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Starting from the center, what is the Earth’s structure?
Inner core
Outer core
Lower mantle
Upper mantle (the asthenosphere)
The lithosphere
The crust (the top of the lithosphere)
What is the deepest artificial point on Earth?
The Kola Superdeep Borehole in the Pechengsky District, Russia
Explain the inner core?
Solid ball
Made of Iron and Nickle
Under high amount of pressure - as it has the weight of the Earth pushing against it
Within it, radioactive elements like uranium and thorium are decaying. Radioactive decay gives off heat. This heat is responsible for the Earth’s internal energy and it spreads through the different layers
5000 degree celsius
What causes the inner core to remain solid?
the fact that it has the pressure of the Earth pushing on it.
What is responsible for the Earth’s internal energy
The heat that is given from the radioactive element decaying in the inner core of the Earth
Explain the outer core?
Molten (liquid) layer
Iron and Nickle
Surrounds the inner core
Heat from the inner core creates convection currents in the outer core, which transfers heat to the mantle above
Explain the mantle?
Largest layer
Solid rock apart from the very top where it behaves like a dense fluid
Top layer is known as asthenosphere
Asthenosphere constantly moves and flows due to convection current, which moves the solid lithosphere above
Explain the lithosphere
Solid rock that lies on top of the asthenosphere
Majority of the lithosphere is technically in the mantle, but the very tpo of the lithosphere is the Earth’s crust
The crust is split into multiple large slabs called tectonic plates
The crust is either continental or oceanic
Plates move due to movement of the liquid asthenosphere
What is continental crust?
Crust that makes up our land (ols, less dense and thick)
What is oceanic crust?
Makes up the ocean floor
Younger but still very old, dense and thin
Why do plates move?
They move due to the movement of the liquid asthenosphere.
Where do convection current occur?
Within the upper mantle (asthenosphere)
Explain how convection currents happen?
Energy from radioactive decay in the core heats up the fluid asthenosphere
The hot liquid is less dense than its surroundings, so it rises upwards
When it reaches the top, it cools and becomes more dense, and therefore sinks back down to the bottom
It is heated up again, and the cycle continues
The plates, which lie on top, are pushed and pulled by the convection currents in the asthenosphere
What is the lithosphere divided up into?
Continental crust
Oceanic crust
What is the depth of the continental crust
0-100km thick
usually 30-50km thick
What is the depth of the oceanic crust
usually 6-8km thick
What is the physical state of the continental crust
solid
what is the physical state of the oceanic crust?
solid
What is the density of the continental crust
2.7
What is the density of the oceanic crust?
3.3
What is the composition of the continental crust
Rocks similar composition to granite
What is the composition of the oceanic crust?
Rocks similar to basalt
What is the temp of the continental crust?
air temp 900
What is the temp of the oceanic crust?
air temp is 900
What is the mantle divided up into?
Asthenosphere
Lower Mantle
What is the depth of the asthenosphere?
Starts anywhere from 35-250km to 700km
What is the depth of the lower mantle?
700-2900km
What is the physical state of Asthenosphere?
Partially molten/fluid
What is physical state of the lower mantle?
Solid
What is the density of the asthenosphere?
3.4 - 4.4
What is the density of the lower mantle?
4.4 - 5.6
What is the composition of the asthenosphere?
Silicates (made of silicon)
What is the composition of the the lower mantle
Silicates (made of silicon)
What is the temp of the asthenosphere?
900 to 1600
temp of the lower mantle?
1600-4000
What is the core divided into?
Outer core
Inner core
What is the depth of the outer core
2900km - 5270km
What is the depth of the inner core?
5270km - 6370km
What is the physical state of the outer core
liquid
What is the physical state of the inner core?
Solid
density of the inner core?
12.6 - 13.0
density of outer core?
9.9 - 12.2.
composition of outer core?
iron and nickle
composition of inner core
iron and nickel
temp of outer core
4000 - 5000 degrees
temp of inner core
around 5400 degrees
What is a plate boundary?
It is where the plates meet.
How long has plate tectonic movement been happening ?
Hundreds of millions of years
Explain the continental drift theory in detail?
By Alfred Wegener
in the early 20th century
suggest that the Earth's continents were once joined together in a single supercontinent called Pangaea.
