DESCRIBE THE MAJOR ZONES OF THE EARTH'S INTERIOR.

The earth's interior.

There are three main parts of the earth's interior. The first part is the core, or the center of the earth. The core is divided into two parts. The inner core is solid and the outer core is made of liquid metals, including melted nickel and iron. Within the core, radioactive elements are busy decaying and producing heat. The temperatures and pressure within the core are very high.

The core is surrounded by the earth's mantle. Most of the earth's mass is included in the mantle. The outer twenty-five miles of the mantle make up the earth's crust. Although twenty-five miles might sound like a pretty thick crust, it is really very thin when compared to the depth of the mantle, which is almost 4,000 miles thick. The earth's crust is not a solid shell; instead it is broken into huge pieces that float on top of the soft underlying mantle.

The third element of the earth's interior is composed of huge currents that carry heat from the core through the mantle up to the crust. These currents of melted rock, or magma, flow to the surface and erupt through vents called volcanoes. Once the liquid magma spills out onto the surface of the earth, it is called lava.

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