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Restless Earth

Slide 2

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• Legenda: The Earth consists of four concentric layers: inner core, outer core, mantle and crust. The crust is made up of tectonic plates, which are in constant motion. Earthquakes and volcanoes are most likely to occur at plate boundaries.
• The Earth is made up of four distinct layers:
• The inner core 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.
• The outer core 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.
• The mantle 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, but lower down the rock is soft and beginning to melt.
• The crust 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.
• There are two different types of crust: continental crust, which carries land, and oceanic crust, which carries water. Oceanic crust is denser than continental crust and so it sinks beneath the continental crust when they are force together.

Slide 3

• The Earth's crust is broken up into pieces called plates, like pieces of a jigsaw. heat rising and falling inside the mantle creates convection currents generated by radioactive decay in the core. The viscous moving magma sticks to the plates and moves them in different directions depending on the flow of the convection current. Where convection currents diverge near the Earth's crust, plates move apart. Where convection currents converge, plates move towards each other.
• Plate tectonics is the term used to describe the movement under the Earth's crust and the movement of plates.
• The point where two plates meet is called a plate boundary. Earthquakes and volcanoes are most likely to occur either on or near plate boundaries.
• There are three different type of boundary:
• At a tensional, constructive or divergent boundary the plates move apart.
• At a compressional, destructive or convergent boundary the plates move towards each other.
• At a conservative or transform boundary the plates slide past each other.
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Slide 4

• At a constructive plate margin, the plates move apart due to the direction of the convection currents beneath the plates. As the plates slowly move apart, fissures open up which give magma a passage way up onto the surface. This is accompanied by earthquakes. When the magma eventually cools, it forms igneous rock, and this process is repeated many times. Eventually, the new rock forms a volcanoes.
• constructive boundaries are mostly found under the sea