Hobbies And Interests
Eruptions
Just beneath Earth's crust, is a soft, hot layer called the mantle which contains pockets of liquid rock called magma. The magma rises until it reaches a hole in the crust and bursts out in an explosion called an eruption.
Lava Flows
When it reaches the surface, magma is called lava and is classified by the Hawaiian terms "aa" (ah-ah) and "pahoehoe" (pa-hoy-hoy). "Aa" flows are up to 330 feet deep and covered with angular blocks called scoria, making them hard to walk across when they cool. "Pahoehoe" flows are about three feet thick and are smooth like skin when they cool.
Types
Active volcanoes have erupted within the last few hundred years and show signs that they will erupt again. Dormant volcanoes last erupted in the past few thousand years and have the potential to erupt again. Extinct volcanoes haven't erupted in thousands of years and don't show any signs that they will.
Benefits
Although volcanic eruptions are dangerous and frightening, they also provide many benefits. They shape the land, create fertile soil for farming, and generate enough heat to power industrial society for millions of years.