Rocks are everywhere. You can find them along a beach. There are rocks in deserts, on mountains, and in fields. There is rock at the bottom of the ocean. You might find rocks in your own backyard. Even soil is made partly of ground-up rock. Most of Earth’s crust, or outer layer, is made of rock. If you dig down deep enough in the ground, you will find a layer of solid rock. This layer is called bedrock.
Rocks are chunks of solid minerals. Rocks can be red, brown, black, tan, gray, or other colors. Some rocks are plain looking. Some rocks are very beautiful. Some rocks have stripes or speckles.
Have you ever run barefoot through the grass? Have you ever looked at a field of corn? Have you ever planted a flower seed? Grass, corn, flowers, and all other plants need soil in order to grow. Without soil there would be no crops for food, no forests, flowers, or grasslands. You could say that life on Earth depends on soil.
Soil is everywhere around you. Soil covers much of the surface of Earth. The soil in the Midwestern United States is black. The soil in some Southern states is a reddish color. Near deserts, lakes, and oceans, the soil can be gritty and sandy. What a soil looks and feels like depends on how it is formed. Pick up some soil from your yard or a park. Look at its color. Feel if it is gritty or smooth.
Suddenly, the top of a mountain blows off. A ball of fire goes up into the air. Dark clouds of dust, ash, and cinders cover the sky. Rivers of fire pour down the sides of the mountain. This is what can happen when a volcano erupts. Erupting volcanoes have killed thousands of people. The dust and ash have buried whole towns.
Scientists think that more than 1,500 volcanoes have erupted in the past 10,000 years. Mount Vesuvius in Italy erupted in ad 79. It destroyed the city of Pompeii and other Roman towns. Mount Saint Helens, a volcano in Washington State, erupted in 1980. It destroyed the forests around it and killed more than 50 people. Erupting volcanoes have caused terrible disasters.
You wouldn’t want to get caught on the beach at the Bay of Fundy when the tide is coming in. The water rises fast at this bay in southeastern Canada. If you built a six-story building on the beach at low tide, it would be completely under water at high tide. Rivers that empty into the bay run backward as the tide comes in!
Then the tide begins to fall. Water flows out toward the sea. The level of the bay drops. Rivers return to normal. Soon it is low tide. You can see sea animals in shallow pools.
Think about the different ways you use water. You drink water when you are thirsty. You take a bath and wash your clothes with water. You water the grass or other plants. You swim in water. Water pouring over huge dams may even make the electricity that lights up your home.
About three-quarters of Earth’s surface is water. Living things are mostly made up of water. Without water, there would be no life on Earth.
WHAT IS WATER?
Water is a chemical. Chemists say water is a compound, a combination of different materials. Water is a combination of oxygen and hydrogen atoms. An atom is a tiny bit of matter much too small to see.