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GCSE Geology Revision Check that you know the following words and understand all of the main ideas:

Book 1 - Earth Materials (RED)

Minerals: Do you know how to test the properties of minerals?

Cleavage Form Hardness (Moh’s scale) Streak

Lustre Density (how do you test it?)

Acid test (does it fizz with dilute hydrochloric acid)

Main minerals see below:

How do minerals form? * Hydrothermal – heat from magma dissolves

elements in water and as water cools (moving up through cracks) it leaves

crystals of metallic minerals behind in veins, Evaporites etc.

Rocks: Can you recognise rocks of the three main rock groups?

1) Igneous – crystalline rocks formed by the cooling of magma, they can

be intrusive forming plutons, sills and dykes or extrusive as lava, ash,

pyroclastic flows etc.

* Key point * Rapid cooling = small crystals (lava)

* Slow cooling = large crystals (pluton).

2) Metamorphic – formed by the altering of rocks due to heat and/or

pressure under the ground. They can be formed by contact

metamorphism (heat) or regional metamorphism (heat and pressure).

Key terms – metamorphic aureole, burial, foliation.

* Key point – Heat causes recrystallisation, pressure causes foliation *

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3) Sedimentary – formed by sediments being deposited by rivers, ice,

sea or the wind. These sediments have been eroded or weathered

and transported before formation. The rocks are deposited in layers

or beds. How are they formed and by what processes?

Key terms:

freeze thaw weathering – shattered, loose boulders,

chemical weathering – limestone to form limestone pavements

erosion – abrasion and attrition of particles to become rounded

sorting of particles to same size and shape with transport

* Key point – size of particles tells you energy of environment *

Only rock that breaks the rule are turbidites – all sizes together

Main rock types – Basalt, Granite, Peridotite, Andesite, Slate, Schist,

Metaquartzite, Marble, Breccia, Conglomerate, Sandstone, Shale, Coal and

Limestone.

* Do you know how these rocks are linked through the rock cycle*

Acidic rainfall dissolves limestone

along weaknesses (joints and bedding

planes). This slowly forms this

distinctive paving stone like feature

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Book 2 – Plate Tectonics and Hazards (YELLOW)

Structure:

Crust (oceanic and continental)

Structure of the Earth Lithosphere

Mantle (partial melt, convection)

Outer Core (Liquid, magnetism)

Inner Core (Solid, gravity, NiFe)

Tectonic Hazards: How are people affected by: (Earthquakes, volcanoes, tsunamis and landslides?)

How can the effects be managed?

The Three P’s – Prediction Protection Preparation

Learn the case studies

Mount Pinatubo 1991 Kobe Earthquake 1995

Haiti Earthquake 2010 Japan Tsunami 2011

Vargas Landslides 1999

Why do they happen? Where do they happen?

Plate Tectonics: Continental Drift – what is it and why is it happening?

Types of plate boundary:

a) Constructive (divergent) – sea floor spreading, basalt, pillow lavas,

partial melting, high heat flow, ocean ridge,

rift valley, shield (basaltic) volcanoes

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b) Destructive (convergent) - subduction, Benioff zone, epicentre, focus,

collision zone, island arc, andesitic magma

forming cone volcanoes, fold mountains.

Earthquakes range from shallow to deep.

c) Conservative – transform faults, earthquakes, San Andreas fault. Only

shallow earthquakes and no volcanoes.

*Can you draw diagrams of each of these types of plate boundary*

Can you recognise the plate boundaries on a map?

High heat flow from rising convection currents brings basaltic

magma to the surface. Shield volcanoes form and pillow lavas are

erupted under the sea creating new oceanic plates that spread

away from mid-ocean ridge.

The subducting plate drags with it

water that makes the magma andesitic

(gassy) as the plate melts. Explosive

(cone) volcanoes on the surface.

The subducting oceanic plate descends into

mantle and rubs against continental plate.

As it does, it creates a pattern of deeper

focus earthquakes (Benioff Zone).

B = _________________

Reasons why? _________

_____________________

_____________________

_____________________

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C = _________________

Reasons why? _________

_____________________

_____________________

_____________________

_____________________

D = _________________

Reasons why? _________

_____________________

_____________________

_____________________

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Book 3 – Planetary Geology (PINK) What are the main bodies in the solar system?

Objects from space: Asteroids

Meteoroids

Comets

Effects of impacts from space are positive and negative?

Better preserved on Mars/Moon than Earth – why?

Lunar rocks and features – impact evidence, volcanic/igneous

evidence (rocks are all igneous)

Martian rocks and features – impacts, igneous and volcanic rocks and

features, sedimentary features (evidence of water), wind-blown

(desert) features, evidence of ice

Book 4 - Geological Structures (GREEN) Do you know the main types of geological structures seen on maps, in the

field or on photos?

1) Horizontal / dipping rocks

2) Folding – Anticlines (up-folds), Synclines (down-folds)

3) Faults – Normal Reverse/Thrust Strike slip (horizontal movement)

4) Sedimentary structures – can be used to determine the way up of

rocks or where they were formed. * Mud cracks

* Cross bedding * Graded bedding * Ripple marks

5) Other features: Baked margins, cross cutting, included fragments

6) Unconformity (rocks don’t match either side of a boundary)

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7) Interpreting Block Diagrams:

Can you work out the geological

history from the clues? Cross cutting (dykes, plutons, faults),

Superposition (younger on top of older),

Unconformities, Folding and Faulting

8) Features on maps

Which of these represents the cross-section from F-G on the map above?

