Y9 - The Restless Earth Flashcards
What is the Inner most layer of the earth called?
The inner Core
What is the Inner Core?
The Hot, solid center of the earth.
What is the 2nd most inner layer of the earth called ?
Outer core
What is The Outer core?
The liquid layer surrounding the inner core. Mainly made of iron and nickel, this creates our magnetic field
What is the layer surrounding the outer core?
The mantle
What is the mantle
The thick layer of magma, the thickest layer.
What is the outer layer of the earth?
The Crust
What is the Crust?
A thin layer of solid rock making up the outer shell of the Earth. it is made up of large tectonic plate that are in a constant, slow motion.
What are the two types of Crust?
Oceanic and Continental
How did continental crust form?
When the earth cools down
How did Oceanic crust form?
Its constantly being recycled by the processes in the layer below
What is the temperature of the crust?
22*C, therefore solid
What is the composition of the oceanic crust?
Iron, Oxygen, Silicon, magnesium, aluminium, mainly basalt
What is the composition of continental crust?
Granite, sedimentary and metamorphic rocks, mainly granite
How deep is crust?
8km ( oceanic) but continental can go up to 70km.
What is the crust and the top of the mantle also called?
The lithosphere.
What is the lithosphere like?
It is brittle
What is the lower mantle called?
Asthenosphere
What is the Asthenosphere like?
its malleable
What temperature is the upper mantle?
1400 - 3000 * C, Liquid/ solid, the lower it is the liquidizer it gets
What composition is the upper mantle?
iron, oxygen, silicon, Magnesium and silicon
Where is The upper mantle?
Up to 670km below the earths surface.;
What temperture is the lower mantle?
3000*C, solid but hot enough to melt, pressure keeps it solid
What temperature is the lower mantle?
3000*C, solid but hot enough to melt, pressure keeps it solid
what is the composition of the lower mantle?
iron, oxygen, silicon, magnesium, amuminium.
Where is the lower mantle?
between 670 and 2890km below the earths surface.
What temperature is the outercore?
4000 - 6000 *C, liquid
What composition does the outer core have?
Iron, Nickel, Sulfur and Oxygen
Where is the outer core?
5150 km deep.
What temperature is the inner core?
5000 - 6000 *C, solid because of the pressure
What is the composition of the inner core?
iron and Nickel
Where is the inner core
its a ball in the center of the earth, 2500 km wide.
What and how do convection currents work?
Rock in the mantle is melted by heat from the Earth’s core, turning to magma.
The warm magma rises through the mantle to the Earth’s crust.
The magma at the surface is pushed to the side as more magma rises from the core.
This creates lateral pressure and carries the plate along the surface.
Eventually, the magma cools and begins to sink back down into the mantle.
This is called a convection current. This happens in a circular motion, Like soup.
This builds up lateral pressure and moves the plates with them outwards.
What is a tectonic plate?
A tectonic plate is a slab of solid rock, composed of both continental and oceanic crust.
What is a constructive margin?
Plates moving apart, creates new land
What is a margin
the lines between plates
What is a Destructive margin?
Plates moving together
What is a conservative margin?
Plates moving side by side
What is a constructive boundary like?
Caused normally by convection currents, this is two plates pulling apart normally causing a volcano between the 2 plates.
What does a constructive boundary have/ cause?
Normally between 2 oceanic plates.
Volcanoes
very small earthquakes
ocean ridges
What is a destructive margin like?
An oceanic and continental plate moving into each other. The oceanic one gets submerged. this can create volcanoes because of the melting expanding pressure of the oceanic plate.
What does a destructive margin have/ cause?
Oceanic and continental plates
volcanoes and earthquakes
ocean trenches
fold mountains
What is a collision margin like?
A collision boundary is 2 continental plates moving together. This creates fold mountains.
What does a collision margin have/ cause?
2 con plates
earthquakes
no volcanoes
fold mountains
What is a conservative margin like?
two plates travelling in different dirctions or the same, next to eachother. At different speeds.
How do mountains change over time?
Erosion
Weathering
Mass Movement
Tectonic activity
what are earthquakes?
vibrations caused by earth movements at plate margins and at major fault lines (cracks in the earth’s surface).
They can occur at all major plate margins but the most severe earthquakes are normally found at Conservative and Destructive margins.
how do earth quakes happen?
The two plates at a plate margin cannot move past each other easily.
The two plates lock together. Friction causes pressure to build up.
Suddenly the pressure is released and the plates jolt into a new position.
This causes seismic waves. The vibrations they cause are called an earthquake.
What is the fault?
A fracture in the rocks that make up the Earth’s crust.
What is the epicentre?
The point at the Earth’s surface directly above the focus.
What is the focus?
The point within the Earth where an Earthquake rupture starts.
What are plates?
Massive rocks that make up the outer layer of the Earth’s surface and whose movement along faults trigger earthquakes.
what are seismic waves?
Waves that transmit the energy released by an earthquake.
what are P waves?
expansions and compressions - longitudal
first waves to be recorded in an earthquake, fast.
what are love waves?
side to side
what are S waves?
up and down
slightly slower than P waves
S-waves cannot travel through air or water but are more destructive than P-waves because of their larger amplitudes
What are raleigh waves?
around but like up and down
closer to the surface
What is the richer scale?
