Theory of Plate Tectonics 1. Continents appear to “drift” with time

Continental drift

Evidence for continental drift 1. Puzzle like fit of continents

Fossils correlation

Rock Correlation

Glacier Evidence

Mountain Belts

Buckled Mountains on Continental Margins

Theory of Plate Tectonics Continents appear to “drift” with time Lithosphere is broken up into rigid “plates”, that are moving

Earth’s Plates

Plate Plate ASTHENOSPHERE

To keep the oceans from spilling out And losing all the fish! The plates can’t curl down They must curl up To form a kind of dish To keep the oceans from spilling out And losing all the fish! - King, 1971, Nature

Theory of Plate Tectonics Continents appear to “drift” with time Lithosphere is broken up into rigid “plates”, that are moving There are three types of plate boundaries: Divergent Convergent Transform

3 types of plate boundaries: Divergent – 2 plates move away from each other, such as a mid ocean ridge where sea floor spreading occurs 2. Convergent – where 2 plates collide 3. Transform boundary – where 2 plates slide along side of one another

Why do the plates move?

Heat – the driving force

Mid-Atlantic ridge Sea Floor Spreading! Did you know that the ocean floor in the Atlantic is growing by 3cm per year? Which of the following pairs of continents are moving further away from each other? Europe and Africa Europe and North America South America and North America

Divergent Plate Boundary Creation of An ocean Sea Floor Spreading

Iceland – a country being split apart is on the Mid-Atlantic Ridge

A new ocean forming?

Rift Valley in Africa

Magnetic Anomalies Prove Seafloor Spreading

The further from a ridge, the older the rock oldest youngest

Divergent plate boundaries MID OCEAN RIDGE A Ocean B Oceanic Crust Mantle Where would you find older rocks – at A or at B?