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Volcanoes have split personalities. For most of their long lives, they are quiet.
Their destructiveness makes headlines and history, but their generosity is often unappreciated. Inside the Earth, magma carries many valuable elements such as gold, silver, sulfur, zinc, and copper. As magma cools, some of these elements form minerals in cracks and spaces in the surrounding rocks, where miners discover them. Magma also heats underground water systems that can be tapped to produce heat and electricity. This geothermal power is clean and renewable. Volcanoes give us mountains to ski on, lakes to swim in, and hot springs to soak in. Volcanic landscapes also provide unique homes for animals and plants. And sometimes, layers of volcanic ash and rock preserve important clues about life hundreds or even millions of years ago.
Moneymakers
◀ On the island of Java in Indonesia, farmers have been growing rice in the same plots for centuries. Nearby on Kalimantan (Borneo), farmers have to move their plots every few years. That’s because rain washes away nutrients in the soil that plants need. Java has active volcanoes, but Kalimantan does not. Ash from the active volcanoes helps to renew the soil so farmers can keep planting on it.
▲ Sulfur is used in making rubber, explosives, and fertilizers. It is odorless, but molten sulfur reacts with hydrogen to form hydrogen sulfide, which is poisonous and smells like rotten eggs. There are many sulfur-rich volcanoes in the world. Without sulfur, there could be no life on Earth.
◀ Ol Doinyo Lengai in Africa is the only volcano known to spew out ash that turns into sodium bicarbonate. We call that baking soda. Wind and water carry the unusual ash from Tanzania to Lake Magadi in Kenya, where it is mined.
The Heat Is On
In Beppu, Japan, people cook eggs in one of their city’s 4,000 hot springs. The hot springs are Beppu’s main industry, attracting 12 million visitors a year. A volcanic eruption formed the springs more than 1,000 years ago. ▶
◀ The Geysers, 90 miles from San Francisco, is the world’s largest geothermal plant. It uses steam from the Earth to produce electricity. The steam, piped from wells, powers the blades of a turbine, which drives an electrical generator. When the steam cools, it turns to water—which is pumped back into the Earth, where nature heats it again.
Exclusive Homes
◀ More than 1.5 miles under the ocean surface, 12-foot worms collect around the vents of volcanoes. They dine on bacteria that grow well because of the heat and minerals from the volcanoes.
▲ Silversword plants grow only on the volcanic islands of Maui and Hawaii. An endangered species, the silversword blooms once during its life of 10 years or so.
Buried Treasures
◀ In the ground in Nebraska, paleontologists (scientists who study ancient life) have found fossils of rhinos, three-toed horses, camels, and other animals. Ten million years ago, ash from a volcanic eruption suffocated and buried them. It is one of the largest fossil records we have.
In East Africa, more than 3.6 million years ago, a family left footprints in damp volcanic ash. When the ash hardened, the footprints remained. From this record, scientists learned that these people were some of the earliest human beings to walk upright. The oldest fossils of our human ancestors have been preserved throughout Africa’s Great Rift Valley. ▶
Check It Out!
What does your pencil point have in common with a diamond?
Diamonds and graphite (the point of your pencil) are the same element, carbon. Carbon becomes a hard diamond instead of soft graphite because of volcanic processes. Diamonds form in volcanic rocks deep inside the Earth. Intense pressure squeezes the carbon atoms into a tight network to form the hardest substance on Earth. Without this pressure, carbon forms graphite.
