Layer of the upper mantle with a thickness of 200 km; it is composed of molten rock, on top of which the lithospheric plates slide.
Mohorovicic discontinuity
Zone that separates the Earth’s crust from the asthenosphere.
Gutenberg discontinuity
Zone separating the lower mantle from the core; it is located at a depth of about 2,900 km.
lower mantle
Little-known layer with a thickness of about 2,290 km; its slow-moving currents, called convention currents, are caused by temperature variations.
outer core
Composed of molten metal, it is 1,820 km thick; the magnetic field is caused by electric currents circulating inside the outer core.
inner core
Composed of iron and nickel, it is subject to so much pressure that it remains in a solid state in spite of temperatures higher than 5,000°C; its diameter is 1,600 km.
oceanic crust
Layer forming the ocean floor; it is thinner, denser and younger than the continental crust.
