The Theory of Plate Tectonics The Earth’s Crust The Theory of Plate Tectonics Monday, November 12, 2018Monday, November 12, 2018

This is what we know: Just like this egg… #1…the Earth’s shell is cracked into many smaller pieces.

#2 We call these pieces of the Earth’s crust tectonic plates. (because that makes scientists sound really smart)

#3 There are 13 main plates covering the planet.

Can you name the 5 largest plates?

These plates are made of both continental crust (land) and oceanic crust (water).

Name one plate that is all oceanic crust.

Name one plate that is made up of oceanic crust and continental crust.

#4 These plates are moving very slowly (3 to 5 cm’s a year). That’s about as fast as your fingernails grow. So Alfred Wegener was right after all.

We can measure how fast they’re moving by using satellites in space and GPS stations on Earth.

#5 Wherever the edges of the plates rub together or collide they cause earthquakes, volcanoes and mountains.

#5 Wherever the edges of the plates rub together or collide they cause earthquakes, volcanoes and mountains.

Why don’t we have any large earthquakes or volcanoes in Fredericton

Why do they have so many earthquakes at the Presidio Why do they have so many earthquakes at the Presidio? (in San Francisco)

#6. Plates can rub or bump together in three different ways: 6A. Divergent Boundary – where two plates are moving apart. This happens on the bottom of the sea floor at places called Ocean ridges (underwater volcano chains). New crust is created at divergent boundaries. We call it sea floor spreading. Click here for Animations

6B. Convergent Boundary – where two plates collide. Old crust is destroyed when two plates collide. They can create either volcanoes, earthquakes, or mountains. Click here for Animations

6C. Transform Faults – When two plates slide or scrape past each other. These create earthquakes and mountains e.g. San Andreas Fault in California Click here for Animation

The San Andreas fault in California cuts right across the state.

San Andreas Fault as seen from an airplane.

The San Andreas Fault in California will eventually cause southern California to break off and move north…to Canada! Disney World Play video

Click here for a Review Animation

# 7 J. Tuzo Wilson, a Canadian scientist, discovered transform faults in 1965. (He also discovered “hot spots) His work was vital to the overall theory.

This is what we don’t know: We’re not completely sure what causes the plates to move, which is why this is still a theory.

Our best guess is that circulating convection currents deep inside the Earth slowly push the plates that are “floating’ on top. PLAY MOVIE This sounds like a good idea but there is no way to prove it (yet).

Bonus Question: How could these dinosaur footprints end up on the side of a cliff?!

Hint: This coral reef was lifted more that five feet out of the water when two plates collided during an earthquake.

Scientists also discovered new forms of life at the bottom of the ocean living off of energy from the volcanoes! In complete darkness!!! Videos Tube Worms Black Smoker