Subskill: Reading Comprehension
Concept: Cause and Effect
Grade Level: Upper Elementary
Ever since ancient times, man has both admired and feared the powerful force of volcanoes. In the year 79 AD, Mount Vesuvius erupted and destroyed the Roman cities of Pompeii and Herculaneum. Early Romans believed volcanoes were caused by Vulcan, the god of fire. Today we know a volcano is an opening in the surface of the earth through which hot, melted rock (magma), ash and gasses erupt.In 1980, a powerful volcano occurred in the State of Washington. Mount St. Helens erupted after being quiet for 123 years. This was one of the most violent volcanic eruptions ever recorded in North America. Almost 230 miles of beautiful, green forestland was scorched, 150 miles of which was completely blown over.
Scientists who study volcanoes are called volcanologists. Volcanologists now believe that most volcanoes form along plate boundaries. This is caused by the movement of plates deep within the earth at its mantle. Magma pushes the plates apart as it melts through the weak borderline between them, forming a volcano.
How do volcanoes affect our planet?
The eruption of volcanoes can be very destructive because they have the potential to kill people and animals and destroy land, but there are also positive effects. Volcanic eruptions release important gases into the air that would otherwise remain trapped inside the earth’s surface, including carbon dioxide.
They also provide a wealth of natural resources, such as, pumice, boric acid, and ammonia. Pumice is a white rock that can be ground into a powder and used for polishing and scrubbing. The ash that comes from volcanoes is nutrient-rich and good for plant growth. This is why farmers usually return to the fertile slopes of volcanoes to begin growing crops again. Most of the homes in Reykjavik, a city in Iceland, are heated by hot water tapped from volcanic springs.
In addition, volcanoes have the effect of shaping the land on which we live by forming islands. Hawaii, Japan and many other islands are actually volcanoes that formed from the ocean floor and reached the surface.
Here are some questions to ask after listening to the article:
What is a cause of volcanoes?
What causes the plates deep within the earth to push apart?
What is a positive effect of volcanic eruptions on our planet?
What are scientists who study volcanoes called?