CONTINENTAL DRIFT THEORY
Proof or crazy idea?
CONTINENTAL DRIFT THEORY What is Continental Drift Theory? Continental drift theory (CDT): Alfred Wegener found all the continents were once together called Pangaea (1 Earth / Land)
What proof did he have? Proof: 1) Continents fit together like a puzzle The following then match: 2) Mountains 3) Rock types 4) Plant fossils (Glossopteris) 5) Animal fossils (Mesosaurus) 6) Glacial deposits 7) Past climates
Laurasia (Northern Half) Panthalassa (All Sea s) Gondwanaland (Southern Half) Pangaea's first split was North and South (like the U.S.)
How long ago was Pangaea last together. Pangaea was last together 250 Million Years ago What did Wegener think caused the continents to break up? Wegener could never show how it broke up, he thought they floated apart on the ocean like boats on the water (they drifted with help from waves/tides)
WHAT SCIENTISTS HAVE DISCOVERED REALLY HAPPENED.
CDT LAB Purpose Learn about Continental Drift Theory Data Map of Pangaea (label its parts) 10? s Con What is CDT (continental drift theory)? Research Wegener (finrtd new info). Explain his proofs? What was Pangaea? (give its parts: Northern, southern, large ocean) How long ago was it last together? What was Wegener missing?
WHAT HAPPENS IF WE PLOT EARTHQUAKE LOCATIONS
What did plotting Earth Quakes show? Plotting Earth quakes revealed the Earth was not 1 solid outer crust. It is made of plates. (Most Earthquakes appear at plate boundaries, so do volcanoes) What are plates? Plates are Large broken up pieces of the Earths crust (Lithosphere). ~ 8 major plates and several minor
HOW TO FIND GERMAN U BOATS?
OTHER DISCOVERIES Zebra banding: Iron acting as a compass in rock shows the North and South poles have been flipping. They also appear in a matching pattern on both sides of the Atlantic
HOW ELSE CAN YOU FIND A SUBMARINE
Using Sonar a Large Volcanic Mt. Range is found to run down the center of the Atlantic. (Mid Atlantic Ridge) Rock close to the ridge (in the center of Atlantic) are youngest. Far rocks (on both sides by the continents S. America/Africa) are 250 million years old.
How can this be explained. Sea floor spreading: theory by Hess (A geologist in the Navy) that the Sea floor is young rock <250 million years old. Rock is getting created in the center at the Mid Atlantic Ridge and is being pushed outwards. This is growing the Atlantic Ocean. Sea floor spreading proves the plates are moving apart
How do plates move? Plates move due to convection currents in the mantle.
Why do Continents move? Continents move because they ride on top of the plates.
PLATE TECTONICS Putting all this new information together? Plate tectonics is the movement of Earths Plates and what happens at their boundaries. It is CDT + Plates + Sea Floor Spreading
What are the layers of the Earth called?
What are the layers of the Earth called?
Layers of the Earth. 1) Core (center): 2 parts A) Inner core (Solid Iron and Nickel) B) Outer core (Liquid Iron and Nickel) 2) Mantle: flowing molten (melted) rock Convection currents move mantle around Magma molten rock below ground Lava molten rock above ground
2B) Asthenosphere upper part of the mantle, called plastic mantle because it flows like heated plastic (continents ride on this) 3) Lithosphere The crust & Rigid Mantle (Top of mantle) Ocean crust Basalt (bass, salt) d= 3.0g/cm3 Continental crust Granite (counter tops) d=2.7g/cm3 Ocean crust is more dense
http://www.youtube.com/watch?v=qdqskltcixa
THE EARTHS INTERIOR What clues do we have about the inside of the Earth if we have never been down there? To infer about the interior of the Earth we use: 1) Meteorites: They are made of Iron, Nickel and Rock. If we started from the same materials we should have iron, nickel and rock. *Shows composition (What we are made of)
2) Earthquakes Earthquakes send seismic waves through the Earth. Based on their actions, we can infer a solid and liquid core. (acts like an x-ray) *shows state of matter
3) Lava. By studying lava you are studying material that was inside the Earth. *shows hot interior (and some composition)
TYPES OF PLATE BOUNDARIES How can plates move in relation to one another. Plates can move in 3 ways to each other 1) Divergent divides or moves apart 2) Convergent Comes together 3) Transform/Translate Slide past each other
DIVERGENT BOUNDARIES What are divergent boundaries?
DIVERGENT BOUNDARY
What happens at a Divergent Boundary? At a divergent boundary: 1) Plates move apart 2) Plates grow (addition of Lava) 3) Ridges are pushed up (mountains) 4) Rift valleys are created (Rift ~ Ripped) These occur on continents too
What happens when a Denser Oceanic plate converges with a less dense continental plate?
CONVERGENT (OCEAN VS CONTINENT)
Oceanic Plate Destroyed
At Convergent boundaries: When an ocean plate collides with a continental plate, it goes under due to density. This creates a deep trench in the ocean where the plates meet. Coastal mountains form where the continental plate rides over and buckles. The subducted oceanic plate melts, creates magma and volcanoes form. The oceanic plate is destroyed.
CONVERGENT BOUNDARIES What happens when continental plates with the same Density crash? http://www.youtube.com/watch?v=lofxyshxtf0& feature=related
CONVERGENT (CONTINENT VS CONTINENT) When 2 continental plates with the same density converge they buckle up and make mountains like the Himalayas, (Everest is where India collided).
What happens when 2 ocean plates converge?
If oceanic plates crash, they build volcanic island chains called Island arcs.
TRANSFORMATION Transformation Transform (translation) boundaries are when plates slide past each other. Rotation Turn! Reflection Flip! Translation Slide!
What happens when plates slide past each other?
Plate 1 Plate 2
Don t draw this slide! What will happen when these plates move?
After movement, land forms no longer match up.
What will happen if the plates can not slide easily past each other? Earthquakes happen when plates slide too fast and violently.
Transform Boundaries: Places where plates slide past each other. Many plates slide slowly past each other unfelt. Over time land forms may no longer match up. If plates get stuck, they will build pressure until they slip violently and create an Earthquake (Ex. California San Andreas Fault).
3 ways plates move? Plates move by C.D.T. (convergent, divergent, transform) What happens at Convergent Boundaries? Convergent Boundaries: Plates crash, Mountains, Ocean Plate destroyed, Deep ocean Trenches, Volcanoes. What happens at Divergent Boundaries? Divergent Boundaries: Plates move apart, new ocean plates created, Mid Ocean Ridges, Rift Valleys. What happens at Transform Boundaries? Transform Boundaries: plates slide past each other, Earthquakes.
http://www.youtube.com/watch?v=qdqskltcixa