Solar System

Structure of the Earth

The structure of the Earth consists of four layers. The inner core is made from a solid nickel/iron  alloy. The outer core is again made from the same metal but is liquid. Movement between the inner and outer core generates the Earth’s magnetic field. Between the core and surface is the mantle. The mantle is made from rock. Intense heat and pressure causes the mantle to act like a liquid. Convection currents in the mantle causes rocks to rise and fall like a lava lamp. The final layer at the surface is called the crust. The crust is very thin compared to the Earth’s diameter.

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Wegners Theory of Continental Drift

1911: Wegener’s theory of continental drift

Continents sit on large plates (called tectonic plates) made up of the Earth’s crust and upper sections of mantle. These plates float on the rest of the mantle. Heat from inside the Earth cause convection currents that caused the tectonic plates to move.

Evidence supporting Wegener’s Continental Drift theory

Radio processes (ongoing); The earth's core is radioactive and produces heat that reaches the surface through convection currents in the mantle

Earthquakes and Volcanoes (1940): If you plot occurrences of volcanoes and earthquakes they seem to build up in lines around the Earth

Rising Himalayas ( 1950/60)- The himalayan mountain range is rising between about 5 and 10 mm a year

Fit of the continents (1900)- The continents especially Africa and south America seem to fit together like a jigsaw

Rock types (1900) : Rocks of the same mineral content and age can be found directly opposite on widely separated continents

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Atmosphere

Similar planets to Earth have atmospheres high in CO2 and low in oxygen. It is likely that Earth’s atmosphere was similar

Gases from Volcanoes (Evidence 2):

Volcanoes produce a number of gases include CO2, NH3, and water vapour. As this is similar to atmospheres of other planets, it is likely that the early atmosphere was produced by volcanoes (after the hydrogen and helium had escaped Earth’s gravity). The ammonia would have broken down into the relatively stable nitrogen gas over the millennia

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Origin of the Earths Energy

Most of the Energy on Earth Originates from the Sun. Solar radiation is absorbed by the Earth's surface and transferred to the atmosphere. The Earth emits infrared radiation, some of which is absorbed and re-radiated by some gases in the atmosphere, creating a greenhouse effect.

The Balance between absorbed and emitted radiation results in a surface temperature that makes life possible.

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Origin of the Earth

Origin of the Earth

  • When new stars form they are surrounded by clouds of matter

  • The lighter elements tend to be ‘blown away’ by solar radiation/ winds leaving heavier elements (oxygen, aluminium, silicon and iron) closer to the star

  • The clouds spin and the atoms/ elements form compounds

  • The compounds clump together by gravity (accretion) to form planets

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