Structure of the Earth
Rock
types
IgneousThese rocks are volcanic in origin Random
interlocking of crystals of different materials during the cooling.
Intrusive: Slow cooling
(within the Earth's crust) gives large crystals which are easy to seen – granite
Extrusive:
Rapid cooling (from volcanoes) – small crystals which can be seen under a microscope –
(extrusive rock) basalt. Pumice – gas trapped in the rock during solidification – low
density.
Igneous rocks are - Hard, have no fossils, have an interlocking crystal
structure
Sedimentary This type of rock is deposited as fine
particles from ancient seas. Layers.
The rocks are then formed by compression to give
various types such as chalk, limestone, sandstone and mudstone.
Rocks made of large
sized particles (pebbles) are called conglomerates (sometimes called "pudding stone"
because it looks a bit like a pudding).
Inorganic – formed from particles or fragments of
rock
Organic – formed from shells and skeletons of tiny
organisms.
MetamorphicThese rocks are ones that have been
changed during their lifetime. These changes occurred because of the action of heat and
pressure on the rocks.
Heat only:
Limestone changes to marble
Heat and
pressure:
Mudstone (clay) changes to slate and schist. Slate can be split into sheets
(cleaved). This makes it very useful for roofing and is caused by the effects of pressure
during formation.
Greek: meta – change morphe - shape
Continental
drift Continental plates moved across the surface of the Earth. Caused the
buckling of the Earth's crust to form mountain ranges, for example when India collided with
Asia to give the Himalayas.
Further topics to be completed
Temperature within the Earth
Paleomagnetism – study of the
ancient magnetism of the Earth. The direction of the Earth's magnetic field has reversed
more than once in the past.
Erosion - ice, wind, water
Faults, folds, anticline,
syncline
The rock cycle
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