The Restless Earth
A mindmap of the information in the Restless Earth topic. (See other mindmap for Case Studies)
- Created by: orangeee22
- Created on: 23-10-14 10:56
View mindmap
- AQA GCSE Geography: The Restless Earth
- 2. Plate Margins
- Destructive
- Earthquakes Happen
- Composite Volcanoes occur
- When two plates move towards each other
- If the plates are continental and oceanic, then the oceanic plates subducts underneath.
- If they are both continental, the plates are pushed upwards forming fold mountains
- Example: The Andes and Peru-Chile deep-sea trench in South America. There is the Nazca plate and the South American Plate
- Constructive
- Shield Volcanoes occur
- Earthquakes Happen
- When two plates move away from each other
- Example: The Mid- Atlantic ridge in the Atlantic Ocean. There is the Eurasian Plate and North American Plate
- Conservative
- No Volcanoes
- Earthquakes Happen
- Example: San Andreas Fault in California. There is the Pacific Plate and North American Plate
- Two plates move past each other
- Destructive
- 3. Landforms at Plate Margins
- Fold Mountains
- Example: The Andes in South America
- Formed at Destructive Plate margins when both plates are Continental
- Ocean Trenches
- Formed at Destructive Plate Margins where Oceanic and Continental Plates meet
- Formed in subduction zones. This is where the oceanic plate subducts beneath the continental plate, and this creates a large trench.
- Example: The Peru-Chile deep-sea Ocean Trench in South America
- Volcanoes
- Composite
- Found at Destructive Plate Margins
- Features
- Steep Sides and narrow base
- Made up of alternate layers of ash and larva
- Erupts rarely but violently- expelling steam, ash, larva and rock
- Sticky larva that doesn't flow very far. It's also acidic.
- Example: Mount Mayon in the Philippenes
- Shield
- Example: Mauna Loa in Hawaii
- Found at Constructive Plate Margins
- Features
- Wide Base and gently sloping sides
- Runny larva that flows a long way. it is also basic
- Frequent eruptions that aren't violent
- Composite
- Fold Mountains
- 1. The Earth's Structure
- Convection Currents
- Caused by heat rising from the Earth's core, which makes the magma move
- The magma moving causes the plates to move
- Structure
- Core
- Inner Core
- Centre of the Earth
- Solid
- Very hot, about 5500 degrees Celsius
- Outer Core
- Liquid iron and Nickel
- Inner Core
- Mantle
- Soft Molten rock
- About 3800 degrees Celsius
- Crust
- Thin, hard outer shell of the Earth
- Broken up into large pieces called Tectonic Plates
- Core
- Types of crust
- Oceanic
- 5-10km thick
- Dense
- Sinks when meets continental crust
- Oldest is only 180 million years old.
- What you get under oceans
- Continental
- 25-100km thick
- Less Dense
- Doesn't Sink
- Very old; 3- 4 billion years old
- What you get under land masses
- Oceanic
- Convection Currents
- 4.Super Volcanoes
- Features of eruption
- Ash shoots kilometers into the air
- Blocks out daylight over nearly all the continents, leading to mini ice ages and famines as food cannot be grown
- Ash settles over hundreds of Km2 burying field and buildings
- At least 1000km3 of material emitted
- Rock
- Ash
- Larva
- A thick cloud of 'super-heated' gas and ash will flow at high speed from the volcano, destroying everything within 10 miles.
- Ash shoots kilometers into the air
- Formation
- 1. Magma is blocked from reaching the Earth's Surface
- 2. Pressure begins to build up, more rock melts so more magma is formed. This creates a large magma chamber
- 3. When the pressure becomes to much, the entire surface above the chamber is blown away by a huge explosion. A caldera is formed.
- Example: Yellowstone in the USA
- Characteristics
- Flat
- Cover a large area
- Have a caldera- a large depression in the ground
- Features of eruption
- 5. Earthquakes
- Measuring Earthquakes
- Richter Scale
- Measures energy released
- Uses a seismometer
- Scale
- Unlimited
- Logarthmic, meaning that each degree is ten times as powerful as the one before it
- Mercalli scale
- Measures visible and felt effects of an earthquake
- Goes from 1 to 12, with 12 being total destruction
- (Uses Roman Numerals)
- Richter Scale
- Features
- The Focus is the point at which the earthquake actually happens (beneath the ground)
- The shallower the focus, the more damaging the earthquake on the surface
- The Epicentre is the point on the surface above the focus
- The closer to the epicentre, the worse the destruction
- Shock waves radiate out in all directions from the focus.
- The Focus is the point at which the earthquake actually happens (beneath the ground)
- Reasons for occurence
- At Constructive Plate Margins, friction builds up as both plates move over the mantle
- This friction is suddenly released when it becomes too strong, causing the plates to jerk past each other and shock waves to be emitted
- At Destructive Plate Margins, friction mounts when plates push at each other or when one slides underneath the other.
- At Conservative Plate Margins, friction mounts when the plates get stuck sliding past each other
- This friction is suddenly released when it becomes too strong, causing the plates to jerk past each other and shock waves to be emitted
- At Conservative Plate Margins, friction mounts when the plates get stuck sliding past each other
- At Destructive Plate Margins, friction mounts when plates push at each other or when one slides underneath the other.
- At Constructive Plate Margins, friction builds up as both plates move over the mantle
- Measuring Earthquakes
- 6. Tsunamis
- Occur when an earthquake happens with an epicentre on the seabed.
- This results in lots of displaced water travelling in all directions, including towards land.
- Occur when an earthquake happens with an epicentre on the seabed.
- 2. Plate Margins
- Shield Volcanoes occur
- At least 1000km3 of material emitted
- Rock
- Ash
- Larva
Comments
No comments have yet been made