Rocks
Minerals and Rocks
• Rocks are mixtures of different minerals
Grains in rock
Rocks are made up of grains and they can absorb water.
It is described as porous.
Structure of Earth
Lava and Magma
Igneous rocks
• When molten rock cools down, it will slowly turn into igneous rocks.
• 2 types of Igneous Rock
• Intrusive – Forms underneath the ground
• Extrusive – Forms above the ground
Formation of Igneous
• The particles arrangement depends on how fast it cools down.
• If it cools down fast, there is not enough time for the particles to form a
crystal.
Weathering
• When igneous breaks down into smaller pieces, they turn into
sediments.
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There are 3 types of weathering
A) Chemical
B) Biological
C) Physical
Chemical Weathering
When rain falls onto rocks, the rain react with rocks and dissolve
them. This reduces the size of the rock
Biological Weathering
• When plants grow inside the cracks, it can make the cracks
larger and thus breaking the rock.
Physical Weathering
• There are 2 types of physical weathering
• Onion skin
• Freeze-thaw action
Onion-skin weathering
Freeze-Thaw Weathering
Erosion
• When rocks are broken down after weathering process
• They get moved away from place where they were found.
• This is called erosion
Abrasion
• As the rocks are moved around by the water, the rocks
fragments hit each other and break.
• The bits of rocks and sand in river is called sediment.
Sedimentary Rock
• Small rocks deposit into layers.
• They are made from grains and not
• Interlocking crystals
Rock Cycle
Materials in the Earth
• Some minerals are found as pure elements in rocks. They are in their native
state.
• Rocks that can contain many metals are called ore (obtained through mining)
Pollution
• Mining can damage the environment by destroying the
habitats and causing pollution.
Modern Devices
• Many devices need small quantities of rare metal.
• These metals are hard to find and can be found at certain places.
Recycling
• Recycling is converting waste into a useful materials
Advantages of Recycling
• Recycling is better than making things from scratch because
• Use lesser amount of Earth’s resource
• It uses lesser energy
• Recycling saves more money
• Make lesser amount of rubbish
• Eg – Recycling aluminum cans
Example of recycling
• Aluminum can
• If not recycled, more aluminum needs to be mined
• Mining cost more energy and money
• Aluminum needs to be extracted and transported which cause uses more energy and
money
• For 1 kg of aluminum can recycled, you save
• 95% of energy needed to mine and extract
• 4 kg of aluminum ore
Tectonic Plates
• large slabs that move over a liquid mantle. Mountains form and earthquakes
shake at tectonic plate boundaries, where new landforms rise and fall.
Earthquakes