Earth’s layers — Earth science, 11–13 years
Earth is not a solid ball made of one material. Its layers have different temperatures, materials and behaviours, and scientists use clues from the surface to investigate what lies below.
A layered planet
Earth is built in broad layers: the thin crust, the hot mantle, the liquid outer core and the solid inner core. These are not neat shells you could cut open with a knife; they are regions whose materials and conditions change with depth.
Why divide Earth into layers?
People cannot drill anywhere near the centre: the deepest boreholes reach only a tiny distance compared with Earth’s radius. Scientists needed a way to explain earthquakes, volcanoes and Earth’s magnetic field, so they used earthquake waves and other evidence to map hidden regions.
Reading a seismic clue
Suppose a seismic station records a wave that travels through solid rock but not through liquid. Scientists compare its arrival at different stations and find that it disappears across part of the Earth. That pattern supports the idea of a liquid outer core, rather than proving that anyone has seen it directly.
The layers are not all solid
A common mistake is to picture every layer as hard rock, because maps and diagrams use solid colours and lines. That is reasonable: the crust and much of the mantle are solid. But the outer core is liquid, while the inner core is solid because enormous pressure changes how iron behaves.
A model for real investigations
This layered model helps geologists interpret earthquake recordings, volcanic activity and Earth’s magnetic field. It also helps engineers think about heat moving through the planet. The model is useful because it makes invisible structure testable, not because it is a photograph of the inside.
Keep exploring
Other languages
Loading MyLeoNes™…