24 How Earthquakes and Volcanoes Shape Earth

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How Earthquakes and Volcanoes Shape Earth by BARBARA COLLIER With the Editors of TIME FOR KIDS

CHAPTER 1 Our Home the Earth Roar! An earthquake shakes the ground. Crash! A tree falls down. Whoosh! A volcano explodes. Lava pours down the sides. Lava is a very hot liquid rock. It destroys everything in its path. Volcanoes and earthquakes are natural disasters. A natural disaster is a force of nature. It can cause harm, or destroy things. A hurricane is a natural disaster. A tornado is a natural disaster, too. Maybe in the future people will stop natural disasters. But is that a good thing? Maybe not. Earthquakes and volcanoes can be bad. But they can be good, too. To understand this, we can learn how Earth is put together.

CHAPTER 2 Our Planet is a Puzzle A rock crust covers Earth. Very large pieces of rock form that crust. We call these pieces tectonic plates. They fit together like pieces of a jigsaw puzzle. They float over a layer of hot, melted rock. Earth's continents cover some of these plates. The oceans cover the others. The plates move slowly. Usually, you cannot tell they move. Imagine a lake filled with big floating rafts. Some rafts bump into each other. Other rafts float apart. Earth's plates float like these rafts. The plates meet in one place. This place is called a fault. Many earthquakes and volcanoes happen near faults.

CHAPTER 3 When the Earth Shook Earthquakes and volcanoes cause great harm. But they also helped to shape Earth. About 250 million years ago, Earth had just one big piece of land. There was ocean around the land. Then Earth shook and things crashed. Lava poured out of holes in the ground. The earthquakes and volcanoes helped break the land into smaller pieces. Now, millions of years later, we have continents. When Earth was a new planet, there was no air to breathe. For millions of years, volcanoes erupted, or poured out lava. Gases from inside Earth poured out. Those gases made the air we breathe. Then life began on Earth.

CHAPTER 4 Volcanoes Two tectonic plates can grind together at a fault. One can slide under the other and get stuck. There is a hot layer of rock below Earth's crust. It heats the end of the plate. The end of the plate melts. It mixes with bubbles of gas. Hot lava bursts out of the ground. A volcano forms! When a volcano erupts, big rocks, ash, and hot gases burst out with the lava. A volcano can destroy everything around it. Another Look In some places, we use heat from liquid rock inside Earth to make electricity. That is good. But this liquid rock is lava. Lava can cause much harm when a volcano erupts. Almost 2,000 years ago, Pompeii was a town in Italy. It was near a beautiful mountain called Mount Vesuvius. The mountain was really a volcano. But its last eruption was hundreds of years earlier. Suddenly, the top of the quiet mountain blew! People tried to run away. But rocks, ash, and lava buried the town and all the people. Pompeii is a sad example of how volcanoes can cause great harm.