T3 Science Exam Revision Flashcards
Name the three compositional layers of the Earth
Crust, mantle, core
Name the five mechanical layers of the earth
Lithosphere, aesthenosphere, mesosphere, inner core and outer core
Describe the features of the lithosphere
- Made up of tectonic plates
- Rigid, breaks easily
- Located in the uppermost mantle and crust
Describe the features of the aesthenosphere
- Beneath the lithosphere
- Top part of the mantle
- Flowy, is the location of convection currents
Describe the features of the mesosphere
Composed of strong rocks that slowly deform due to intense heat and pressure, the mesosphere is located beneath the asthenosphere
Describe the features of the outer core
The outer core is beneath the mantle and surrounds the inner core. It is composed of liquid iron and nickel, and controls the Earth’s magnetic field
Describe the features of the inner core
The inner core is the centre of the Earth, and made of solid iron (primarily) and small amounts of nickel. Despite the intense heat, the inner core is solid due to the immense pressure.
What are the two types of crust?
Oceanic and continental
Compare and contrast oceanic and continental crusts
Continental:
- Less dense than oceanic crusts
- Made of granite
- 30-50KM thick
Oceanic:
- More dense than continental crusts -
- Approx 8KM thick
- Composed of dense rock, like basalt
- Slips beneath continental plates at converging boundaries- creating subduction zones
What is the theory of continental drift?
In 1912. German meteorologist Alfred Wegner proposed a new theory- the Continental Drift Theory- that suggested the continents were slowly drifting across the Earth over a weaker mantle, sometimes pushing through ocean crust and colliding with each other.
- he also proposed that Earth was once a supercontinent called Pangea
Name three key people in the development of the Continental Drift theory and describe their contribution
Antonio Snider-Pellegrini (1858)
- Proposed that the identical fossil plants in North America and Europe could be explained if they were once connected (Pangea)
Alfred Wegner (1912)
- Proposed the continental drift theory, supported by the fossil evidence
Harry Hess (1962)
- Discovered that new sea floor was being created at mid-ocean ridges
- This provided a driving force for the movement of the continets in the theory of Continental Drift
State the four main pieces of evidence Arthur Wegner used to support his continental drift theory
- The apparent fit of the continents - how they fit with each other
- Fossil correlation - identical fossils could be found in completely different locations which could be explained by Continental Drift
- Geologic structures - rock and mountain correlation - The matching up of similar rocks in different locations
- Paleoclimate data
- Evidence of glaciers - glacial striations
- Concluded that the continents were not always near the equator, but rather closer to the poles, where the climate allowed for glaciers to form, and therefore would have had to move over time
Who first proposed continental drift?
In 1596, Cartographer Abraham Ortelius was the first to point out the similarities between Africa and South America’s coastlines, suggesting they might have once been joined.
What is a mesosaurus?
A fresh water animal with fossils found in the southern tip of South America and Africa
Explain the process of sea floor spreading
Sea floor spreading is when magma breaks through a weaker part of the oceanic crust and rises, pushing the crust out of its way and cooling, creating new sea floor.
What is magnetic striping?
Magnetic striping shows the normal magnetic polarity and the reversed magnetic polarity that has occurred in the Earth over time
How does magnetic striping occur?
Magnetic striping occurs when the north pole becomes the south and vice versa. The stripes show this reversal and indicate that the youngest rock is next to the ridges and the oldest next to the trenches.
How does seafloor spreading support Wegner’s theory of Continental Drift?
Sea floor spreading explains how continents can drift apart. As new crust forms at the mid-ocean ridges and spreads outwards, it causes the continents to move away from each other. This process supports Wegener’s idea that continents were once joined together in a supercontinent (Pangaea) and have since drifted apart.
Where in the Earth’s crust do convection currents occur?
The mantle
Explain the process of convection currents
Convection currents occur in the mantle, which is made up of viscous molten rock that rises as the particles heat up and become less dense. Once these particles reach the lithosphere, they cool down, become more dense and drop back down, creating convection currents.
