Plate Tectonics Subtitle

First, let’s back up… What’s continental drift? The movement of the CONTINENTS over a long period of time But why are they moving??? Continents move because they are driven by convection currents in the mantle Why are there convection currents in the mantle? The Earth’s core heats up the mantle by conduction and radiation This causes the bottom of the mantle to heat up and become less dense The less dense material “floats” to the top, and as it cools becomes more dense Now that it is more dense it wants to sink back down …oh, you mean it makes a convection current!!

First, let’s back up… So if the continents are moving…what are they moving on? The continents sit on Plates Plate – A broken chunk of the lithosphere that moves as it is affected by convection currents. The Plates are the things that are actually moving…the continents are just along for the ride.

THE THEORY OF PLATE TECTONICS Scientific Theory vs. Scientific Fact Theory – A hypothesis that is widely excepted and is supported by many different experiments Fact – A verifiable observation that is the same everywhere. It has been proven over and over again. Theory’s help explain a fact.

THE THEORY OF PLATE TECTONICS Theory of Plate Tectonics – states that pieces of the Earth’s Lithosphere are in slow, constant motion, driven by convection currents in the mantle. It explains the formation, movement, and subduction of the Earth’s plates. If this is a theory…what FACT does it help explain? Continental Drift!

Plate Boundaries… Because the plates are moving in different directions, there are 3 major different possible interactions between the plates. Divergent Boundaries – Plates separate. Results in a Rift Valley Convergent Boundaries – Plate collide. Results in: Mountains OR Volcanoes and trenches Transform Boundaries – Plates Scrape each other. Results in earthquakes

Divergent Boundaries OR

Convergent Boundaries Oceanic – Oceanic Collision

Convergent Boundaries Oceanic – Continental Collision

Convergent Boundaries Continental– Continental Collision

Transform Boundaries

Apply it The San Andreas Fault is a plate boundary between the Pacific Plate and the North American Plate. What type of boundary is it? What might happen to California in a few million years?