5.2. ENDOGENIC PROCESSES

The energy emanating from within the earth is the main force behind endogenic geomorphic processes. This energy is mostly generated by radioactivity, rotational and tidal friction and primordial heat from the origin of the earth.

Endogenic processes are driven by energy that originates from inside the Earth. This energy comes from several sources: radioactivity (the decay of radioactive elements), rotational frictions (the movement of Earth itself), and tidal friction (the gravitational pull of the moon and sun). Primordial heat refers to the heat from when the Earth was formed. All these factors together create movements and changes in the Earth's crust, leading to various geological phenomena.

Think of the Earth like a pressure cooker. The heat inside causes pressure to build up, creating steam. Similarly, the heat generated by the Earth's core causes internal pressure, leading to events like earthquakes and volcanic eruptions.

All processes that move, elevate or build up portions of the earth’s crust come under diastrophism. They include: (i) orogenic processes involving mountain building through severe folding and affecting long and narrow belts of the earth’s crust; (ii) epeirogenic processes involving uplift or warping of large parts of the earth’s crust; (iii) earthquakes involving local relatively minor movements; (iv) plate tectonics involving horizontal movements of crustal plates.

Diastrophism refers to processes that deform the Earth's crust. There are several key processes here:

1. Orogenic processes - These lead to the formation of mountains through folding of the crust.
2. Epeirogenic processes - These cause large areas of the crust to uplift or warp, affecting broad regions rather than specific mountain ranges.
3. Earthquakes - These are sudden movements of the crust that occur over small areas but can have significant effects.
4. Plate tectonics - This involves the movement of the Earth's tectonic plates, which can lead to various geological features and events.p

Imagine stretching and compressing a rubber band. Just like how the rubber band moves in different ways when you pull, push, or release it, the Earth's crust moves due to the forces acting upon it, causing mountains to rise and earthquakes to happen.

Volcanism includes the movement of molten rock (magma) onto or toward the earth’s surface and also formation of many intrusive and extrusive volcanic forms. Many aspects of volcanism have already been dealt in detail under volcanoes in the Unit II and under igneous rocks in the preceding chapter in this unit.

Volcanism is the process through which magma from the Earth's interior reaches the surface. This can happen in two ways:

1. Intrusive volcanism - where magma cools and solidifies beneath the Earth's surface.
2. Extrusive volcanism - where magma erupts onto the surface as lava, which can then form various volcanic structures. The study of volcanism encompasses both the activity of volcanoes and the rocks that result from these processes.

Imagine a soda bottle that has been shaken. When you open it, the pressure causes soda to spew out explosively. Similarly, when pressure builds up in a volcano, it can lead to a volcanic eruption where molten rock bursts forth from the Earth.

Due to variations in geothermal gradients and heat flow from within, crustal thickness and strength, the action of endogenic forces are not uniform and hence the tectonically controlled original crustal surface is uneven.

The Earth's crust is not uniform due to the varying internal temperatures and pressures. Different areas experience different amounts of heat and stress which leads to thick or thin sections in the crust. Consequently, this unevenness influences how landforms develop and change over time.

Consider a patch of dough that you press unevenly; some parts may be thick while others are thin. Similarly, the uneven pressure from the Earth's inner layers creates varying crustal thickness, leading to the diverse landscapes we see on Earth.

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