How do convection currents result in different types of movement at plate boundaries?
The powerful cycle of convection currents, once they reach the tectonic plates in the lithosphere, can slowly push the plate apart (diverging plate boundaries), or conversely, pushes plates together (convergent plate boundaries). .
How do you plot co-ordinates on a map?
Using the equator and the Prime Meridian, you find the latitude and longitude of a plate and line it up so both numbers match.
Define latitude
Latitude is how far north or south of the Equator a place is
Define longitude
Longitude is how far east or west of the Prime Meridian something is
What is a transform plate boundary?
A transform plate boundary is when two or more tectonic plates slide/grind against each other in opposite directions
What can happen at transform plate boundaries?
Feature formed:
Transform fault (basically a big break in the rock where the movement of the plates has occurred)
Activity that occurs as a result:
Earthquakes
What is an example of a transform fault?
The San Andreas fault in California
Define convergent plate boundaries
Converging plate boundaries (also called destructive plate boundaries) are where plates come together. There are three types of converging plate boundaries:
1. Oceanic - continental : the oceanic plate is pulled beneath the continental plate (this is called subduction)
2. Oceanic - oceanic
Continental - continental
What activities/features occur at convergent boundaries?
Oceanic- continental:
Trench and volcanoes, subduction zones
Oceanic-oceanic:
Oceanic trenches, underwater volcanoes, subduction zones
Continental-continental:
Mountain ranges
Is a convergent plate boundary constructive or destructive?
Destructive
Is a divergent plate boundary constructive or destructive?
Constructive
Explain how continental-continental converging plate boundaries result in mountain ranges
When the plates converge (meet together) they fold upwards and create mountain ranges (the mountains occur along the boundary where they have folded upwards, which is why there is more than one mountain created).
Explain how continental-oceanic converging plate boundaries result in trenches and volcanoes
When the plates collide, the denser plate (oceanic plate) subducts beneath the continental plate, which causes a trench. When the subducted plate falls beneath the crust and into the boiling hot mantle, it turns into molten rock and fuels a magma hotspot beneath the continental plate, eventually resulting in a volcano
Explain how oceanic- oceanic converging plate boundaries result in underwater trenches and volcanoes
Oceanic-oceanic convergent boundaries are the same as oceanic-continental, just all underwater.
(Subducted plate creates magma hotspot in the mantle beneath the crust, and trench is formed in the subduction zone)
Define divergent plate boundaries
When two plates pull apart, move away from each other. Has two sub types: oceanic and oceanic, continental and continental
Give an example of a convergent continental-continental geological feature
The Himalayas
Give an example of a divergent plate boundary
Sea floor spreading
- when the oceanic plates pull apart and magma from the mantle comes up, cooling into new sea floor
Define a fault line
A fault line is a fracture in the tectonic plates rock
What happens at a continental-continental divergent plate boundary
The two continental plates pull apart, creating a rift valley (big divots/rifts in the ground that eventually fill with water to create e.g. river)
What happens at an oceanic-oceanic divergent plate boundary?
The two oceanic plates pull apart in a process called sea floor spreading. Magma from the mantle beneath the tectonic plates rises up to fill the gap and eventually hardens, creating new sea floor
Define earthquake
an earthquake is the sudden violent shaking in the ground that is caused by the big release of energy from two tectonic plates shooting past each other
Define focus - also called hypocentre (in relation to an earthquake)
The point where the energy is released (always directly below the epicentre)
Define epicentre
The epicentre is the point DIRECTLY ABOVE the focus (or hypocentre)
Define seismic wave
Seismic waves are vibrations that travel through the Earth, usually caused by earthquakes or explosions. They help us understand what’s happening inside the Earth by measuring how these waves move and change.
