Interior of the Earth & Rocks

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The three main layers of the Earth are: (1) Crust – the outermost thin layer, (2) Mantle – the thick middle layer beneath the crust, and (3) Core – the innermost and densest layer made of iron and nic…

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The crust is the outermost solid layer of the Earth, ranging from 5–70 km in thickness. It has two types: (1) Continental Crust – thicker (up to 70 km), made of granite (SIAL: Silica + Aluminium), and…

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Direct study is limited because temperature and pressure increase rapidly with depth. Drilling tools melt under extreme heat—temperature rises by 1°C every 32 meters. The deepest human-made hole is on…

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SIAL stands for Silica (Si) and Aluminium (Al). It refers to the composition of the continental crust, which is lighter (density ~2.7 g/cm³) and forms the continents. Granite is a common SIAL rock.

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SIMA stands for Silica (Si) and Magnesium (Mg). It describes the oceanic crust, which is denser (~2.9 g/cm³) and lies beneath the ocean floors. Basalt is a common SIMA rock.

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NIFE stands for Nickel (Ni) and Iron (Fe). It is the composition of the Earth's core, which is very dense (9.5–14.5 g/cm³). The core generates Earth's magnetic field due to the movement of molten iron…

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The mantle lies beneath the crust and is about 2900 km thick. It has two parts: (1) Upper Mantle – includes the rigid lithosphere and soft asthenosphere (source of magma), and (2) Lower Mantle – deepe…

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The Mohorovicic (Moho) discontinuity is the boundary between the Earth's crust and the mantle. It is marked by a sudden increase in seismic wave speed, indicating a change in rock density and composit…