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Plate Tectonics

+Aim & Learning Target

Aim: How can we describe what causes the movement of the

plates?

Learning Target: I can describe what causes the movement of the plates

+Do Now

+The Theory of Plate Tectonics

+1. The Theory of Plate Tectonics states that

Earth’s lithosphere (crust + upper mantle) is divided into sections called lithospheric plates.

+2. Plate Motion – The theory of Plate Tectonics states that these lithospheric plates are in motion and “float” or ride on the asthenosphere.

3. Direction of Plate Movement – the movement and interaction of tectonic plates creates 3 types of plate boundaries: the arrows on the tectonic map in your notes show the relative motion.

+Pulse check

Name some of the tectonic plates? How do you know this?

Eurasian, North American, South American, Indian-Australian, Pacific, Antarctic, African

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Types of Plate Boundaries

A. Divergent Plate Boundaries – where 2 plates are moving apart

1. Ocean – Examples: Mid-Atlantic Ridge

+ What happens to the age of oceanic crust as distance increases from a ridge?

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2. Continental

Examples: Great Rift Valley, Africa

B. Convergent Plate Boundaries – Where 2 plates come together or collide.

1. Oceanic-Continental – Subduction Zone

Example: Nazca (oceanic) subducts under South American (continental)

2. Oceanic – Oceanic: Trenches

Example: Trenches and island arcs of Japan and Alleutian Islands (Alaska)

3. Continental – Continental –

Example: Indian/Australian Plate Colliding with Eurasian Plate forming the Himalaya Mountains

+C. Transform Plate Boundaries – 2 plates that “slip” past one another. Ex: San Andreas Fault

+Pulse check

What type of plate boundary is found between the indian australian plate and the antarctic plate?

Divergent

+Pulse check

What causes the Mid Atlantic Ridge?

Divergent plate boundcary between South American and African Plate.

+What’s the driving force beneath plate tectonics?

Convection Currents

Hot, LESS dense material from deep within Earth’s mantle rises. When this material cools near the surface, it becomes MORE dense and sinks. The resulting convective flow of this material in the mantle CARRIES/MOVES lithospheric plates across the surface of Earth.

+Pulse check

What else moves in these convection currents?

Water & Air