This passage describes how volcanoes are formed and when they will erupt.

Lexile Level: 900L

Categories: Science & Technology Animals & Nature

The earth's surface is composed of big slabs of rock called plates. Volcanoes are formed when plates move apart. Magma, hot liquid from the center of the earth, rises when this happens and forms new rock along the edges of the plates. The new rock builds and forms the shape of a cone, sometimes with lava inside. Scientists are very good at predicting when a volcano will erupt. Indonesia and Japan are known for having the most active volcanoes. The U.S. ranks third, with fifty volcano eruptions. More than 500 explosions have occurred worldwide. Sometimes volcanoes erupt without anyone noticing, especially volcanoes on the ocean floor. Scientists also think there are volcanoes in space that erupted billions of years ago. Space probes have found evidence of eruptions on Mars and Mercury. Mars has the largest volcano in the solar system. Eruptions on other planets are mostly of a rocky material instead of lava.


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