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| Question | Answer |
| The 4 Terrestrial Planets | Mercury Venus Earth Mars |
| Where does the asteriod belt lie, what does it contain? | Betwen Mars and Jupiter Left over from the formation of the solar system Thought to be remains of planets that failed to form |
| The 4 gas giants | Jupiter Saturn Uranus Neptune |
| Formation of the solar system | Molecular cloud of gas and dust collapsed when it was hit by an exploding star (supernova) Material formed a rotating disc triggering a nuclear reaction forming the Sun Accreation formed the planets |
| Asteriods Meteorites Comets | Rocky objects which failed to form a planet Fragments of rock which fall to Earth from Space Made from dust and ice which turns into vapours when its close to the sun |
| Types of meteorites | IRON - alloy of Iron and nickel, thought to represent core of small planet like objects STONY - silicate minerals, thought to represent the mantle CARBONACEOUS CHONDRITES - type of stony, water anf organic compounds, similar in composition to the Sun |
| Impact craters cause... | Material to be ejected Quarts grains violently shocked Rock strata tilted Material brecciated Ejected material falls back to surface woth sequence of rocks inverted |
| Age of Earth and Solar System | 4550 million years |
| Method used to date rocks | Radiometric dating |
| Depths of layers of the Earth | Crust (0-35km) Upper mantle (35-700km) Lower Mantle (700-2900km) Outer core (2900-5100km) Inner core (5100-6400km) |
| State and composition of the layers lf the Earth | Upper mantle - Solid silicates, peridotite Lower mantle - Solid, silicate material Outer core - Liquid, iron and nickel Inner core - Solid due to extreme pressure, iron and nickel |
| Direct evidence for the structure of the Earth | Deep mines (5km) - have direct access to higher levels of the crust Boreholes (13km) - samples of rock and microfossils can be brought up Volcanoes - magma that feeds volcanoes originates in crust/upper mantle so carries up samples Kimberlite pipes Oophiolite suites - sections of oceanic crust that break off during collisions |
| Indirect evidence of Earth Structure | Seismic waves - p and s waves |
| P wave shadow zone | 103° - 142° Refracted by outer core at Gutenburg Still travel through the core at a slower speed |
| S wave shadow zone | 103° - 103° Refracted by outer core at Gutenberg Stopped at the core as S waves can't pas through because liquid has 0 rigidity S waves can still be generated in the core by P waves |
| Origin of Earth's magnetic field | Convecting mass of molten iron in the outer core will generate electricity and induce magnetism This is called the self exciting dynamo effect |
| Palaeomagnetism | Ancient magnetism preserved in rocks |
| Magnetic reversals | Fe rich magnetic minerals (magnetite) align with Earth's magnetic field and as they cool, retain this magnetism permanently Act like 'frozen compasses' showing direction to the poles at the time of their formation |
| Magnetic inclination | ANGLE OF DIP OF THE LINES OF A MAGNETIC FIELD Following the lines of the Earth's magnetic field, a freely suspended compass needle lies vertical at the poles. At the equator lines horizontal. We can measure the inclination of a rock to find its latitude when it formed |
| Remanent magnetism | Magnetism shown by rocks due to the alignement of their magnetic minerals according to the Earth's magnetic field at the time of their formation |
| Polar wandering curves | Some believed that the poles were moving (wandering) |
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