Croatia 2024-Minerals And Rocks - Miniature Sheet (MNH)
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The science that explores the formation and classification of rocks is called petrology. An important point to note is that rocks make up the lithosphere – a solid mass of rocks with a thickness of 5 to 70 kilometers, which encompasses the Earth’s crust (the solid surface layer of the planet Earth) and the Earth’s upper mantle (the thickest layer containing the majority of our planet’s material). Just beneath the solid lithosphere lies the central part of the Earth’s mantle – the asthenosphere – a layer of partly molten rock called magma. The lower part of the Earth’s mantle maintains a solid state as a result of the high pressure and reaches a depth of up to 2,900 kilometers. Beneath the mantle, all the way to the center lies the Earth’s core, which is made up mostly of iron. By their origin, rocks are classified as igneous, sedimentary and metamorphic. Igneous rocks make up about 95% of the lithosphere, whereas the other two types of rock are only 5% of the lithosphere.