VOLCANOES AND PLATE BOUNDARIES Flashcards
Crust?
This is the outer layer of the earth. It is a thin layer between 0-60 km thick. The crust is the solid rock layer upon which we live.
Mantle?
Mantle- This is the widest section of the Earth. It has a thickness of approximately 2,900 km. The mantle is made up of semi-molten rock called magma. In the upper parts of the mantle the rock is hard forming the lithosphere but lower down the rock is soft and beginning to melt the asthenosphere.
Outer core?
This is the layer surrounding the inner core. It is a liquid layer, also made up of iron and nickel. It is still extremely hot, with temperatures similar to the inner core.
Inner core?
This layer is in the centre and is the hottest part of the Earth. It is solid and made up of iron and nickel with temperatures of up to 5,500°C. With its immense heat energy, the inner core is like the engine room of the Earth.
Destructive plate margins?
A destructive plate margin usually involves an oceanic plate and a continental plate. The plates move towards one another and this movement can cause earthquakes
Constructive plate margins?
At a constructive plate margin the plates move apart from one another. When this happens the magma from the mantle rises up to make (or construct) new land in the form of a shield volcano. The movement of the plates over the mantle can cause earthquakes.
Conservative plate margins?
At a conservative plate margin, the plates move past each other or are side by side moving at different speeds. As the plates move, friction occurs and plates become stuck. Pressure builds up because the plates are still trying to move. When the pressure is released, it sends out huge amounts of energy, causing an earthquake. The earthquakes at a conservative plate boundary can be very destructive as they occur close to the Earth’s surface. There are no volcanoes at a conservative plate margin.
At a conservative plate margin, plates slide past each other.
How do plates move-slab pull?
At destructive plate margins, the denser plate sinks back into the mantle under the influence of gravity, which pulls the rest of the plate along behind it. This is called slab pull.
Distribution of volcanoes?
Most volcanoes are distributed along the plate boundary. An example of a highly active earthquake zone is the west coast of North America and South America Occasionally, volcanoes are found in the middle of plates (e.g. Hawaii). These are called hot spots.
