Download Geological Processes class Booklet

GEOLOGICAL PROCESSES
Has Britain always been in the same place on Earth?
What causes Earthquakes and Volcanoes?
How do scientists come up with new ideas to explain
what they observe?
When do their ideas become accepted by other
scientists?
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Class
Date
Teacher
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CORE BOOKLET 10
This is the end of the core Chemistry course.
Other booklets in this course are 1, 2, 3, 4, 5,
6,7,8a,8b and 9. Good luck with your exam!
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GEOLOGICAL PROCESSES
Tick
You should:
Use the development of the theory of continental drift
to display their understanding that observations,
through creative thought, lead to an idea to explain
them but the explanation may not be accepted until
sufficient evidence exists, as follows:
 In 1915, Alfred Wegener suggested that the
Earth’s continents were once joined and had
moved apart to their present positions
 He based his idea on the close fit of coastlines,
and the similar patterns of rocks and fossils, of
continents separated by large oceans
 He was unable to convincingly explain how the
continents could move
 The current theory of plate tectonics became
widely accepted in the 1960’s, by which time
other scientists had found evidence to show that
it is the Earth’s plates that move and that they
do so as a result of convection currents in the
mantle.
Use evidence about the location of earthquakes and
volcanoes to appreciate that the Earth’s lithosphere is
composed of a number of large pieces called plates,
which are moving very slowly, and know that this
movement drives the rock cycle
Know that rocks can be:
 Formed where tectonic plates move apart and
magma rises to fill the gap producing new igneous
rock
 Deformed and/or recycled where tectonic plates
move towards each other driving down the denser
plate which may melt to form magma that on
cooling forms igneous rock
Summary Sheet
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The theory of plate tectonics
The outer layer of the Earth’s crust – the Lithosphere is not a continuous
structure but is split a little like the cracked shell on a hard boiled egg:
The result is a series of plates floating on the hot mantle beneath. Heat
in the mantle creates convection currents that cause the plates to move.
Plate margins exist where the plates meet.
The history of the Earth’s plates – see also
http://tanasi.gg.utk.edu/courses/101/public/BBC/default.html
The beginning of time
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Map – plates and continents of the World – today.
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Plate Margins – where plates meet
Earthquakes and volcanoes (evidence of unrest in the Earth), help locate
the edges of plates known as plate margins or boundaries.
Take for example the ‘Ring of Fire’ around the Pacific. Volcano’s can be
joined together using a ‘dot to dot’ technique. The pattern that follows
exactly matches known plate margins.
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Different types of plate margin and how they contribute to the
formation and deformation of rocks.
As plates move; they can push together or move apart.
1.
Moving apart – CONSTRUCTIVE, e.g. Atlantic mid-ocean
ridge.
The floor of the Atlantic Ocean is widening as plates are moving apart.
As magma gradually rises and cools between plates new rock called
igneous rock is formed.
Formation and uses of Igneous Rocks
The word igneous means fire. Igneous rocks are formed directly from magma as it cools.
The type of igneous rock depends upon the speed at which magma cools.
Slow cooling – intrusive igneous rock
Igneous rocks such as granite are formed when magma finds weaknesses and intrudes into the
crust. As it does so it cools and solidifies slowly below the Earth’s surface. This process often
occurs during plate tectonic activity; either when plates push together or move apart. Granite
only appears when rock above has been worn away; it is younger than the rock that surrounds it.
Igneous rocks such as granite can take hundreds of years to form. Granite is a very hard rock
used in building and road making.
Fast cooling – extrusive igneous rock
Igneous rocks such as basalt or obsidian are formed when magma erupts from a volcano as lava
and cools on reaching the surface. Basalt cools and solidifies quickly over a number of days.
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Appearance of Igneous Rocks

This is the intrusive igneous rock
GRANITE.

Granite take hundreds of years to form

It is made up of RANDOM,
INTERLOCKING crystals.

