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