Earth’s Structure

The Earth’s interior is still a mystery to scientists. So far, scientists have determined that there are four major layers and several minor layers inside of the Earth. You may think that studying the Earth would be a simple process, but even with the greatest technology, geologists and engineers cannot dig a hole through the closest and thinnest layer. If you wanted to dig a hole to the center of Earth you would need a huge drill. The center of Earth is approximately 3,959 miles from the surface.

Scientists have learned a lot of information about Earth’s interior by studying the waves produced in an earthquake, because waves change speed and refract as they travel through different densities. This study has given scientists estimates to where each layer starts and ends. Other information has been inferred through the analysis of the Earth’s rocks and its magnetic field. In this interactivity, you will learn about each of Earth’s interior layers. Click the player button to begin.

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Convection Currents

The intense heat and pressure within Earth’s interior is a powerhouse of energy that affects each of Earth’s systems. The driving force of this energy is convection. Convection is the heat transfer within a liquid, when heated materials rise as cooler materials sink. This process takes place within the Earth. Earth’s core heats the mantle above it and moves heat and material towards the crust. As that materials rises, it cools slightly and begins to sink back towards the core. The movement of heat and material within the mantle powers the movement of the rigid lithosphere above the asthenosphere.  This internal convection powers the movement of Earth’s crust, which causes earthquakes and volcanoes as the plates that make up Earth’s crust move and change over time. How much does the Earth’s crust move per year? It seems that certain areas move more than others. On average, the crust can move anywhere from 10-40 millimeters per year. That is about as fast as your fingernails grow.

 

Earth's Structure Review

Now that you have explored the structure of Earth, complete this activity to review your knowledge. In this non-graded activity, follow the directions associated with each question. Click the player button to get started.