The Structure of the Earth
Structure of the Earth
The Crust Outer layer of solid rock Quite thin (10km 60 km) Contains the earths plates
The Mantle Hot, soft rock (4000 o C) Made up of molten rock (magma) Slow moving currents called convection currents
The core The centre of the earth is called the core Temperature is highest at the core Temperature of 5,000 7,000 o C Made of iron and nickel
Convection currents in the mantle
Pangaea
The Crust
Plate boundaries Plates collide with each other. Example: Eurasian plate and African plate Plates separate from each other. Example: American and African plate Plates slide past each other Example: American plate and Pacific plate
World s Mountain Ranges
Mount Everest What two plate boundaries have formed Mount Everest?
Mountain ranges under the sea
Mid Atlantic Ridge How is the Mid Atlantic Ridge formed? It formed when the Africa and Eurasian plate separated from the American plate.
What island has formed along the Mid-Atlantic Ridge?
Mid Atlantic ridge video Mid-Atlantic Ridge - YouTube
Plates Colliding
Where plates collide Convection currents in the magma help push the plates towards each other. When they collide one plate is pushed below the other (compression). Fold mountains are then formed. Earthquakes occur here.
Plates Separating
Where plates separate Convection currents in the magma can sometimes pull plates apart. Magma rises up through the crust were the plates separate forming volcanic islands. The Mid-Atlantic Ridge was formed in this way.
Plates Separating
Plates separating Video of Iceland volcano eruption, giant ash clouds from Grimsvotn YouTube
Fold Mountains Fold mountains form when plates collide When plates collide and compress, the earths crust buckles to form fold mountains. Youngest fold mountains (35 million years old): The Rocky mountains Alps in Europe Andes in South America
Fold Mountains
Irelands fold mountains Irelands fold mountains are very old. Irelands fold mountains are quite small compared to the Alps. They are much older so have been worn down. Example: Mountains in Munster (250 million years old).
MacGillycuddy s Reeks
Loss of life Disadvantages of earthquakes Buildings can collapse Roads crack and bridges can fall Gas lines can break and go on fire. Tsunamis (large waves) cause death
Effects of earthquake
Effects of earthquakes
Video of tsunami TERRIBLE NEW FOOTAGE of 2011 TSUNAMI IN JAPAN! - YouTube
How might we reduce damage caused by earthquakes: Earthquake proof building Build on stable ground Study Seismic readings to predict earthquakes.
Seismic Reading
Earthquakes earthquakes in california - YouTube
What is an earthquake?
Features of earhtquakes When plates collide, rocks are compressed which sends out a shock wave from the focus. Epicentre: the surface area directly above the focus (earthquake strongest here) Fault lines occur where two plates are in contact with each other.
Features of Earthquakes Focus: point within the crust where earthquake occurs. What are aftershocks: They occur after the main earthquake. Can occur within hours or days of main earthquake.
Earthquake instruments Seismograph identifies tremors in the crust Richter scale the force of an earthquake is measured using this scale seismograph - YouTube
Richter Scale
Earthquakes in California
Earthquakes in California California suffers from severe earth quakes The Pacific plate and the North American plate slide past each other. In 1906 a strong earthquake rock San Francisco. Much of the city was destroyed. Los Angeles Earthquake - YouTube
Volcanic Activity When plates separate or collide with each other, magma can sometimes force its way up to the surface. When magma reaches the earth s surface it is then called lava.
Volcanic mountain Volcanic mountains are formed when lava passes through a hole called a vent.
Lava Fields
Volcanic mountain
Lava fields Lava Oct '02 - YouTube
Volcanic Mountain
Mt Etna in Italy
Volcanic Mountains New dramatic footage of Chile Puyehue volcano eruption - YouTube
Types of volcano Active: Still erupts regularly (Etna and Vesuvius)
Types of Volcano Dormant: Have not erupted for a long time but may erupt again (Cotopaxi in Ecuador)
Types of volcano Extinct: have not erupted in historic times (Slemish in Co. Antrim).
Pacific Ring of fire Earthquakes and volcanoes occur near the meeting place of plates. A large earthquake and volcano zone occurs in the Pacific zone. This zone is known as the Pacific Ring of Fire.
Pacific Ring of Fire
Why does Ireland not experience strong earthquakes or volcanoes? Ireland is not located near any plate boundary which reduces the risk of strong earthquakes.
Humans and Volcanoes Land surrounding volcanoes can be very fertile which is good for farmers. Some volcanoes provide valuable hot water supplies. Tourism
Disadvantages of volcanoes: Volcanic eruptions have buried cities and kill many people. Example: Pompeii
Disadvantages of volcanoes Destroys farmland and releases large amounts of poisonous gases.
Advantages/ Disadvantages of volcanoes Pompeii ash volcano excavation - YouTube
Geysers in Iceland Hot water geysers in Iceland Double-Erruption of Strokkur Geysir (Iceland) - YouTube