Where diamonds grow
About 98 in every 100 diamonds formed between 150 and 200 km down, under the oldest parts of continents, and rode up in rare, fast eruptions.
Surface to Core
6,371 km straight down.
One screen is 100 km, all the way. That makes 64 screens to the centre. Keep scrolling: the page gets darker, then hotter.
Pressure is shown in atmospheres: 1 atm is the weight of the air at sea level. Depths and pressures come from seismology. Temperatures deep down are estimates, and scientists still argue about them. Sources
The first 100 km
- 59 m
Hampstead station
The deepest station on the London Underground, 58.5 m below the street.
- 1.1 km
Boulby mine
The deepest mine in Great Britain, on the North Yorkshire coast. Physicists hunt for dark matter in a laboratory 1.1 km down.
- 4 km
Mponeng gold mine
In South Africa, the deepest place people go to work. The rock is 66 °C, so the tunnels are cooled with ice slurry.
- 8.8 km
Everest, upside down
The highest mountain is 8,849 m tall. Turned over, it would reach this far.
- 10.9 km
Challenger Deep, for scale
The deepest point of the ocean is 10,935 m below sea level, in the Mariana Trench.
- 12.3 km
Kola Superdeep Borehole
The deepest hole ever dug, in Arctic Russia. 23 cm wide, 12,262 m deep, reached in 1989 after 19 years of drilling. At the bottom the rock was about 180 °C.
- 23 km
Britain’s biggest earthquake
The Dogger Bank earthquake of 7 June 1931, magnitude 6.1, started about 23 km under the North Sea.
- 30 km
The Moho
The bottom of the crust. Earthquake waves suddenly speed up here, which is how Andrija Mohorovičić found it after an earthquake in 1909.
- 80 km
The plates end
The rigid outer shell, crust and the top of the mantle together, is at least 80 km thick over much of the Earth. Below it, rock is soft enough to flow.
410 kmUpper mantle ends. Transition zone begins.
660 kmTransition zone ends. Lower mantle begins.
2,891 kmLower mantle ends. Outer core begins.
5,150 kmOuter core ends. Inner core begins.
The transition zone
Olivine, the green mineral of the upper mantle, is squeezed into denser crystals. A diamond from Brazil carried up a crystal from this depth that was about 1.5% water by weight.
You have now fallen further than the International Space Station flies above you, about 400 km.
London to Edinburgh
As far down as Edinburgh is from London in a straight line.
The lower mantle
The minerals change again, into bridgmanite, the most common mineral on Earth. It cannot survive at the surface, and the first natural grains were only found in 2014, inside a meteorite.
The deepest big earthquake
On 30 May 2015 a magnitude 7.9 earthquake started about 680 km under the Bonin Islands, south of Japan. Below here, rock no longer breaks. It only flows.
London to Moscow
As far down as Moscow is from London.
The core
Rock ends and liquid metal begins. The density nearly doubles, the sharpest change anywhere inside the planet. The liquid iron churns, and that is what makes compasses point north.
Further than London to Moscow.
London to Cairo
As far down as Cairo is from London.
The inner core
Solid again. It is hotter here than in the liquid above, but the pressure is so great that the iron cannot melt. Inge Lehmann worked out it was there in 1936, from faint earthquake waves that arrived where none were expected.
Further than London to Lagos, 5,012 km.
London to New York
As far down as New York is from London.
The centre
About 3.6 million times the air pressure at sea level. Somewhere between 5,200 and 6,000 °C, close to the temperature of the Sun’s surface. And no up or down: you would weigh nothing.
You fell 6,371 km.
The deepest any person has been is about 4 km down a mine. The deepest any drill has reached is 12.3 km. Everything below that is known from earthquake waves, from lab experiments that squeeze tiny samples between diamonds, and from the rare rocks that eruptions carry up.
