Jawaharlal Nehru Technological University Hyderabad B.Tech II GENERAL GEOLOGY Previous Question Paper (March - 2022 - R18)

The Earth is composed of distinct layers based on chemical composition and physical properties. Chemically, it is divided into the crust, mantle, and core.

The Crust is the outermost thin, brittle layer. It is divided into the continental crust, which is thicker and composed primarily of granitic rocks (silica and aluminum), and the oceanic crust, which is thinner and composed of denser basaltic rocks (silica and magnesium).

The Mantle lies beneath the crust and extends to a depth of about 2,900 km. It is composed of dense, iron- and magnesium-rich silicate rocks, primarily peridotite. It is divided into the upper mantle and lower mantle, characterized by high-temperature solid-state flow.

The Core is the innermost part, composed mainly of iron and nickel. It is divided into the liquid outer core and the solid inner core, which generates the Earth's magnetic field through convection currents.

The interior of the Earth is studied through seismic waves, revealing a layered structure based on mechanical behavior:

1. Lithosphere: The rigid, outermost shell comprising the crust and the uppermost solid mantle.
2. Asthenosphere: A plastic, semi-molten layer within the upper mantle that allows for tectonic plate movement.
3. Mesosphere: The solid, high-pressure lower mantle region.
4. Outer Core: A liquid layer of iron-nickel alloy responsible for the Earth's magnetic field.
5. Inner Core: A solid, extremely dense sphere of iron and nickel due to immense pressure.

Diagram description: Imagine a cross-section of the Earth as a sphere divided into concentric circles. The center is the solid inner core, surrounded by a thicker liquid outer core. Above this is the massive mantle, with the thin asthenosphere layer near the top, and finally, a very thin, outermost skin representing the crust/lithosphere.