An interactive cross-section

Inside the Earth

6,371 kilometres from the ground beneath you to the centre of the planet. Nobody has been deeper than 12. Scroll to descend — and click anything you see.

Time after rupture 00:00 P P through inner core S
Scroll to descend
The whole planet

A wedge out of the sphere

The same layers in three dimensions. Drag to turn the globe; click a layer, the surface or a field line. On the cut faces the outer core’s convection columns run parallel to the spin axis — the geometry that makes the field a dipole.

The numbers

Earth, measured from the inside

Seismic velocities and density are the Preliminary Reference Earth Model (PREM), fitted to travel times and free oscillations. Pressure and gravity are integrated here from that density. Temperature is the least certain curve — the band shows the spread of published estimates. Hover to read any depth.

Values at the main boundaries (table)
Read this before you cite it

What is exact, what is schematic

Computed, not drawn

  • Layer depths, velocities and densities follow PREM. Note PREM places the transition-zone discontinuities at 400 and 670 km; the globally averaged depths used on the cards are 410 and 660 km.
  • Pressure and gravity are integrated from PREM density in your browser (centre: 364 GPa; gravity peaks at the core–mantle boundary).
  • Seismic rays are traced through PREM with a constant ray parameter. The shadow zones you see are a consequence of the velocity model, not an illustration.
  • “True scale” is true: radii are linear in depth and nothing is thickened.

Schematic on purpose

  • The cross-section is a generic plate boundary — ridge, hotspot, trench, arc, craton — not a real transect. In “Exaggerated” mode shallow layers are stretched vertically (up to ~18× in the crust), which steepens every dip.
  • Colours are symbolic. Real mantle rock at depth would glow dull orange-white; here each layer has its own hue (olivine green, ringwoodite blue) so you can tell them apart.
  • Convection is drawn as four tidy cells. The real flow is three-dimensional, time-dependent, and tens of trillions of times slower than the animation.
  • The magnetic field is a pure tilted dipole. The real field has non-dipole parts and is swept into a tail by the solar wind beyond a few Earth radii.
  • Clouds on the globe are procedural. Earth’s 23.4° axial tilt is not shown.

Still debated

  • Core temperatures (±500 K), the age of the inner core (≈0.5–1.5 Gyr), and how much heat crosses the core–mantle boundary (≈5–15 TW).
  • What the two large low-velocity provinces are made of, and how long they have been there.
  • How much water the transition zone actually holds, and whether every hotspot sits on a deep plume.
  • The size and origin of the innermost inner core, and how the inner core’s rotation drifts relative to the mantle.

Sources

  1. Dziewonski & Anderson (1981). Preliminary reference Earth model. Phys. Earth Planet. Inter. 25, 297–356.
  2. Kennett, Engdahl & Buland (1995). Constraints on seismic velocities in the Earth from traveltimes (ak135). Geophys. J. Int. 122, 108–124.
  3. Lehmann (1936). P′. Publ. Bur. Cent. Séismol. Int. A14, 87–115.
  4. Katsura et al. (2010). Adiabatic temperature profile in the mantle. Phys. Earth Planet. Inter. 183, 212–218.
  5. Anzellini et al. (2013). Melting of iron at Earth’s inner core boundary. Science 340, 464–466.
  6. Murakami et al. (2004). Post-perovskite phase transition in MgSiO₃. Science 304, 855–858.
  7. Pearson et al. (2014). Hydrous mantle transition zone indicated by ringwoodite included within diamond. Nature 507, 221–224.
  8. Garnero, McNamara & Shim (2016). Continent-sized anomalous zones with low seismic velocity at the base of Earth’s mantle. Nat. Geosci. 9, 481–489.
  9. Davies & Davies (2010). Earth’s surface heat flux. Solid Earth 1, 5–24.
  10. Lay, Hernlund & Buffett (2008). Core–mantle boundary heat flow. Nat. Geosci. 1, 25–32.
  11. Pham & Tkalčić (2023). Up-to-fivefold reverberating waves through the Earth’s center and distinctly anisotropic innermost inner core. Nat. Commun. 14, 754.
  12. Yuan et al. (2023). Moon-forming impactor as a source of Earth’s basal mantle anomalies. Nature 623, 95–99.
  13. U.S. Standard Atmosphere (1976). NOAA / NASA / USAF.
  14. Surface imagery: NASA Earth Observatory, Blue Marble Next Generation (public domain).