Tectonic Plates
- Created by: Luke Staddon
- Created on: 28-03-14 19:37
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- Tectonic Plates
- Earth's Surface
- The Earth has a layered structure.
- These plates move around.
- Magnetic clues in rocks
- Sedimentary rocks
- Earth's Surface
- Crust and the upper part of the mantle are cracked into a number of large pieces called tectonic plates. These float on the mantle
- Earth's Surface
- The Earth has a layered structure.
- These plates move around.
- Earth's Surface
- Most of the plates move at speeds of a few CM per year.
- This means that different parts of the world as we know it today have acctually been located in different positions and have moved slowly over the Earth's surface
- When tectonic plates move away from each other under the sea, the exposed mantel rises up through the gap and solidifies to form new crust
- Magnetic clues in rocks
- When the crust forms it's magnetized by the Earth's magnetic field.
- Every 1/2 million years the Earth's magnetic field swaps, so the rocks have either normal polarity or reversed polarity when they cool
- The pattern of normal and reversed polarised rocks can be used to estimate the age of different parts of the Earth's crust, and track very slow movement of the tectonic plates
- As tectonic plates move, rocks found in Britain toady may have formed in different positions on the Earth's surface and therefore in different climates.
- Sedimentary rocks
- Fossils - these are remains or imprints of dead organisms. they tell you the age of the rock and the condition under which it formed.
- Underwater - Contains shells and has ripples on it created by the sea or rivers
- Sediment - forms in rocks will either have been carried by water or air. By looking at the shape of grains found in sedimentary rocks you can tell if the rock was formed underwater (water-borne grains) or on the surface (air-blown grains)
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