Welcome! Please get out: Rates of Plates Part 2 (blue) and your Sinking Slabs worksheet (yellow) Get a BSCS textbook Biology Journal A writing utensil Your brain…activate it! 50,000,000 years

Warm-Up: #1 A plate is moving at a rate of 2 cm/ year. How many years would it take the plate to move 1,600,000,000 cm? #2 How many centimeters are in 5,400 meters?

Warm up Review #1 1 year x 1,600,000,000 cm = 800,000,000 yrs 2 cm #2 100 cm x 5,400 m = 540,000 cm 1 m

Let’s review our past work… Have both Mountainous changes part 1 and part 2 in front of you

Homework Review Scaling up to Mt. Change Pts I & II Big Take Homes: Do tectonic plates move quickly? Slowly? How can such a slow process lead to such great changes? Can you think of an analogy of something else that moves very slowly, but can lead to great changes? How does coral end up in places that aren’t under water? Do all the locations change at the same rate? What might lead to differing rates of change in the mountain heights? Why are some mountains jagged, and other mountains more rounded? What makes mountains? What makes them smaller?

Let’s take some notes… Open up your Biology Journal to the Class Notes Section. If you fall behind you can always review my presentation on my SWIFT site.

Principle of Superposition In a set of layered (sedimentary) rocks, the oldest must be at the bottom and the youngest at the top.

Example!

Youngest Rocks Oldest Rocks

You don’t make an ice cream cone from the top down!

Principle of Original Horizontality Sediment is deposited in horizontal layers… (thus sedimentary rock layers are initially horizontal). So if layered rocks are tilted, they probably didn’t start that way – something changed. Not original position

What’s Inside the Earth?

Theory of Continental Drift Continents were formed from the drifting apart of one super continent Pangaea http://www.classzone.com/books/earth_science/terc/content/visualizations/es0806/es0806page01.cfm?chapter_no=visualization Found evidence of similar fossils and geological formations on different continents The shape of continents also seemed to “fit” together

Fossil & Geologic Evidence Big flaw with theory: How did the continents actually move?

Theory of Plate Tectonics Outer “shell” of Earth is broken into plates Plates are carried by convection cells in mantle Moving plates collide, diverge, or slide by each other

Convection cells in (upper mantle) cause sea floor spreading

Ocean and Continental Crust OCEAN crust Denser Thinner Eventually subducted Relatively young CONTINENTAL crust Less dense Thicker Rarely/never subducted Oldest crust on Earth

How do tectonic plates interact? Three Major Ways: Convergent – Come Together Divergent – Drift Apart Transform – Slide side by side

Convergent Two plates collide together. The faster they move, the stronger the seismic events will be (stronger earthquakes, taller mountains, etc). This is the way huge mountains are made.

Convergent Boundaries 1. Continental/Oceanic Denser ocean crust is subducted (pulled) under Deep trenches, mountains, strong earthquakes Melting oceanic plates turn into magma http://education.sdsc.edu/optiputer/flash/subduction_5.htm Examples: Andes Mts. Cascade Mts.

Convergent Boundaries 2. Oceanic/Oceanic Slower plate is subducted (pulled under) Outcome = volcanic islands, strong earthquakes, tsunamis, deep trenches Ex: Aleutian islands (Alaska), Hawaiian Islands, Japan, Southeast Asia http://education.sdsc.edu/optiputer/flash/convergance2.htm

Himalayan Formation http://www.edumedia-sciences.com/en/a823-formation-of-the-himalayas

Divergent Boundary, Seafloor Spreading-Magnetic Reversals This kind of plate boundary usually results in ocean spreading ridges (underwater mountains that expand)

Divergent Boundary Normal Fault Mostly below the ocean Sea Floor Spreading - Forms new crust http://education.sdsc.edu/optiputer/flash/seafloorspread.htm Example: Mid Atlantic Ridge, Rift Valley in Africa

Great Rift Valley- Africa

Age of Seafloor

Transform Boundaries Transform Boundary Description: Two plates slide by each other. Creates: Earthquakes and underwater Mountains Ranges Where: San Andreas and Turkey Connection: Rubbing your hands together or Sneakers on the gym floor.

Transform Plate Boundaries 2 plates sliding in opposite directions E.g. San Andreas Fault http://education.sdsc.edu/optiputer/flash/SanAndreas.htm

Faults Fractures in crust Occur along plate boundaries, but occasionally occur in the middle of a plate Rigidity of crust builds up tension; eventually slippage occurs to release tension  this is an earthquake

Rates of Plates Packet Part 1 and 2 & Sinking Slabs WS Complete both packets. Both packets are due at the beginning of the next class. QUIZ on Tuesday, Sept. 26 (Blue) or Sept. 27 (Gold) Make sure you know the following for the QUIZ: Convert from cm to m Calculate rates (ex. 3cm/year…how many years to move 1,200,000 cm?) Calculate slope Vocabulary definitions Boundary types and events that occur there. Difference between rifts and trenches