The Earth’s interior includes three sections: the crust, the mantle and the core. The thickness and composition of these layers varies greatly. The crust ranges in depth from 6.5 to 25 miles thick and is made mostly of rock and other loose materials. Directly beneath the crust and extending for about 1,800 miles, the mantle is composed of a thick rock-like substance. The Earth’s core is divided into two layers – the inner and outer cores. The outer core is approximately 1,370 miles thick. At a temperature of around 4500 degrees Fahrenheit, it remains liquid and rotates around the solid inner core, which is approximately 780 miles thick. Both the inner and outer cores are primarily iron and nickel with small amounts of other elements and gasses.
To create a model of the Earth’s interior you will need:
• 1 medium to large-sized Styrofoam ball
• Box knife or similar cutting tool
• Pen or pencil
• Compass
• Markers, paint or other decorative items
Cut the ball in half. Mark a dot in the approximate center of the hemisphere. Using a compass and a pen or pencil, draw three circles (moving from the center out) to represent the sections of the Earth’s interior. Make the circles different widths to represent the thicknesses of the different layers. If desired, include an extra circle to indicate the division between the inner and outer cores.The crust section should be thin. The mantle section should cover approximately 45% of the distance from the outer edge to the center. The outer core should cover about 30% of that same distance while inner core occupies about 20%. It's fine to approximate these widths, but the widths of the layers should be different enough to indicate their varying sizes. Using paint, markers or other decorations, fill in each circle in a different color. Label the sections appropriately.
To create more visual variety in your project, consider adding more detail to your model. Instead of cutting the ball in half, remove one quarter of the ball to create a cut-away diagram. Decorate the outside surface of the ball to represent the Earth’s surface, complete with oceans and continents. Use materials that represent the contents of each of the earth’s layers. Fill in the section for the crust with loose gravel or small rocks, use plaster to represent the mantle and small pieces of metal to illustrate the core. Use a melon baller to hollow out the section for the inner core and insert a marble or small rubber ball to indicate that the inner core is solid.