Can you recognise these on a map? Folds (anticline and syncline), Faults, Unconformities, Plutons, dykes, sills or lava flows

* Key rules

1) Rocks dip towards younger rocks

2) Younger features cut across older ones

3) Older rocks in middle of anticline, younger in middle of syncline

4) Rocks don’t match at an unconformity

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Book 5 - Earth History (ORANGE) – two books!

Earth History: ‘The present is the key to the past’

Relative dating: Comparing the ages of rocks and geological events.

a) Superposition – younger on top of older

b) Cross cutting – younger features cross cut older ones

c) Folding – older folded rocks below horizontal rocks

d) Unconformities – boundaries between young and old

e) Metamorphism – rocks heated are older

f) Fossils – Same fossils in rocks = same age

g) Sedimentary Structures (way-up structures) that allow us to

put layers of rock in order. Examples are mud cracks, graded

bedding, cross bedding, ripple marks.

Absolute dating - Using radioactive

decay of elements to give accurate

dates to igneous rocks. The Half-life

of an element is fixed and is the key.

Example uranium which decays to lead

over millions of years.

Fossils – Recognise them by number of hard parts or by their symmetry

1) Trilobites (three parts)

2) Dinosaurs

3) Corals – Septa (tropical seas)

4) Plants (coal swamps)

5) Trace Fossils – evidence of their life

Septa

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Suture lines became more complex over time from:

Goniatites – simplest

Ceratites – rounded

Ammonites - complex

* What are zone fossils and how are they used by geologists?

* Graptolites and Cephalopods as zone fossils.

6) Graptolites – Stipes, Theca

7) Cephalopods – Suture lines

* Five key features of zone fossils lived all over the world, large numbers,

easily recognised, lived in the sea, evolved quickly

Geological Evolution of Britain: What do the

rocks tell us about Britain’s past geological

history and movement?

* Desert sandstones – North of Equator

* Limestone, Chalk and Corals – Tropical

* Breccia – Glaciers, mountains

* Overall northward movement

Exceptional Fossils: How do finds such as Archaeopteryx (reptile/bird)

and ‘Lucy’ (early human) help us unravel the past?

Extinctions: How and why do these happen? (Dinosaurs 65mya – meteorite

impact leaving a large crater and iridium deposits)

Climate change: Icehouse vs Greenhouse, causes of climate change (ice

melt, thermal expansion of oceans, albedo effect and carbon cycle. Human

climate change - evidence? What can we do? (CCS) – see blue book.

Simpler body plan over time

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Book 6 – Economic Geology (BLUE) 1) Main resources – How do we use Limestone, Haematite and Uraninite?

2) Prospecting for minerals – How are resources found?

Geophysical surveys – magnetic, gravity

Geochemical surveys – testing soil and river water

3) Oil and Natural Gas – How are they

formed, migrate and are trapped?

Formed in shale (source rock) from slow

heating and breakdown of plankton. Migrate

through permeable rocks until they are

trapped by an impermeable cap rock (shale,

halite) inside a porous and permeable rock

(sandstone)

The four types of trap

* Oil prospecting using:

Mapping

Seismic surveys

Drilling

* Production – oil rigs

* Environmental problems

Pollution, spills, CO2

* New technology

Shale gas, fracking

* Carbon capture and

storage (CCS)

Reserves vs Resources

4) Hydrogeology – Groundwater and aquifers (properties of rocks such as

sandstone – porosity and permeability), water table, the siting of dams

and reservoirs.

5) Landfill Sites – Burial of waste, solving environmental problems of

leachate, noise and visual pollution. Where to site a landfill and what to

use them for after closure? What to do with Radioactive Waste?

The proven amounts of oil or minerals that

can be extracted at a profit. The unproven amounts of oil or minerals or

ones which cannot be extracted at a profit – yet!

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Practical Skills – Paper 2 Rock Texture: This is described from hand specimens or

micrographs using the three S’s. Always refer to Size, Shape

and Sorting of the particles making up the rock. Are they

crystals/grains, are they random or not?

Sedimentary Logs: These show a sequence of rocks from

oldest (bottom) to youngest (top). They are used to interpret the

change in environments over time. Remember that the further to

the right a rock goes the larger the particles inside it are. You

may be asked to complete one of these.

Dip and Strike: This is a way of recording how layers (beds)

of rock have been folded/tilted by compression. Dip is the angle

at which the bed is tilted and strike is the horizontal line across

the surface (bedding plane) of the rocks layer.

Maps and Cross-Sections: These are two ways of

showing geological information about layers of rock

underground. One is from above (map) and the other is

from a sideways/slice view into the ground (cross-section).

Measuring Directional Information: Rose diagrams

can be used to display and interpret any directional

information such as:

Wind (desert sediments)

Lava/magma flowing (crystals)

Alignment of fossils

Strike of beds

Testing Minerals: Minerals can be tested using a variety of

methods such as density, reaction to acid (dilute HCl), hardness, streak and cleavage.

*Remember you always have the date sheet with the ten main minerals to help you.

Sketching and Scale: You will be asked to

draw a scaled sketch of a feature and to label the

main geological features. Always include scale and

look to draw the key feature shown.