The friction causes earthquakes and volcanic eruptions near the edges of the plates. The theory that explains this process is called plate tectonics. What are plate tectonics? The theory of plate tectonics is a interesting story of continents drifting from place to place breaking apart, colliding, and grinding against each other.
The plate tectonic theory is supported by a wide range of evidence that considers the earth's crust and upper mantle to be composed of several large, thin, relatively rigid plates that move relative to one another. The plates are all moving in different directions and at different speeds. Sometimes the plates crash together, pull apart or sideswipe each other.
When this happens, it commonly results in earthquakes. Continental Drift: To see this animation again, just refresh this page!
This animation shows you what our planet looked like millions of years ago and what it looks like now! Cinder cones are circular or oval cones made up of small fragments of lava from a single vent that have been blown into the air, cooled and fallen around the vent. Composite volcanoes are steep-sided volcanoes composed of many layers of volcanic rocks, usually made from high-viscosity lava, ash and rock debris.
Rainier and Mount St. It squeezes upward like toothpaste through a tube. Volcanoes can be dangerous—especially to the millions of people around the world who live near one. When a volcano erupts, lava, hot ash, steam, and rocks are released. In addition, volcanic eruptions can cause other natural disasters. These include landslides, mudslides, earthquakes, and tsunamis. The most destructive volcanic event in U. The eruption destroyed entire forests. It killed 57 people.
Mount Saint Helens is located within the Ring of Fire. It is a composite volcano, or stratovolcano. This is the most common type of volcano. It is tall and cone-shaped. A composite volcano is made up of layers of rock and ash. Its eruptions are often violent. Another historically important volcanic event occurred in 79 A. That is when Mount Vesuvius erupted. It buried the city of Pompeii in lava and ash. The city and its people were lost. Centuries later, scientists discovered their remains.
Volcanoes can be destructive. But they can also create new land. The Hawaiian Islands were created by the eruptions of shield volcanoes. These large, low-lying volcanoes are made up almost entirely of layers of hardened lava. Another type of volcano is the cinder cone. These shoot lava into the air like a sputtering fountain.
Lava cools quickly in the air. One example of a cinder cone volcano is Sunset Crater, in Arizona. Volcanoes have played an important role in shaping our Earth. Ash from volcanoes adds helpful minerals to soil. However, where the magma is very sticky, like jam or peanut butter, and if it contains a lot of bubbly gas then the gas can get stuck and eruptions can be very powerful and explosive, like the recent eruptions at Fuego volcano in Guatemala.
In explosive eruptions the frothy, bubbly magma can be ripped apart into tiny bits called volcanic ash. This is not ash like you get after a barbecue or fire, it does not crumble away in your fingers. It is very sharp and is dangerous to breathe in. Some explosive volcanoes can send ash high up into the sky and it can travel around the world over different countries. If aeroplanes travel through an ash cloud from a volcano it can cause a lot of damage to the engine.
Other explosive eruptions create fast-moving, hot clouds of volcanic ash, gas and rocks that travel down the sides of the volcanoes and destroy pretty much everything in their path. Despite the great damage they can cause, volcanoes also help us to live. Volcanic ash provides food for the soil around volcanoes which helps us grow plants to eat.
You can find some more information about different types of volcanoes here and here. Read more: Curious Kids: Do most volcanologists die from getting too close to volcanoes? Hello, curious kids!
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