Paper I · 4 Geography of India & AP · APPSC Paper I
4.1.2 Interior of the Earth and plate tectonics notes
9 notes, in reading order.
- 4.1.2.1Interior of the Earth: crust, mantle, core and discontinuities
The Earth is layered like an onion: a thin rocky crust, a thick solid but slowly flowing mantle, and an iron–nickel core whose outer part is liquid and inner part solid; we know this mostly from indirect evidence, above all seismic waves.
Standard · 8 min · Full course - 4.1.2.2Seismic waves: P, S and surface waves and shadow zones
An earthquake sends out body waves (P and S) that travel through the Earth and surface waves that travel along it; the way these waves speed up, bend and disappear in shadow zones tells us the layered structure of the interior.
Standard · 7 min · Full course - 4.1.2.3Continental drift theory: Wegener's evidence and its limits
In 1912 Alfred Wegener argued that all continents were once joined in one supercontinent, Pangaea, which broke up and drifted apart; his evidence was strong but the forces he proposed were too weak, so the idea was accepted only after sea-floor spreading and plate tectonics supplied a mechanism.
Standard · 7 min · Full course - 4.1.2.4Sea-floor spreading and palaeomagnetism
Harry Hess proposed in the early 1960s that new ocean floor forms at mid-oceanic ridges and is consumed at trenches; the matching magnetic stripes on both sides of the ridges, recorded as the Earth's field reversed, proved it and supplied the mechanism Wegener lacked.
Standard · 7 min · Full course - 4.1.2.5Plate tectonics: major plates and divergent, convergent and transform boundaries
The lithosphere is broken into seven major and several minor rigid plates that move over the asthenosphere; where they pull apart, collide or slide past each other we get ridges, trenches, fold mountains, earthquakes and volcanoes.
Standard · 9 min · Full course - 4.1.2.6Earthquakes: focus, epicentre, magnitude and intensity scales and world belts
An earthquake is the shaking of the Earth when energy stored in rocks is suddenly released, usually by slip along a fault; its size is measured by magnitude (energy) and its effect by intensity (damage), and most earthquakes occur along plate boundaries.
Standard · 9 min · Full course - 4.1.2.7Tsunamis: how they form and early warning systems
A tsunami is a series of very long sea waves set off by a sudden vertical shift of the sea floor, usually an undersea earthquake; harmless-looking in the open ocean, it slows and towers up near the coast, so warning depends on detecting the earthquake and the wave within minutes.
Standard · 9 min · Full course - 4.1.2.8Volcanoes: types, volcanic landforms and the Pacific Ring of Fire
A volcano is a vent through which molten rock, gases and fragments reach the surface; the type of eruption and landform depends on how fluid the lava is, and most active volcanoes sit on plate boundaries, especially the Pacific Ring of Fire.
Standard · 8 min · Full course - 4.1.2.9Diastrophism: folding, faulting and mountain building
Diastrophism covers all the processes that move, lift or build up parts of the Earth's crust, such as folding, faulting, uplift and mountain building; driven by the Earth's internal heat, it raises the relief that exogenic forces then wear down.
Standard · 8 min · Full course
Practise Interior of the Earth and plate tectonics. Questions with answers explained, from the same topics.
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