(Solid) (Liquid) (Viscous) (Rocky) The crust moves when the mantle moves beneath it

 4 Pieces Evidence 1. Shape of the continents  Continents seem to fit together

2. Fossil Evidence  identical fossils found in Africa and South America  suggests continents were closer and connected  - too large to be carried by the wind  - too fragile to survive the ocean  - too far between the continents

3. Rock Evidence  Rock formations and Coal fields in Africa line up with matching formations in South America  Folded Mountain chain stretches across South Africa and matches one in Argentina  Similar rocks and structures of the Appalachian Mountains can be found in the British Isles and Scandinavia

4. Climate  Glacial deposits found in warm climate --- therefore: areas were once closer to the poles  Salt deposits in Northern States --- salt forms in tropical regions -- area was once warmer

 Explains most geologic processes  Evidence of mid-ocean ridges and ocean floor spreading helps explain continental drift  Links together ideas of continental drift and ocean floor spreading  Explains formations, movements, collision and destruction of the Earth’s crust

 Provides framework for understanding: ◦ - Mountains ◦ - Volcanoes ◦ - Earthquakes  - insights on how & why life on Earth has evolved  - helps understand the past & predict the future

 The upper mantle and the crust behave as a strong rigid layer called the lithosphere that is divided into plates  - slow continuous rate of movement – 5 cm/yr  - driven by convection currents in the Earth’s mantle

 1) Divergent Boundaries – 2 plates moving apart  2) Convergent Boundaries – 2 plates moving together  3) Transform Fault Boundaries – 2 plates that grind (slide) past each other

◦ the permanent magnetic field of a rock that shows the direction of the magnetic field at the time of the rocks formation ◦ when hot, minerals in newly formed rocks align themselves with the earth’s magnetic poles ◦ As the Earth’s magnetic poles change so do the direction of the rock’s magnetic poles

 strips of alternating polarity - mirrored on each side of ocean ridges  Therefore: Each strip that has a different polarity had to be formed at different time – supports sea floor spreading

◦ A link between deep-focus earthquakes and ocean trenches ◦ Shallow earthquakes occur near or at the trench ◦ Deep earthquakes occur toward the mainland

◦ Drilling of the ocean floor from the mid ocean ridge toward the coast lines ◦ Oldest rocks were found closest to the shoreline, youngest nearest the ridge ◦ Therefore: The ridge is producing new oceanic crust while older crust is being pushed toward the shoreline

◦ Rising magma from the mantle produces volcanoes along the floor of the ocean ◦ As plates move, new volcanoes are formed along the floor bottom above the hot spot ◦ Hawaii – age of features increase as you move away from the hot spot (Kilauea) ◦ Therefore: The plates are moving over the hot spot and forming new volcanic features.

 Convection Currents basic driving force ◦ Hot, less dense magma rises toward the crust while cooler, more dense magma sinks ◦ Plates move because of the uneven distribution of the Earth’s heat

 The pulling of old crust down in the mantle because by the downward flow of more dense magma in the convection current

The down-ward pull, from gravity, on the oceanic lithosphere at the ridge

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