The outer core is liquid and made mostly of iron and nickel. As it moves, it creates Earth's magnetic field through a process called the dynamo effect.[21] The inner core is solid and also made mostly of iron and nickel. It stays solid because the pressure at the center of the Earth is extremely high.[22] The way the Earth is built on the inside helps explain the theory of plate tectonics. This theory says that the plates of the lithosphere move over time, and this movement shapes the Earth’s surface. For example, at the Mid-Atlantic Ridge, new ocean floor is made as plates move apart. At the San Andreas Fault in California, two plates slide past each other, which causes earthquakes.[23][24] Rocks and minerals Geologists, who are scientists that study the Earth, group all Earth materials into two main categories: rocks and minerals. Rocks are made up of one or more minerals, and they can change from one type to another over time through a process called the rock cycle. There are three main types of rocks: igneous, sedimentary, and metamorphic. Igneous rocks form when melted rock, known as magma (if it is underground) or lava (if it's on the surface), cools and hardens.

That is more than 50 million years, from 312 to 262 million years ago (mya).[6] The magnetic field had reversed polarity. The name "Kiaman" derives from the Australian village of Kiama, where some of the first geological evidence of the superchron was found in 1925.[7] Causes The magnetic field of the Earth, and of other planets that have magnetic fields, is caused by dynamo action of molten iron in the planetary core. This convection (movement) generates electric currents which in turn give rise to magnetic fields.[6] In simulations of planetary dynamos, reversals occur from the underlying dynamics. For example, Gary Glatzmaier and collaborator Paul Roberts of UCLA ran a numerical model of the coupling between electromagnetism and fluid dynamics in the Earth's interior. Their simulation reproduced key features of the magnetic field over more than 40,000 years of simulated time and the computer-generated field reversed itself.[8][9] Global field reversals at irregular intervals have also been observed in a laboratory liquid metal experiment VKS2.[10] Effects on life As far as we know, there is no effect on life.

Earth’s magnetosphere is generated by convective dynamo action within its liquid metallic outer core. This same core-driven dynamo process has been inferred for other terrestrial planetary bodies which either presently possess a magnetosphere, or may have in the past. These bodies include Ganymede, Mercury, the Moon, and Asteroid 4 Vesta. However, understanding these core processes requires that the core composition be known. By experimentally determining the solid-liquid phase transitions of core-relevant alloys, the likely compositions of these terrestrial cores may be constrained.            Experiments were conducted on 8 Fe-Si alloys in the range of Fe-5 wt% Si to Fe-33 wt% Si (FeSi) using a 1000-ton cubic anvil press, at pressures of 3-5 GPa and temperatures into the liquid state. A central 5-hole BN cylinder held 5 different Fe-Si sample compositions simultaneously with a thermocouple located at the base of the BN cylinder, and was surrounded by a graphite furnace within a pyrophyllite cubic pressure cell. Following quenching of each experiment, the samples were analysed by electron microprobe for composition and texture. From these analyses, the solidus and liquidus boundaries were mapped across the aforementioned compositional range at of 3, 4, and 5 GPa.            It was determined that the melting boundary for 3-5 GPa was roughly 50-150 K higher than that of 1 atm, with a eutectic composition of Fe-20 wt% Si. Across the 3-5 GPa range, there was an increase in the melting boundary of roughly 50-75 K. Using pressure and temperature estimates from previous core modelling studies, a range of approximately 10-15 wt% Si was suggested for the core of the Moon.