Plate Tectonics - earth

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motion.

Earthquakes occur where plate rub against one another

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Tectonic Plates

Volcanoes

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Tectonic Plates

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Tectonic Plates

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Tectonic Plates

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Tectonic Plates

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Tectonic Plates

Another source of

evidence is based

on seafloor ages

which get younger

as we approach

sea floor ridges

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Tectonic Plates

Our final piece of

evidence is the

magnetic record

of the ocean floor.

This shows the

pattern of reversal

and we find a near

perfect mirror image

on opposing sides

of the ridge

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Tectonic Plates

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Tectonic Plates

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Tectonic Plates

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Composition vs. Motion

We can look at the interior of the Earth based

on the composition of the rocks or based on the movement

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Based on Composition

Crust – solid, relatively low density silicate rock

Mantle – Semi fluid, denser, mafic (iron and magnesium bearing) rocks

Core – Liquid then solid iron and nickel with traces of heavier elements

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Based on Motion

It turns out that the upper section of the mantle is adhered (stuck to the underside side of the crust to form what we call tectonic plates

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Plate Types

Oceanic plates: basalt

Dark (black) and dense rock type composed of silicates, iron and magnesium

Continental plates – granite and andesite

Light colored (pink, white and gray) and low density rock type composed almost entirely of silicates.

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Plate Boundaries