Herbert Farker, age 11, of Gallatin, Tenn., for his question;
What is a dead volcano?
The rocky crust of our earth is always being changed and remodeled. Most of the work is done slowly and in a human lifetime. We do not notice the changes but volcanoes are fast builders. A newborn volcano can build a mountain 1400 feet high before it is ten years old.
A volcano may lead a busy and active life for a short ten or twenty years. It may be active for hundreds of years. During its active life, it may send up p1umes of smokey gases, flames and shooting sparks every day and night. Or it may erupt with fury and then rest for hundreds of years before it erupts again. But sooner or later, the seething fury comes to an end and the active life of the volcano is over.
When a volcano rests a long time between eruptions, ate say that it is dormant, which means s1eeping. A quiet volcano may be dormant, just waiting to explode again. When all the energy is spent forever, we say that the volcano is extinct, which means that it is dead and done for. Peop1e often think that a dormant volcano, quiet for ages, is extinct. Then it erupts and they get a sudden surprise.
A volcano begins in cracks and pockets miles below the ground. Deep forces in the earth cause the buried rocks to become hot, hot enough to melt. They form pools of magma made of molten minerals, gases and seething steam. The hot magma expands and pushes up through a hole called a vent.
The seething mixture may erupt through the mouth or crater of the volcano and spill rivers of red hot lava over the land. It may seep between underground layers of rock and never reach the surface. Sooner or later, the molten mixtures cool and harden into solid rocks. An active volcano may build a high, pointed mountain called a cone. It may spread a new layer of rock on the surface, or it may add new layers of rock deep underground.
Long after the volcano is extinct, these fire formed rocks remain to tell its story. Its vents become plugged with cindery ashes. If the volcano built a mountain, its crater may fill with water and form a lofty lake to reflect blue sky. After many thousands of years, the extinct cone is worn down by wind and weather. Running streams often dig deep canyons, which show the layers of fire formed rock that came from underground volcanoes.
A years ago, a new volcano was born in Mexico. It started as a smoking hole in a corn field. After ten years, it had built a mountain 111.00 feet high. They named it Paricutin, for the first village it covered with debris. Paricutin is now dormant and it may be extinct. But nearby there are the cones of hundreds of extinct volcanoes. Like Paracutin, they were once active. For a while they were crowned with plumes of smoke and clouds of flame, and sprays of sparks shooting into the sky like Roman Candles.