Magmatic Evolution and Differentiation: Fractional Crystallization --- ## **Magmatic Evolution** * The process by which a **parent magma** changes its composition during cooling, crystallization, and interaction with rocks. * Leads to the...

Magma – Nature, Types, Composition and Generation --- ## **Nature of Magma** * Magma is a **naturally occurring molten rock material**, generated within the Earth’s crust or upper mantle. * It is a **complex, multicomponent...

Concept of Stress and Strain Stress * Stress is the **force per unit area** acting on a rock body. * Formula: sigma ={F}/{A}     where $F$ = force, $A$ = area. * Types of stress:   1. **Normal stress ($\sigma_n$)**...

Structure and Origin of the Alpine–Himalayan Belt and Evolution of the Indo–Gangetic Basin 1. Structure and Origin of the Alpine–Himalayan Belt** ### **Origin** * The **Alpine–Himalayan Belt** is the world’s...

Concept of Continental Drift, Sea-floor Spreading and Theory of Plate Tectonics 1. Continental Drift (Proposed by Alfred Wegener, 1912) * The **Continental Drift Hypothesis** states that continents were once joined together in a single...

Concept of Orogeny Orogeny refers to the large-scale structural deformation of the Earth’s lithosphere leading to the formation of mountains. The term is derived from the Greek words *oros* (mountain) and *genesis* (origin). Orogenic...

🌋 Magma Nature of Magma Magma is a molten or partially molten, naturally occurring silicate material beneath the Earth’s surface. It consists of: Liquid phase → molten silicate melt. Solid phase → crystals of early-formed...

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Mountains – Types, Characteristics, and Origin 🔹 Definition: Mountains are natural elevations of the Earth's surface that rise prominently above the surrounding terrain. They are formed due to tectonic forces, volcanic activity, or...

Island Arcs – Curved Chains of Volcanic Islands 🔹 Definition: An island arc is a curved chain of volcanic islands that forms along a subduction zone, where an oceanic plate sinks beneath another oceanic plate. This process results in...