Have you ever melted butter? It takes about 82 to 97 degrees of heat—about the temperature of a hot summer day. Have you ever melted a rock? Probably not! That kind of melting takes more than 20 times the heat that melts butter! The center of the Earth is hot like that. Rock there melts into a liquid called magma. When the magma bubbles up to the surface, a volcano forms. When the volcano erupts, it spews lava (the word for above-ground magma). Sometimes the lava moves down a mountainside. Then, splash! It enters the sea and turns to new land. What’s happening when the lava comes in contact with the much colder ocean?

First, the hot molten rock makes the ocean boil. As the water boils, it becomes steam and floats into the air. The lava cools down fast, transforming back into rock. The outside surface of the rock feels smooth like glass. But don’t plan to move to the world’s newest land just yet! The new land is not steady. It rests on loose pieces of hardened lava and sand. The ocean could easily wash those away.

Each of the eight major Hawaiian islands is made up of at least one volcano. Some, like the Big Island, are many volcanos combined. Imagine the beginning of the Big Island, which comes from five different volcanos. It started in the center of the Earth as magma. The magma erupted at the bottom of the sea. Then it erupted again. With every new eruption, new rock formed. The volcanos got bigger and bigger until they joined to make one big island. Kilauea, the island’s most active volcano, is still busy erupting. It produces enough lava every day to pave a 20-mile road!