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The Earth's crust and upper part of the mantle are broken into large pieces called tectonic plates. These are
constantly moving at a few centimetres each year. Although this doesn't sound like very much, over millions of
years the movement allows whole continents to shift thousands of kilometres apart. This process is
called continental drift.
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· Second level
· Third level
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· Fifth level
The plates move because of convection currents in the Earth's mantle.
When the tectonic plates meet they can cause things such as
earthquakes and volcanos by pushing against each other or
*
going over /under each other. *…read more

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The theory of plate tectonics and continental drift was proposed at the beginning of the
last century by a German scientist, Alfred Wegener.
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Before to edit
Wegener Master text styles Wegener's theory
Before Wegener developed his theory, it was thought Wegener suggested that mountains were formed when
· Second
that mountains level
formed because the Earth was the edge of a drifting continent collided with another,
cooling down, and in doing so contracted. This was causing it to crumple and fold. For example, the
believed to form wrinkles, or mountains, in the Earth's Himalayas were formed when India came into contact
crust. · Third
If the level
idea was correct, however, mountains with Asia. It took more than 50 years for Wegener's
would be spread evenly over the Earth's surface. theory to be accepted. One of the reasons was that it
· Fourth level was difficult to work out how whole continents could
move: it was not until the 1960s that enough evidence
was discovered to support the theory fully.
· Fifth level
Earth around 200 million years The single landmass began to crack
ago, at
The positions of the
* the time of Pangaea and divide, due to the slow currents of *
magna beneath it continents today…read more

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two Master
main typestitle style
of tectonic plate
·Oceanic plates occur under the oceans
·Continental plates form the land
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Oceanic plates are denser than continental plates.
They are pushed down underneath continental plates if they meet.
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Magma· Third
(molten level
rock) is less dense than the crust. It can rise to the surface through
weaknesses in the crust, forming a volcano. Geologists study volcanoes to try to predict
future eruptions. Volcanoes can be very destructive, but some people choose to live near
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them because volcanic soil is very fertile.
· Fifth Thelevel
movement of tectonic plates can be sudden and disastrous, causing an
earthquake. It is difficult to predict exactly when and where an earthquake will happen,
even when a lot of data is available.
Earthquakes and volcanic eruptions happen at
*
the boundaries between plates. *…read more

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VEGTABLE OILS Vegetable oils are natural oils found in seeds,
nuts and some fruit. These oils can be extracted.
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The plant material is crushed and pressed to
squeeze the oil out. Olive oil is obtained this way.
Sometimes the oil is more difficult to extract and
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has to be dissolved in a solvent. Once the oil is
dissolved, the solvent is removed by distillation,
and impurities such as water are also removed,
· Second level to leave pure vegetable oil. Sunflower oil is
obtained in this way.
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· Fourth level Structure of vegetable oils
Molecules of vegetable oils consist of glycerol
· Fifth level and fatty acids. In the diagram below you can
see how three long chains of carbon atoms are
attached to a glycerol molecule to make one
molecule of vegetable oil.
* *…read more

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Vegetable oils in cooking
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Vegetable oils have higher boiling points than water. This means that foods can be cooked or fried at
higher temperatures than they can be cooked or boiled in water. Food cooked in vegetable oils:
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·cook faster than if they were boiled
·have different flavours than if they were boiled.
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However, vegetable oils are a source of energy in the diet. Food cooked in vegetable oils releases more
energy when it is eaten than food cooked in water. This can have an impact on our health. For example,
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people who eat a lot of fried food may become overweight.
· Fourth level Saturated and unsaturated fats and oils
· acids
The fatty Fifth level
in some vegetable oils are saturated: they only have single bonds between their carbon atoms.
Saturated oils tend to be solid at room temperature. Lard is an example of a saturated oil.
The fatty acids in some vegetable oils are unsaturated: they have double bonds between some of their carbon
atoms. Unsaturated oils tend to be liquid at room temperature, and are useful for frying food. They can be divided
into two categories:
·monounsaturated fats have one double bond in each fatty acid
·polyunsaturated fats have many double bonds.
Unsaturated fats are thought to be a healthier option in the diet than saturated fats.
* *…read more

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Comments

Eddie Murphy

some get me some popcorn im going to town on dis

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