There are no bands, swirls or fossils
present
Intrusive igneous rocks

This is the extrusive igneous rock
OBSIDIAN

Obsidian takes days/weeks to form

It contains small/no crystals

There are no bands, swirls or fossils
present

intrusive igneous rocks such as
pumice contain lots of air pockets
2. Pushing together
Extrusive igneous rocks
- destructive e.g the Andes and Himalayas
In the above diagram the continental crust is pushing harder than the
lighter oceanic crust. This is similar to the plate margin responsible
for the Asian tsunami.
On the left of the diagram the oceanic crust or plate is being forced
under the continental plate. This is called subduction. Rock at the
bottom of the oceanic plate is re-melted. This is called deformation.
Meanwhile as the continental crust is forced upwards, magma also
moves upwards and cools forming new rock. This is called uplift.
Mountains/igneous rock are formed in this way.
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The Rock Cycle
Together deformation and mountain formation form part of the rock
cycle.
During this cycle rock is constantly being created and
destroyed.
Wegener and the theory of plate tectonics.
Utter, damned rot!" said the president of the prestigious American Philosophical
Society.
"If we are to believe this hypothesis, we must forget everything we have learned in
the last 70 years and start all over again," said another American scientist.
Anyone who "valued his reputation for scientific sanity" would never dare support
such a theory, said a British geologist.
All this was said of Alfred Wegener’s
theory in 1915 that the crust was not one continuous land mass
but was divided into plates. He also proposed that the Earth’s
continents had once all been part of one large super continent
which he called Pangaea. Wegener based this on several pieces
of evidence;
1. Wegener noticed that despite being separated by an
ocean, South America and South Africa look as though
they could fit together like pieces of a jigsaw puzzle.
2. Fossils of plants and animals from different sides of the
Atlantic were the same.
3. Rock strata in North America and the Scottish Highlands
appeared to match.
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Wegener’s theory that continents making up Pangaea had
drifted wasn’t accepted until two Cambridge University
scientists found further evidence in the 1960’s from looking
at magnetic field patterns at the bottom of the Atlantic
Ocean. Wegener died at 50 on a rescue exhibition to
Greenland.
END OF SUMMARY SHEETS
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Convection Currents – see worksheet
Describe what you did and write/draw your
observations.
1.
Describe what you did and write/draw
your observations.
2.
3. Describe/draw and label what happened when the two
bottles were placed on top of one another.
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4. What causes the Earth’s plates to move –
answer this question
fully, use the worksheet to help you.
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5. Draw a diagram to represent convection currents in
magma.
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ASSESSMENT
INTRODUCTION
If, on the Sunday morning after Christmas 2004, you had been like
some all-seeing, all-knowing deity, able to peer down through the
ocean depths off the western coast of the island of Sumatra, here is
what you would have seen:
Two giant tectonic plates, which have been pushing against
each other for millennia, suddenly shift.
The left plate has been sliding under the right at the rate of a
few centimetres a year, but now the top plate suddenly springs
up, lifting perhaps 60 feet along a 1,000-mile ridge. Above,
the ocean surface hardly ripples.
The quake jolted the Earth's rotation enough to trim a couple of
microseconds off the clock. Relatively speaking, it was a small blip in
the long, violent history of a planet with a molten core, where entire
continents have vanished and then reformed. But the seismic bump
was enough to displace trillions of tons of water in a few seconds.
Silently, invisibly, the water pushed outward at the speed of a jet
plane. As it neared shore, the speed slowed, and large waves formed,
in some places very large ones.
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What caused the Asian Tsunami on
Boxing Day 2004?
Gra
de
What to include to achieve grade
G
An introduction to the theory of plate tectonics including a
diagram/map of the Earth’s plates.
An explanation of the history behind the theory of plate tectonics
including a mention of Wegener and of the two Cambridge scientists.
An explanation of the evidence for plate tectonics at least 5 pieces
(3 from Wegener, 1 from the Cambridge scientists and 1 link between
volcanos /earthquakes and plate margins)
An explanation of continental drift use Britain as an example of a
country that has drifted.
An explanation of convection currents.
Explain what happens at the two types of plate margin destructive
and constructive (use diagrams). Explain how they contribute to the
formation and deformation of rocks (the rock cycle).
Make links between the theory of plate tectonics and the Asian
Tsunami.
Talk about other examples of the effects of plate tectonics.
F
E
D
C
B
A
A*
You are encouraged to research and bring in your own resources from
home on this topic. Present your assessment on A3 paper. You can stick
in photographs. You can use the internet there are tonnes of excellent
websites on Geology. Please summarise any researched information and
present it in your own words. Large, bright presentation please!
Key skill – I.C.T
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