The Richter Scale measures the magnitude of a tremor (how powerful it is) using an instrument called a seismometer 1 - 10
It is a logarithmic scale which means that a size ‘6’ on the Richter Scale is 10 times more powerful than a size ’5’ and 100 times more powerful than a size ‘4’.
What are the effects of an earthquake?
short term of an earthquake can include the ground shaking, buildings collapsing, and the ground splitting.
long term effects may include subsidence, tsunamis, fires, contamination of water supplies, gas leaks, and power outages.
How do we monitor earthquakes?
Using a seismometer
What is a seismometer?
An instrument used to mesure seismic wave
How can we use information from seismometer?
We can use the information from the seismometer to predict when a powerful earthquake might occur, so that people can be better prepared
what are the responses to an earthquake?
Short-term responses involve search and rescue and helping the injured.
Long-term responses may last weeks, months and years after a disaster. It involves rebuilding destroyed houses, schools, hospitals and preventing future disasters.
what is a volcano?
A volcano is an opening in the earth’s crust through which lava, volcanic ash, and gases escape.
what is the ring of fire?
A path that traces the boundaries of several tectonic plates around the Pacific Ocean
How many of the planets volcanoes are found in the ring of fire?
75%
How many of the planets volcanoes are found in the ring of fire?
75%
What is a volcanic eruption?
An emission of gasses and molten rock from the Earths core
- What do we call magma when it is above ground? How hot can it be?
Lava. 2000 F
What is a pyroclastic flow?
Searing hot gas and ash race down the side of a volcano at 100mph, burning everything in its path
How do we measure volcanic eruptions?
Volcanic Explosivity Scale (VEI) – a logarithmic scale with no upper limmit
Active volcano
if it has erupted recently it is likely to do so again e.g. Mount Etna, Sicily, Italy
Dormant Volcano
– (sleeping) a volcano which has not erupted for many years. For example, Mount Pinatubo, in the Philippines, erupted in 1991 after 500 years of dormancy.
Extinct volcano
– a volcano which has not erupted for many thousands or millions of years e.g. Castle Rock, Edinburgh, Scotland
What are the characteristics of a shield volcano?
Constructive plate boundary or hot spot
Wide base
Gentle slopes
Runny lava
Layers of new rock
Erupt frequently
Cone with wide base and gentle slopes
Made of lava only
Regular and frequent eruptions
Lava pours out with little violence
As the plates move apart, magma rises upwards from the mantle to fill the gap. This adds new rock to the spreading plates.
Some of the magma may also be forced out to the surface through a vent. Some volcanoes grow high enough to form volcanic islands.
An example of a shield volcano is Mauna Loa.
What are the characteristics of a composite volcano?
Narrow base
Steep slopes
Thick, viscous lava
Layers of rock and ash
Irregular, violent eruptions
Destructive plate boundary
How do tectonic plates move?
Rock in the mantle is melted by heat from the Earth’s core, turning to magma.
The warm magma rises through the mantle to the Earth’s crust.
The magma at the surface is pushed to the side as more magma rises from the core.
This creates lateral pressure and carries the plate along the surface.
Eventually, the magma cools and begins to sink back down into the mantle.
This is called a convection current.
How are fold mountains formed
Rivers erode material from the land surface and transport it out to sea.
Layers of deposited sediment build up over time forming sedimentary rock due to compression.
This moving together of rock leads to the layers of rock being pushed up and down.
The buckling and crumpling produces fold mountains.
Earthquake anatomy
An Earthquake is the shaking of the ground caused by sudden motions along faults, or fractures in the Earth’s crust.
WHat is the new mesure of earthquakes we use?
the moment magnitude scale
Fold mountains
– large mountain ranges where rock layers have been crumpled as they have been forced together
Mantle
– the dense, mostly solid layer of molten rock between the outer core and the crust
Composite volcano
– a steep-sided volcano that is made up of a variety of materials, such as lava and ash (it is the result of violent eruptions at destructive-subduction margins)
Lava
– name given to molten magma when it erupts at the surface
Vent
– the opening – usually central and single – in a volcano, from which magma is emitted
Pyroclastic flow
– a fast-flowing cloud of red-hot gases, cinders and ash erupted from a volcano.
Conservative plate boundary
– where a plate is slipping past another plate, pressure builds if the plates get stuck, then the plate jolts and releases energy as an earthquake
Plate margin
– the boundary where two plates meet
Lahar
– these secondary effects of a volcanic eruption are mudflows resulting from ash mixing with melting ice or water
Crust
– the shell or skin of the earth
Magma
– molten rock in the mantle
Convection currents
– the circular currents of heat in the mantle
Destructive subduction plate boundary
– where an oceanic plate collides with a continental plate. As a result, the oceanic plate subducts under the continental plate
Destructive subduction plate boundary
– where an oceanic plate collides with a continental plate. As a result, the oceanic plate subducts under the continental plate
Ocean trenches
– deep sections of the ocean, usually found at a destructive-subduction margin where an oceanic plate is sinking below a continental plate