Name the four main design strategies that can protect buildings against earthquakes
Base isolation
Dampers
Cross Bracing
Outrigger framing support
How does the feature of base isolation help to protect buildings from earthquakes
allow the building to move independently of the ground shaking beneath it
How does the feature of dampeners help to protect buildings from earthquakes
act like shock absorbers - dampening the motion of the building
How does the feature of cross bracing help to protect buildings from earthquakes
makes the building stronger and able to withstand the shaking motion
How does the feature of outrigger framing support help to protect buildings from earthquakes
improves the building strength by connecting the inner core or columns to outer columns.
- helps to support the building as it sways
Describe the relationship between earthquake activity and tsunamis
When two converging oceanic plates collide, the denser plate subducts beneath the other, simultaneously pushing the other plate up. When this plate shoots up, the energy and force pushes the water above it up as well, creating a huge wave and is a tsunami.
What plate boundaries do volcanoes most commonly form at?
CONVERGENT BOUNDARIES:
Oceanic-oceanic plate boundaries
Continental-oceanic plate boundaries
What type of convergent plate boundaries do volcanoes form at and how do they form?
OCEANIC - OCEANIC
CONTINENTAL - OCEANIC
When the denser of the two plates subducts beneath the other, it burns in the magma beneath the crust in a hotspot, which then erupts through the crust to eventually form volcanoes
Why are there no active volcanoes in Australia?
Because we are not at a plate boundary, and not near any convergent boundaries, volcanoes cannot form
Distinguish between lava and magma
Magma is the molten rock BENEATH the Earth’s surface, and becomes lava once it reaches the surface of the Earth
How do volcanoes form at mid-ocean rifts?
When the two plates pull apart, an opening is created for the magma to burst through and create a volcano
Describe the flow of lava during a volcanic eruption
Depending on its composition and temp, lava flow can be fluid or very sticky and viscous
How was the Great Dividing Range formed?
When NZ ripped away from Australia, the coast of Australia became really weak, allowing for magma to rise up through the crust and create a line of volcanoes. However, once the tectonic plates shifted, no magma was able to come up through the volcanoes and so they became mountains.
True/false: Australia has hundreds of dormant volcanoes
TRUE
Why does Australia have so many dormant volcanoes?
Because we are not on any plate boundaries, plates cannot collide and subduct, fuelling the magma chambers that would shoot upwards and cause the volcano to erupt
How was Uluru formed?
- Started as a big pile of sediment
- A great flood wet the sand and began to press down
- The pressure became so much the the grainy sand fused to solid sandstone
- 400 million years later, Uluru flips on its side
- Elements erode away the softer sandstone until the durable sandstone remained
How do igneous rocks form?
Igneous rocks form from the cooling and solidifying magma or lava
Name and compare the types of igneous rocks
EXTRUSIVE:
Forms on the earth’s surface, with small crystals. Formed from cooling lava.
INTRUSIVE:
Forms inside the volcano, in the magma chamber, has large crystals. Formed from cooling magma
Identify two types of extrusive igneous rocks
Basalt
Andesite
Identify two types of intrusive igneous rocks
Granite
Gabbro
What are granite and basalt rocks used for?
Construction - countertops, tile, building stones etc
Are basalt and granite igneous?
Yes
How are sedimentary rocks formed
These rocks are formed when erosion and deposition creates layers of sediments. Over time, more and more layers of sediments pile up and they are pushed together by compaction, eventually forming a rock.
Explain the Law of Superposition
This principle states that layers of rock are superimposed, or laid down one on top of another. The oldest rock strata will be on the bottom and the youngest at the top.
How does the Law of Superposition help geologists with their work?
By helping them to determine the relative ages of rock strata, or layers.
Name two sedimentary rocks
Sandstone (e.g. Uluru!!)
Limestone
How do metamorphic rocks form?
Metamorphic rocks are derived from igneous or sedimentary rocks that have changed their appearance or mineral composition due to the intense heat and pressure beneath the Earth’s surface.
