Understanding the Interior of the Earth

• The Earth consists of several concentric layers, each nested within the other.
• The Crust – This is the topmost layer of the Earth’s surface.
• It is the thinnest among all the layers.
• It measures approximately 35 km on the continental masses and a mere 5 km on the ocean floors.
• The primary mineral constituents of the continental mass are silica and alumina, thus referred to as si-al (si for silica and al for alumina)
• The oceanic crust mainly comprises silica and magnesium, hence referred to as sima (si for silica and ma for magnesium)
• The Mantle – This layer is located just beneath the crust and extends up to a depth of 2900 km.
• The Core – This is the innermost layer with a radius of about 3500 km.
• It primarily consists of nickel and iron and is therefore known as nife (ni for nickel and fe for ferrous, i.e. iron).
• The central core experiences extremely high temperature and pressure.

A Study of Rocks and Minerals

• The Earth’s crust is composed of various types of rocks.
• A Rock is any natural mass of mineral matter that constitutes the Earth’s crust.
• There are three main types of rocks-
• Igneous rocks- these form when the molten magma cools and solidifies.
• Sedimentary rocks- these form when igneous rocks break down into small particles that are transported and deposited.
• Metamorphic rocks- these form when igneous and sedimentary rocks are subjected to heat and pressure, causing them to transform.
• Rocks are comprised of different minerals.
• Minerals are naturally occurring substances with certain physical properties and a definite chemical composition.
• Minerals hold significant importance to humankind. They are used as fuels, for instance, coal, natural gas, and petroleum. They are also used in industries to produce iron, aluminium, gold, uranium, etc., in medicine, in fertilisers, among other uses.

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