrounding land will wash away.

Rain water can also seep into tiny cracks in rocks. If this rain water freezes, it can cause the cracks to become bigger, and may even make the rocks break. This is because water expands when it freezes.

Look at the examples of rocks that have large cracks due to weathering:

Wind can cause rocks to weather as well. When wind caries other rocks and soil over a surface, the surface will slowly become worn down from being scratched and scraped by the rocks and soil.

• Have you ever scraped two rocks together, filed your finger nails, or watch someone use sandpaper?

If you have ever seen or done any of these things, you have probably watched part of the weaker or softer of the two things turn to dust or smaller pieces and fall away. This is what happens to surfaces when wind carries rocks and soil over other surfaces.

If rough rocks and soil are blown over softer surfaces, those surfaces become smooth. This can cause the sharp edges of rocks to be rounded off, make holes in rocks, or even change the shape of the rock entirely.

Weathering is a strong force that shapes and changes the earth over time.

Before moving on to the Got It? section, think of two ways the weather in your area might affect the landforms around you.