Sources for this page
Distances between cities are our own great-circle sums. Temperatures follow a typical continental profile in the crust, the mantle profile of Katsura and others (2010), about 4,000 K at the top of the core (Lay and others, 2008) and 5,500 to 6,230 K at the inner core boundary (ESRF 2013; Anzellini and others, 2013), joined with straight lines. Pressures are from PREM. The colours of the page are chosen for the site; nobody knows what colour the deep Earth would look.
- Hampstead tube station Wikipedia, citing Transport for LondonThe deepest station on the London Underground, 58.5 m below ground
- Boulby Underground Laboratory Science and Technology Facilities CouncilBoulby is the deepest mine in Great Britain; its laboratory is 1.1 km down
- Gold standards (March 2011), via Wikipedia: Mponeng Gold Mine N. Wadhams, Wired 19(3)Mponeng is about 4 km deep and its rock reaches 66 °C
- Mount Everest Wikipedia, citing the 2020 Nepal and China joint surveyEverest is 8,848.86 m high
- How deep is the ocean? NOAA Ocean ExplorationChallenger Deep is 10,935 m deep; the average ocean is 3,682 m deep
- Deepest borehole Guinness World RecordsKola Superdeep Borehole, 12,262 m, reached in 1989, 23 cm wide
- Kola Superdeep Borehole WikipediaDrilling began in 1970; about 180 °C at the bottom
- Historical earthquake: 7 June 1931, North Sea (Dogger Bank) British Geological SurveyThe largest known UK earthquake, magnitude 6.1 ML, 23 km deep
- This Dynamic Earth: Inside the Earth US Geological SurveyContinental crust averages about 30 km, up to 100 km under big mountain ranges; ocean crust about 5 km; lithosphere at least 80 km
- Mohorovičić discontinuity Wikipedia, citing A. Mohorovičić (1910)Andrija Mohorovičić finds the base of the crust from the 8 October 1909 earthquake
- Diamond Reflections, Fall 2023 Gemological Institute of America, Gems & GemologyAbout 98% of diamonds form 150 to 200 km down under old continents
- Hydrous mantle transition zone indicated by ringwoodite included within diamond (2014) D. G. Pearson and others, Nature 507A ringwoodite crystal from the transition zone holding about 1.5% water by weight
- Adiabatic temperature profile in the mantle (2010) T. Katsura and others, Physics of the Earth and Planetary Interiors 183Temperatures of about 1,800 K at 410 km and 1,900 K at 660 km
- Preliminary reference Earth model (1981) A. M. Dziewonski and D. L. Anderson, Physics of the Earth and Planetary Interiors 25Depths of the core (2,891 km) and inner core (5,150 km), densities and pressures down to the centre
- Discovery of bridgmanite, the most abundant mineral in Earth, in a shocked meteorite (2014) O. Tschauner and others, Science 346Bridgmanite is the most common mineral in the Earth; first natural grains found in the Tenham meteorite
- The isolated ~680 km deep 30 May 2015 Mw 7.9 Ogasawara (Bonin) Islands earthquake (2016) L. Ye and others, Earth and Planetary Science Letters 433The deepest large earthquake on record, about 680 km down
- Continent-sized anomalous zones with low seismic velocity at the base of Earth’s mantle (2016) E. J. Garnero, A. K. McNamara and S.-H. Shim, Nature Geoscience 9Two continent-sized regions at the base of the mantle, under Africa and the Pacific
- Core-mantle boundary heat flow (2008) T. Lay, J. Hernlund and B. A. Buffett, Nature Geoscience 1About 4,000 K at the top of the core, give or take 500
- Inge Lehmann Wikipedia, citing I. Lehmann (1936), “P′”, Bureau Central Séismologique International A14Inge Lehmann finds the solid inner core in 1936
- Melting of iron at Earth’s inner core boundary based on fast X-ray diffraction (2013) S. Anzellini and others, Science 340Iron melts at about 6,230 K (about 5,960 °C) at the inner core boundary
- Earth’s core is hotter than thought (press release on Anzellini 2013) European Synchrotron Radiation FacilityAllowing for light elements, about 5,500 K (about 5,200 °C) at the inner core boundary