Geology

Property - Colour

Is a guide to identifying - not reliable because impurities, can be same colour, same mineral can be different colours

Property - Hardness

Is a measure of a rocks ability to scratch other minerals, Mohs scale measures hardness

Property -  Lustre

Shininess of a material, can be earthy, vitreous, brilliant, pearly, metallic

Property - Streak

Colour of minerals powdered form - not always the same as mineral
To get powder mineral is rubbed against hard surface

Property - Cleavage/Fracture

Is how a mineral break up into pieces - thin sheets, small pieces

What is a mineral

Chemicals (elements or compounds) that occur naturally in the Earth’s crust. They are the basic building blocks of rocks. 

Criteria to be Mineral

Solid - at normal temp
Naturally occurring - occur in nature, not lab
Inorganic - Don’t come from living things
Fixed chemical structure - will always have the same formula
Crystal Structure - repeating arrangement of atoms

Mohs Hardness Scale

The higher on the scale the harder it is. The lowest can have everything above it scratch it, but the highest thing can’t have anything below it scratch it.

Igneous Rock

Rocks that form from the cooling of lava or magma

Extrusive Igneous Rocks

Cool quickly and as a result these rocks are fine grained or has lack of crystal growth.

Intrusive Igneous Rocks

Formed from magma that cools slowly and as a result these rocks are coarse graine

Sedimentary Rocks

They are compacted sediment

Lava

molten rock at or above earths surface

Magma

is molten rock below the earths surface

Weathering

Breaking down of rock

Erosion 

is the moving of that rock/sediments

How are sedimentary rocks formed

Sediments are deposited in layers
The grains of lower layers begin being forced together
Chemicals that are dissolved in the water can soak into the sediments
The chemicals help cement the grains together once the water has evaporated 

Sedimentary Type - Biological

Are formed when the remains of living things break down and are deposited as sediments

Sedimentary Type - Chemical

Are formed when water evaporates, leaving behind a solid substance

Metamorphic Rocks

Are rocks formed when other types of rocks are changed by heat and pressure inside the Earth

Metamorphic Rock Uses

they can be used for building materials

Metamorphic compared to parent rock

Metamorphic rocks, their crystals can become bigger, change shape, new texture and appearance, their chemicals can change

The Rock cycle

Rocks can and will change over time due to pressure, weathering, compaction and cementation, erosion or temp changes

Body Fossils

are the fossils of bones, teeth, and shells

Trace Fossils

are rocks that have preserved evidence of biological activity

How fossils are made

Animal dies
Soft parts rot away or eaten
Before body rots away, buried by sediment
More layers build, putting weight and pressure, making them sedimentary rock
Water seeps into bone and teeth, turning them to stone as it leaves behind minerals

Fossils

are remains and traces of organisms preserved in rocks

Relative dating

Does not give exact age, compares with ages of other things, (older or younger)

Absolute Dating

Actual number of years

Cast fossil

a fossilized copy of an organism, formed when an impression, or mold fossil, is filled with minerals or sediment

Mould Fossil

An empty space left in a rock after an organism’s remains have dissolved

Why are fossils found in sedimentary rocks

because of the process of their formation

Convection Currents

drive movement of magma through mantle which causes tectonic plates to shift

Continental drift

the idea that the continents are continually moving and were once joined together to form a supercontinent called Pangaea

Sea-floor spreading

This theory says that the middle of the ocean is spreading apart because tectonic plates are moving very slowly in opposite directions

How many major plates are there

12

Movement because of heat energy

convection currents in the earths mantle which are driven by heat energy from the earths

Divergent boundaries

are where plates move away from each other

Convergent boundaries

are where the plates move towards each other

Transform boundaries

are where the plates slide past each other

Crust

thinnest layer
between 5-70km thick
temp between 20-500C
thinner under oceans

Mantle

2900 km thick (thickest layer)
Temp between 500-2000C
Made of solid rock that flows
Moves in big circles called convection currents

Outer core

2300km thick
temp 3000C
made of mainly iron and nickel
is liquid
generates magnetic field

Inner core

1200 km thick
temp 4000C
Metals are solid
made of iron

Rock cycle

magma - cool -igneous rock - weathering erosion - sediment - compacting and cementing - sedimentary rock - heat and pressure - metamorphic rock