The Structure of the EarthInternal Structure of the Earth
Answer Text: The Structure of the EarthInternal Structure of the Earth The evidence used to study the earth’s interior are 1. Mining 2. Drilling3. Quarrying/excavation A. Crust/Lithosphere • Outermost layer of the earth • Made of soils and other loose deposits of sand • The dominant rocks are granites. • Extends 0-50km • Has 2 layers 1. Sial • Also called continental crust • Made of light coloured rocks• Called sial because it’s made up of silica and aluminum. 2. Sima • Also called oceanic crust • Mainly made of basaltic rocks which are brittle. • Called sima because it is made of silica, magnesium and iron.Mohorovicic Discontinuity (Moho) •A definite zone of discontinuity between the crust and the mantle. • Was discovered by Dr. Andrija Mohorovicic in 1909. B. The Mantle/Asthenosphere • Layer lying between the crust and the core • Made of iron and magnesium • Has two layers1. Upper mantle • Rocks are more elastic than those of sima. • Temperature is about 1000◦c. 2. Lower mantle • Rocks are like very viscous liquid. • Temperature ranges between 1000◦c to 3000◦c.Why the Interior of Earth Is Very Hot a) Due radio-active decay causing most of the heating. b) Due to great pressure as a result of overlying crustal materials. c) The original heat resulting from slow cooling of the materials which were pulled off the sunGutenberg Discontinuity • A definite zone of discontinuity between mantle and core. C. Core/barysphere/Centrosphere • The innermost/central layer of the earth. • Has 2 layers Outer Core • Composed of very dense rocks• Made up of nickel and iron • Temperatures are up to 3700◦c. Inner Core • A solid mass of mainly iron • Temperatures are estimated to be 4500◦c to 5000◦c
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