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May 24, 2017 · Scientists have found two enormous, mysterious blobs of super-hot material that lie under the earth’s crust. In this visualization, seismic wave paths are shown passing through the blob. The blue and red features represent, respectively, high- and low-velocity material, discovered from tomography. Visualization by Ed Garnero.
Jun 12, 2014 · A reservoir of water three times the volume of all the oceans has been discovered deep beneath the Earth’s surface. The finding could help explain where Earth’s seas came from.
- Andy Coghlan
- Overview
- Inside the Earth
- River of Rock
Learn about the layers inside the Earth, inaccessible to humans.
The Earth's interior is composed of four layers, three solid and one liquid—not magma but molten metal, nearly as hot as the surface of the sun.
The deepest layer is a solid iron ball, about 1,500 miles (2,400 kilometers) in diameter. Although this inner core is white hot, the pressure is so high the iron cannot melt.
The iron isn't pure—scientists believe it contains sulfur and nickel, plus smaller amounts of other elements. Estimates of its temperature vary, but it is probably somewhere between 9,000 and 13,000 degrees Fahrenheit (5,000 and 7,000 degrees Celsius).
Above the inner core is the outer core, a shell of liquid iron. This layer is cooler but still very hot, perhaps 7,200 to 9,000 degrees Fahrenheit (4,000 to 5,000 degrees Celsius). It too is composed mostly of iron, plus substantial amounts of sulfur and nickel. It creates the Earth's magnetic field and is about 1,400 miles (2,300 kilometers) thick.
The next layer is the mantle. Many people think of this as lava, but it's actually rock. The rock is so hot, however, that it flows under pressure, like road tar. This creates very slow-moving currents as hot rock rises from the depths and cooler rock descends.
The mantle is about 1,800 miles (2,900 kilometers) thick and appears to be divided into two layers: the upper mantle and the lower mantle. The boundary between the two lies about 465 miles (750 kilometers) beneath the Earth's surface.
The crust is the outermost layer of the Earth. It is the familiar landscape on which we live: rocks, soil, and seabed. It ranges from about five miles (eight kilometers) thick beneath the oceans to an average of 25 miles (40 kilometers) thick beneath the continents.
Currents within the mantle have broken the crust into blocks, called plates, which slowly move around, colliding to build mountains or rifting apart to form new seafloor.
Continents are composed of relatively light blocks that float high on the mantle, like gigantic, slow-moving icebergs. Seafloor is made of a denser rock called basalt, which presses deeper into the mantle, producing basins that can fill with water.
Except in the crust, the interior of the Earth cannot be studied by drilling holes to take samples. Instead, scientists map the interior by watching how seismic waves from earthquakes are bent, reflected, sped up, or delayed by the various layers.
- The core. Let’s start at the very centre of the Earth. The word ‘core’ means the central part of something, for example, an apple has a core. The Earth has an inner core and an outer core.
- The mantle. The next layer is called the mantle. It is made of rock. It is very hot in this part of the Earth, causing the rock to behave a little bit like a liquid and a solid.
- The crust. The crust is the part of the Earth that we walk on. Compared to the other layers, it is quite thin and breakable. You can think of the crust of the Earth as being a bit like the crust of a pie – although this crust is 5–70 km deep depending on whether you are under the ocean or on top of a mountain!
- Tectonic plates. Scientists think that the crust of the Earth is made up of six large (major) tectonic plates and a few smaller ones. These plates fit together like puzzle pieces and float on the partially molten mantle.
Dec 8, 2023 · The Earth’s interior can be divided into three main layers: the crust, the mantle, and the core. These layers have distinct properties and compositions, which play a significant role in shaping our planet’s geology and behavior. Crust: The Earth’s crust is the outermost layer and the one we interact with directly.
Nov 17, 2020 · There are four main layers to the Earth: crust, mantle, outer core and inner core, along with transition zones between these layers. The world we know lies on tectonic plates making up the Earth’s crust, which varies in thickness from three miles to over 40.
Jun 11, 2024 · Earth’s core is the very hot, very dense center of our planet. The ball-shaped core lies beneath the cool, brittle crust and the mostly solid mantle. The core is found about 2,900 kilometers (1,802 miles) below Earth’s surface, and has a radius of about 3,485 kilometers (2,165 miles). Planet Earth is older than the core.