Over time, these continents gradually drifted apart and moved to their current positions.
Wegener supported this theory with evidence such as:
the fit of the continents
matching geological formations
similar fossil records across different continents
The theory was met with skepticism due to a lack of credibility.
It was later supported by the discovery of plate tectonics, which explained that the Earth's lithosphere is divided into several large plates that float on the semi-fluid asthenosphere
The continental drift theory revolutionised our understanding of Earth’s geological history
What was the evidence for the continental drift theory?
the fit of the continents
matching geological formations
similar fossil records across different continents
Give an example of a plate that is continuously moving?
The atlantic ocean is growing as the USA is moving away from the UK about 2-5 cm a year
Name all the tectonic plates ?
There are several major tectonic plates on Earth, including:
African Plate
Antarctic Plate
Australian Plate
Eurasian Plate
North American Plate
South American Plate
Pacific Plate
Indian Plate
Arabian Plate
Caribbean Plate
What are the types of plate boundary?
Divergent
Convergent/Destructive
Conservative
What is the divergent plate boundary?
Plates move away from each other
Explain what happens at a divergent plate boundary?
When the two plates are pulled apart, magma rises in between the gap left by the two plates separating. Lava then pours out onto the surface.
Volcanoes form in the areas where lava pours out. This lava is usually runny and free-flowing, which creates flatter volcanoes. Earthquakes also occur here as the plates shake and vibrate when they move apart. This process can happen on continental crust or oceanic crust .
In the ocean:
new land is formed - sea floor spreading
in the land:
when the lava cools, it form rocks. Over time the rocks build up and can form islands e.g. Iceland
What can be found at a divergent plate boundary?
Earthquakes
Volcanoes
What kind of volcanoes can be found at divergent plate boundaries
Flatter volcanoes
Why can earthquakes occur when there is a divergent plate boundary?
Because the plates shake and vibrate as they move apart
What type of crusts can a divergent plate boundary be on?
continental
Oceanic
What is sea floor spreading?
Sea floor spreading is the process by which new oceanic crust is formed through volcanic activity at mid-ocean ridges. As magma rises to the surface, it cools and solidifies, creating new crust. This process pushes the existing crust apart, causing the sea floor to spread and the continents to move. It is a key component of plate tectonics and helps explain the movement of Earth's lithospheric plates.
What is a rift valley?
On continental crust, a divergent plate boundary causes huge fractures in the land, creating a low land region known as a rift valley
What is a famous rift valley?
The East African Rift Valley
Explain the East African Rift Valley
The rift zone stretches for thousands of kilometres down East Africa, and many volcanoes have historically been present in this area. If the divergent plate boundary continues on its path, the East of Africa may eventually split off from the rest of mainland Africa, and will be separated by sea.
What is a convergent/destructive plate boundary?
When the plate move towards each other
Explain what happens at destructive or convergent plate boundary
This is when the plate move towards each other. This causes one of the plates to subduct (sink) below the other into the mantle, where it is destroyed.
Give an example of a convergent plate boundary?
For example, the oceanic crust is moving towards continental crust. This is happening off the west coast of South America where the Nazca Plate is subducting below the South American Plate.
What processes must happen for a convergent or destructive to cause earthquake and volcanoes?
The denser oceanic crust is subducted below the continental crust
The plate that is subducting leaves a deep ocean trench
Friction between the two plates causes strong, deep earthquakes
The oceanic crust is melted as it is pulled deeper into the mantle, creating magma.
This magma causes pressure to build up under the crust.
Eventually the magma pushes out through weaknesses in the crust, creating explosive volcanoes.
Explain destructive or convergent plate boundaries between two oceanic crust?
Where the denser plate sinks below and islands in the ocean can form.
Give an example of convergent plate boundaries between two oceanic plates?
The Mariana trench
Explain destructive or convergent plate boundaries between two continental crust?
When two continental plates meet, neither plate can subduct below the other. The crust is instead crumpled upwards by the pressure building between two plates, creating fold mountains.
Give an example of two continental plates meeting at a destructive plate?
An example of this is the Himalayas, which formed due to the Indian Plate and Eurasian Plate colliding.
What landforms can be seen in when two continental plates meet at a destructive boundary?
