Ch 10 Plate Tectonics

• Section 10.3 Theory of Plate Tectonics

Ah – ha!

• Scientists realized that the continental drift idea could be explained by sea floor spreading……(early 1960’s)

• The Earth’s crust is broken into “plates” that move, grow, and subduct.

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• Plates are made of ______ and upper ________; these compose the _________.

• These ______ plates float and move atop the plasticlike layer called the ________.

• Plates are made of crust and upper mantle; these compose the lithosphere.

• These rigid plates float and move atop the plasticlike layer called the asthenosphere.

The Earth’s Plates

Global Plate Motions

Types of Boundaries

ConvergentDivergentTransform

Tectonics – study of formation of crustal features

• Oceanic crust – thin, dense, basaltic

• Continental crust – thick, less dense, granitic

Convergent Boundary

Ocean plate – continental plate

Convergent Boundary

ocean plate – ocean plate

Convergent Boundary

Continental plate – continental plate

Himalayan Mountains

Divergent Boundary

Common at Mid-Ocean Ridges (M-O-R)

East African Rift Valley –

Red Sea

Transform Boundary

What makes the plates move?

Plates move like they are groceries on a conveyor belt

What Drives It: Convection

Examples of convection

Examples of convection

Plate Tectonics

• Features on Earth’s surface are a result of interactions of plates at their boundaries• Earthquakes

• Faulted and folded mountains

• Volcanic landforms

• Rocks

o Noo Plates are destroyed as fast as

they are created (2 ways)o Plates may be subducted and

melted or may push be pushed upward to form mountains

So is the Earth getting bigger?