By Imogen Imbrignite Long ago, people used to think that volcanoes were caused by spirits or gods. The word volcano itself comes from Vulcan, who was the Roman god of fire. In the 1600's, they thought that volcanoes might be connected to a fire in the centre of the earth. Today, we know that volcanoes occur above thin parts of the earth's crust. The crust floats on top of molten rock called magma. Most of the time the crust is solid enough for us to stand on. But when an eruption happens, magma rises to the earth's surface and spills out onto the crust as lava. Superheated Science Question: What do you think causes a volcano to erupt? Normally we put volcanoes into three groups, active, dormant and extinct. An active volcano is one that has fairly regular eruptions. A dormant volcano is one that was active in the past, but is now quiet. If a volcano has not erupted in a very long time, and is not likely to do so again, then it is an extinct volcano. Eruptions can cause a lot of damage to towns, cities and even countries! However, living near a volcano can also have many benefits. Eruptions leave large amounts of nutrients on the earth's soil which is good for farming. Volcanic features such as hot springs can also be used as a source of hot water, or even electricity. One of the most famous volcanoes you'll hear about is called the Yellowstone Caldera (1). This large volcano is found in Yellowstone National Park in America. What is a caldera? Good question! A caldera is a huge bowl-like "dip" in the earth's surface. The volcano sits in the middle of this dip. Calderas are made when extremely large eruptions cause the volcano to collapse in on itself. The Yellowstone Caldera last erupted nearly 200,000 years ago. Since then it has become a home for many species of wildlife, such as bears, wolves and bison. Humans also live nearby. The park is open for visitors to learn more about the Yellowstone area and volcanoes in general. It also has many other features to explore, such as spouting jets of water called geysers. Don't be too worried about the volcano erupting while you're there. Scientists are keeping a very close eye on it. If they spot any signs an eruption is about to happen they'll issue a warning. People can then get to safety. At the moment, they think that an eruption is unlikely, so the park is open for people to learn and explore. If you want to learn more about volcanoes, eruptions and lava, then check out this episode by Bill Nye the science guy: Remember to credit your sources and give a scientist a smile!
(1) https://www.nps.gov/yell/index.htm
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