What is an index fossil
Index fossils are fossils that help determine the age of other fossils and rock found in the same sedimentary layer
Define strata
Layers of sedimentary rock
Define deposition
When the sediments of weathered rock are transported by elements and settle all in one place
What are the 3 main types of weathering?
- Physical
- Chemical
- Biological
TRUE/FALSE
Extrusive igneous rocks have fine crystals
TRUE
What are the 2 types of physical weathering?
Exfoliation weathering (hot environments)
Freeze thaw weathering (cold - very cold - environments)
What is biological weathering?
the disintegration of rock due to the actions of organisms such as bacteria, plants and animals
What is exfoliation weathering?
Exfoliation weathering is the repeated heating and cooling of rock that causes the surface layers of the rock to flake off
What is freeze thaw weathering
Caused by the melting and freezing of water
What is EROSION
the action of surface processes such as water flow or wind, that remove weathered rock and transport it to another place
What is the name of a sedimentary rock with grains of all different sizes?
Conglomerate
What is an example of a sedimentary rock that is made up of mineral grains that can be easily seen and felt
Sandstone
What is an example of a sedimentary rock that is made up of mineral grains that CAN’T be easily SEEN but CAN be FELT
Siltstone
What is an example of a sedimentary rock that is made up of mineral grains that cannot be seen or felt
Mudstone
What are the textural and mineral features of FOLIATED metamorphic rocks?
- Obvious differences is grain sizes
- Layers and stripes
What are the textural and mineral features of UNFOLIATED metamorphic rocks?
- Hard to visually separate grain sizes
- Crystals and colours not organized
What are some features of metamorphic rocks in general?
- Have interlocking crystals
- Can have layers (foliation)
- Can be very dense
- Can have deformed fossils
What are the two types of metamorphism of rocks that occur in nature?
- Contact metamorphism
- Regional metamorphism
Describe contact metamorphism
When an existing rock comes into contact with really intense heat (e.g. lava/magma) and changes form (METAMORPHISM)
Describe regional metamorphism
- When an existing rock comes into contact with really intense pressure, which changes it into a metamorphic rock
- e.g. At a convergent plate boundary, when the two plates are pushing together, the rocks caught in the middle will engage in regional metamorphism
If you add heat and pressure to shale, what rock does it metamorphosize into?
Slate
If you add heat and pressure to slate, what rock does it metamorphosize into?
Schist
If you add heat and pressure to schist, what rock does it metamorphosize into?
Gneiss
Scale:
shale - slate - schist - gneiss
What is foliated rock?
A type of metamorphic rock that has distinct, repetitive layers
e.g. gneiss
What type of metamorphism causes foliation in the metamorphic rock?
Regional metamorphism
What is the key idea of the rock cycle
That rocks are continually changing from one type to the other and back again
- the cycle continues endlessly (with the help of geological processes)
What is the progression of rock types if the steps in the rock cycle are as follows? Melting and cooling → erosion and deposition → burial with increased temperature and pressure.
Igneous → sedimentary → metamorphic
Name the 7 MAJOR tectonic plates that make up the lithosphere
Pacific plate
Nazca plate
North American plate
African plate
Antartic plate
Indo-australian plate
Eurasian plate
REMEMBER: ANNAPEI
(African, Nazca, North (american), Antarctic, Pacific, Eurasian, Indo-australian)
define geological processes
geological processes are the natural processes that shape the physical makeup of the Earth
Do extrusive igneous rocks from from quickly or slowly cooling lava?
QUICKLY COOLING lava
Define minerals
Minerals are naturally occurring solid substances found in the earth’s crust. There are 2 types of minerals, metallic and non-metallic
What are ores?
Ores are minerals mined from the ground. They are what METALLIC MINERALS are called
What are the 5 characteristics that a mineral must have to be classified as a mineral
- naturally occurring
- solid at room temperature
- Inorganic - (this means it was not made from a living thing) e.g. seeds are made from trees (living things) but rocks are made from minerals which are NOT LIVING
- fixed chemical formula
- atoms are arranged in an orderly structure (crystalline)
Are rocks metallic or non-metallic minerals?
