Outer core Outer core The outer core of the Earth is a fluid layer about thick and composed of mostly iron and nickel that lies above Earth's solid inner core and below its mantle. Its outer boundary lies beneath Earth's surface. The transition between the inner core and outer core is located approximately beneath the Earth's surface. Unlike the inner core, the outer core is liquid. The inner core is also referred to as the solid core. Seismic inversions of body waves and normal modes constrain the radius of the outer core to be 3483 km with an uncertainty of 5 km,
Continental crust Continental crust Continental crust is the layer of igneous, sedimentary, and metamorphic rocks that forms the continents and the areas of shallow seabed close to their shores, known as continental shelves. This layer is sometimes called "sial" because its bulk composition is richer in silicates and aluminium minerals and has a lower density compared to the oceanic crust, called "sima" which is richer in magnesium silicate minerals and is denser. Changes in seismic wave velocities have shown that at a certain depth (the Conrad discontinuity), there is a reasonably sharp contrast between the more felsic upper continental crust and the