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The Earth: A Vibrant Planet. Sorry to break it to you but the earth is NOT round – rather a spheroid. It bulges at the equator and flattens at the poles…. Structure of the Earth. Earth: From Core to Crust. THE STRUCTURE OF THE EARTH:. CRUST – earth’s exposed rock
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The Earth: A Vibrant Planet Sorry to break it to you but the earth is NOT round – rather a spheroid. It bulges at the equator and flattens at the poles…
THE STRUCTURE OF THE EARTH: • CRUST – earth’s exposed rock • MOHO the separation between the crust and the asthenosphere • ASTHENOSPHERE – Plastic like substance – responsible for movement of earth’s crust. • MANTLE (MESOSPHERE) a semi-liquid plastic consistency which liquefies when pressure is reduced • OUTER CORE liquid • INNER CORE solid
Heating of the Earth causes convection currents in the Mantle
We know the structure of the earth due to the study of SEISMOLOGY (the study of earthquake waves) • the branch of geology that studies • earthquakes • Primary (P) waves and Secondary • (S) waves pass through the internal • layers of the planet
Primary Waves • P waves stretch and squeeze; moving quickly, can pass through any material • Travel by compression through solids, liquids, and gases • Speed up through the mantle • Drop at the outer core (liquid) • Speed up at the inner core (solid)
Secondary Waves • S waves vibrate passing only through solids • Slower than the P wave (60% of the speed) • Will NOT travel through liquid • Speeds up gradually through the mantle • Then stops at outer core
The use of “indirect evidence” serves to tell us the structure of the earth. Refraction and Shadow zones and arrival times are crucial
Our Vibrant Earth A Sombrio Production