Lava and Magma: How the Hawaiian Islands Formed by Jeremy Morlock

Author:Jeremy Morlock [Morlock, Jeremy]
Language: eng
Format: epub
Publisher: The Rosen Publishing Group, Inc

ACTIVE, DORMANT, AND EXTINCT

There are three categories of volcanoes: active, dormant, and extinct. These categories are based on what the volcanoes are expected to do. Active volcanoes have erupted recently or are showing signs of activity, such as gas coming from the vent. Dormant volcanoes haven’t erupted in a long time, but they may in the future. They’re in a quiet time between periods of activity. Extinct volcanoes were active long ago, but they’re not expected to erupt again.

The time between volcanic eruptions can be tens of thousands of years. This means it can be difficult to tell if a volcano is actually extinct or if it’s dormant. The Hawaiian archipelago has volcanoes in each category. The Kilauea volcano on the island of Hawaii has been active for more than 35 years.

READING THE ROCKS

THE BIG ISLAND HAS FIVE VOLCANOES: KOHALA, MAUNA KEA, HUALALAI, MAUNA LOA, AND KILAUEA. KOHALA IS THE OLDEST. GEOLOGISTS HAVE STUDIED THE LAYERS OF ROCK FROM PAST ERUPTIONS. THEY THINK KOHALA LAST ERUPTED 60,000 YEARS AGO.

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