topic 1 - planet earth

what is the shape of the earth?

oblate spheroid

what is the mean diameter of the earth?

13,000km

recall the layers of the earth as well as details

atmosphere - nitrogen and oxygen

crust - very thin (relatively) - 30km, solid - low density rock

mantle - ≈80% of earth’s volume, lower; solid/upper; semi-molten

outer core - liquid iron and nickel

inner core - solid iron

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why is the crust split into tectonic plates?

the two states o9f matter within the mantle allow thermal convection currents to rise and fall, driving the sideways motions of the tectonic plates