Folding Mountains
What is a conservative plate boundary?
Parallel plates move in different directions or at different speeds in relation to each other
Explain what happens a conservative plate boundary?
At a conservative plate boundary, parallel plates move in different directions or a different speeds in relation to each other. When these plates move side by side, friction builds between the plates. The friction builds up over many years, and eventually the pressure becomes so large that the plates eventually move in a sudden jolt.
This releases a lot of energy which send vibration through the ground. This is an earthquake
On oceanic crust, this movement can displace a lot of water, which cause large waves called tsunamis.
On continental crust, fault line can occur where the ground is cracked by the movement.
There are no volcanoes on conservative plate boundaries because no magma is being generated.
What is a hotspots?
Hotspots are area of volcanic activity that are not related to plate boundaries.
Explains what happens at a hotspot?
Hot magma plumes from the mantle rise and burn through weaker parts of the crust. This can create volcanoes and islands. The plume stays in the same place but the plates continues to move, which sometimes causes a chain of island.
What landforms can form at hotspots?
Volcanoes
Islands
Give an example of a chain of islands
Hawaii
Explain Volcanoes on Divergent plate boundaries
Non - explosive
Runny, fast flowing lava - made up of basalt (very hot and has low viscosity (thickness))
This creates shallow sided (flat) shield volcanoes.
Explain Volcanoes on convergent plate boundaries
Very explosive - due to the high pressure the magma is under
Hot gas, ash and rock is spewed from the volcanoes
Fast, extremely hot clouds of gas, ash and debris can roll down the side of the volcano in a pyroclastic flow
Lava is made of andesite - causing it to be viscous and very slow flowing
Steep sided composite volcanoes are formed from these eruption
What is a pyroclastic flow?
A pyroclastic flow is a fast-moving mixture of hot gas, ash, and volcanic rocks that flows down the slopes of a volcano during an explosive eruption. It can reach speeds of hundreds of kilometers per hour and is extremely dangerous, capable of destroying everything in its path.
Explain earthquakes on divergent?
Smaller earthquake - less built up friction
Explain earthquakes on Conservative Boundaries?
Very destructive and intense
If an earthquake is shallow, the earthquake can cause very intense shaking, which can bring down buildings, break pipes and destroy infrastructure
Explain earthquakes on convergent Boundaries?
Very strong.
These earthquake can be very severe, especially if they are shallow.
What is the Richter Scale?
The Richter Scale is the scale that seismologists use to measure the strength on an earthquake. The scale is logarithmic, which means each number is 10x bigger than the last and approximately 31.6 times more energy released. The scale ranges from 0 to 10,
What is tsunamis?
Earthquake can trigger huge waves of seawater to travel across the ocean and hit a coastal area. This large wave is known as a tsunami, and can cause extreme flooding and damage to property.
Explain the formation of tsunamis?
When an oceanic crust is jolted vertically during an earthquake, all of the water above this plate is displaced.
The water travels fast but with a low amplitude (height). Larger waves began rippling across the ocean away from the earthquake’s epicenter
As it gets closer to the coast, the sea level decreases so there is friction between the sea bed and the waves.
This causes the waves to slow down and gain height, creating a wall of water that is on average 10 feet high, but can reach 100 feet.
What is the anatomy of a tsunamis?
The tsunami formed when an earthquake vertically shifted the seabed by several meters
What is a composite volcano?
A composite volcano, also known as a stratovolcano, is a tall and steep-sided volcano formed by alternating layers of lava flows and pyroclastic materials. These volcanoes are characterized by their explosive eruptions and can be found in subduction zones where tectonic plates collide.
What are some examples of composite volcanoes?
Examples of composite volcanoes include Mount Fuji in Japan and Mount St. Helens in the United States.
What is a shield volcano?
A shield volcano is a type of volcano characterized by its broad, gently sloping shape and built-up layers of basaltic lava flows.
It is formed by the eruption of low-viscosity lava that spreads out in all directions, creating a wide, shield-like structure.
Shield volcanoes are typically not very explosive and are associated with hotspots and divergent plate boundaries.
Examples of shield volcanoes?
Examples of shield volcanoes include Mauna Loa in Hawaii and the Galapagos Islands.
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