What Is Earth's Internal Composition?

When the French author, Jules Verne, wrote his fictional "Journey to the Center of the Earth," he was wrong about the internal composition of the planet. It gets hotter at the core which is solid metal. This is surrounded by molten metal above which the continental crust and the oceanic crust floats. Humans live on the earth's surface, a relatively thin layer that is exposed to the atmosphere and to the warmth and light from the sun.

Size

The earth is a spherical planet with an internal diameter at the equator, its widest point, of 7926.41 miles. If you measured the internal distance between the north and the south poles, though, you would find it to be 7899.83 miles. The highest point on the earth's surface is Mount Everest, at 29,028 feet, and the lowest point is the Mariana Trench in the Pacific Ocean at 36,198 feet below sea level.

Features

The earth's surface is made up of rocks. The land, or the continental crust, is predominantly made of granite. The sea's floor, the oceanic crust, is basalt. An area known as the Mohorovicic Discontinuity, Moho for short, is a thin layer between the earth's crusts and the mantle.

Identification

The earth's mantle extends for 1800 miles beneath the surface. The rocks in the mantle contain silicon, oxygen, aluminum, iron, and magnesium. An soft area called the asthenosphere goes from the top of the mantle down about 60 miles. Under this is a tougher area called the lithosphere. Nearest the core of the earth, the temperature rises to as much as 7850 degrees F. At this temperature, the rocks melt.

Considerations

For every additional mile of depth, the internal temperature of the earth rises by 3 degrees F. The pressure also increases at deeper places in the earth. This causes the rocks to assume more dense forms.

Expert Insight

The center of the earth, called the core, is divided into two parts. The outer core is a mass of molten liquid nickel and iron. Even though the temperature at the inner core of the earth reaches 12,600 degrees F, the tremendously increased pressure there forces the iron and nickel to solidify. So, the internal composition of the earth is made up of layers of very hot minerals under increasingly higher pressure. When heat is released from the core, it can trigger earthquakes and volcanoes on the earth's surface.