Non metallic
Name the 7 unique chemical and physical properties of minerals
- Class - the class is just the general ‘group’ or ‘type’ that the specific mineral or gemstone belongs to
- Composition - how the crystalline solid’s particles are arranged
- Hardness - the ability of the mineral to resist scratching or abrasion (its durability) - this can depend on the direction in which the mineral is scratched
- Fracture - when a crystal has split in an irregular fashion, creating a jagged edge or surface
- Cleavage - the tendency of a crystal to split along certain regular plains, leaving newly exposed faces that are flat and smooth.
- Lustre - the way of describing how light interacts with the surface of a mineral
- Streak - streak is the colour of a mineral that is left when it is dragged across a rough, white surface, usually unpolished porcelain.
What are the 3 defining characteristics of a rock
- Solid at room temperature
- Made up of mineral particles
- Developed by geological processes
What is the Mohs hardness scale?
A scale that ranks minerals on their ‘hardness’ (their ability to resist scratching)
True or false:
Diamond is the hardest mineral
TRUE
If fluorite can scratch calcite, but calcite cannot scratch fluorite, is fluorite harder or softer than calcite?
Harder
Name 3 examples of metamorphic rocks and list their common uses
Marble
* Construction and Architecture
* Sculpture
* Countertops
Quartzite
* Construction
* Decorative Stone
* Stone Tools
Gneiss
* Interior uses: Kitchen or bathroom countertops, decorative walls, flooring, and interior decoration.
Exterior uses: Garden decoration, paving stone, facades, and building stone.
Explain how you could show that calcite is harder than talc.
By attempting to scratch the talc with the calcite. If it scratches the talc, then calcite is harder
How can you identify if a volcano is due to a hotpot?
- If the volcano is not near any plate boundaries
- If there is a trail of volcanoes behind/in front of the volcano (this is because the plate on which the volcano/s are on is constantly moving in one direction over the stationary hotspot
Is oxidation an example of physical, chemical or biological weathering?
Chemical
Is plant roots growing in a crack in the rock and widening it an example of physical, chemical or biological weathering?
Biological
- because it involves the activity of a plant!
Where does magnetic striping occur?
Divergent plate boundaries
In longitude, how different are 180 degrees east from 180 degrees west, at the Equator?
Not different, they are the same
How do we classify rock types?
The process by which they are formed
If you are given pictures of rocks and don’t know what type, look for:
- Foliation (regional metamorphism)
- Strata (sedimentary)
- Crystals (igneous, intrusive)
What are the uses of sedimentary, metamorphic and igneous rocks?
Sedimentary rocks are often used in construction (like limestone for building) and as sources of valuable minerals and fossil fuels (like coal).
Metamorphic rocks are used for roofing materials (like slate), as decorative stones (like marble), and in sculpture.
Igneous rocks are commonly used for construction (like granite for countertops) and in making tools or statues.
What is a hotspot?
A super hot area of magma
Do continental - continental convergent boundaries result in earthquakes?
Yes, because these collision would release A LOT of energy, causing an earthquake
What is a hotspot, and how does it form volcanic islands?
A hotspot is a specific area of super hot magma that can burst through the crust above it. The lava then cools and over time forms a volcano. As the tectonic plate moves over the hotspot, a trail of volcanoes is created
e.g Hawaiin Islands
How can the age of rocks on the ocean floor provide evidence for plate tectonics?
The age of rocks on the ocean floor increases with distance from mid-ocean ridges. This pattern supports the idea that new crust is formed at ridges and spreads outward, confirming sea-floor spreading. This can be measured based on patterns of magnetic striping present in the rock.
What are the two most obvious fit of coastlines between the continents
South America and Africa
