Continental Drift. The idea that the world s land masses are slowly moving over time

Alfred Wegener

Continental Drift The idea that the world s land masses are slowly moving over time

Pangaea The supercontinent made of all continents that existed millions of years ago.

Present Cretaceous Period Permian Day Age Triassic Jurassic Age 65 mya 225 mya 200 135

Alfred s Evidences 1. Geometric Evidence

Alfred s Evidences 1. Geometric Evidence The continents appear to fit together like pieces of a puzzle

2. Fossil Evidence Mesosaurus Cynognathus Glossopteris Distribution of Cynognathus Distribution of Glossopteris Distribution of Mesosaurus

2. Fossil Evidence Fossils of some species are only found on the matching coastlines of continents now separated by oceans

3. Mountain Evidence

3. Mountain Evidence I never really liked him anyways I miss my friend ATLANTIC OCEAN

3. Mountain Evidence Mountain ranges end on one coastline and pick back up on another. The rock patterns of these mountains match up.

Before Matching rock patterns After

4. Climate Evidence Deposits of coal prove that tropical plants used to grow in cold areas like Antarctica...

... and evidence of past glaciers is found in places that are too hot today. Pangaea

... and evidence of past glaciers is found in places that are too hot today.

Alfred s Evidences 1. Geometric Evidence 2. Fossil Evidence 3. Mountain Evidence 4. Climate Evidence REJ ECT ED

The problem Despite all of his evidence, Wegener could not explain HOW it all happened. To Be In other words, he had d e u n i t n Co No Mechanism!

Recap When we last left, poor Alfred s hypothesis of continental drift was being rejected by his fellow scientists REJ ECT ED

HYPOTHESIS VS. THEORY Provides Evidence Provides Evidence Cannot explain HOW Provides a mechanism (the how )

World War II Sonar using sound waves to determine Finally able to map the ocean floor! depths and sizes of objects

Mid-Ocean Ridge A long underwater mountain range where magma comes up from the mantle

Harry Hammond Hess Geologist and U.S. Naval Officer He came up with the idea that the continents move because the ocean floor is getting wider

MY UNDERWATER RESEARCH FACILITY M.U.R.F.

Seafloor Spreading The seafloor slowly grows outward from This is the MECHANISM of continental drift! mid-ocean ridges as new crust is formed, pushing the continents along for the ride. 20 million 15 10 million million 5 million Present years years later years later later years later Day

Somewhere in Greenland Alfred Wegene r R.I.P.

Youngest rocks

Next Youngest rocks

1. The Age of Ocean Rocks Evidence of seafloor spreading The fact that rocks get older at equal rates the farther away you get from a mid-ocean ridge is evidence of seafloor spreading

+ N E W S -

+ + + N E W - - S - + + + + - + + - - + - - - - + + - - - - + - + + + + - -

N E W S

++ ++ -- - + E -- + - + + + - + ++ - - -- + - - + - ++ ++ - - + - - + + + - + + + + + - - + S + - + - N W - + ++ -- - -

+ + + N E W - - S - + + + + - + + - - + - - - - + + - - - - + - + + + + - -

N E W S

Evidence of seafloor spreading 2. Magnetic Striping The fact that magnetic stripes on the ocean floor are identical on both sides of a mid-ocean ridge is evidence of seafloor spreading

Let s draw a diagram Mid-Ocean Ridge Younger Younger rocks rocks Older rocks - + - New rocks form at the ridge pushing old rock away + + - + - Older rocks

Quiz Time

Quiz Time Alfred s Evidences 1. Geometric Evidence 2. Fossil Evidence 3. Mountain Evidence 4. Climate Evidence

Quiz Time Why was Alfred Wegener not accepted in his time?

Quiz Time

Quiz Time What is the mechanism of continental drift?

Quiz Time Who came up with the mechanism of continental drift?

Quiz Time Where does seafloor spreading take place?

Quiz Time Seafloor spreading is what causes the continents to move. To Be What evidence do we have that seafloor d e u n i t n Cois actually occurring? spreading

DRIVING FORCES OF PLATE Movement 1. Convection

Convection Cycle where substances rise and fall because of changes in temperature and density. Examples: magma, water, air

Becomes More Dense Gets Cooler Molecules Condense & Sink Molecules Spread & Rise Gets Hotter Becomes Less Dense

Convection moves the plates by rolling them along like a conveyor belt

DRIVING FORCES OF PLATE Movement 1. Convection 2. Gravity

Gravity Force that pulls objects towards the Earth

Gravity moves plates by pulling them down at subduction zones

DRIVING FORCES OF PLATE Movement 1. Convection 2. Gravity 3. Pressure

Pressure Force that pushes outward against the space around it

Pressure moves the plates as rising magma pushes at the mid-ocean ridge.

DRIVING FORCES OF PLATE Movement Let s Strongest Draw a 1. Convection diagram! Still strong Kind of weak 2. Gravity 3. Pressure

Finally, we re ready to learn about... PLATE TECTONICS! ` Gravity Pressure Convection Convection Gravity

Earth s outer shell is broken up into chunks called Plates

Plate Tectonics The theory describing how Earth s plates move and what happens when they interact with each other.

Lithosphere Crust Asthenosphere Mantle Outer Core Inner Core The fluid The conveyor belt Plates

crust lithosphere asthenosphere mantle

Lithospher e crust mantle Asthenosphere

Lithospher e Asthenosphere

Lithosphere Asthenosphere Crust Mantle Outer Core Inner Core The fluid The conveyor belt Plates

Two kinds of crust Ocean Crust Ocean Crust Continental Crust Continental Crust

Ocean Crust Continental Crust Thinne r More Thicke r Less Dense Younger Dense Older Ocean Crust Continental Crust

TRU E True or False A single plate can have both oceanic and continental crust To Be d e u n i t n Co

Three types of plate boundaries

Three types of plate boundaries Woot

Convergent

C stands for Convergent Crash Crunch Blearghh Combine gsdrjdnu Gragh! ioqwah! Collide

Convergent The plates crash together Three Kinds: Forms different Land stuff depending Land on which type of Ocean collision you have VS Land VS Ocean VS Ocean

Type of Boundary Definition Convergent Continental crust collides with continental crust (Land vs. Land) What it creates Continental crust collides with continental crust Picture

Type of Boundary Definition Convergent Continental crust collides with continental crust (Land vs. Land) What it creates Picture

Mountains

Mountains Earthquakes

Type of Boundary Convergent (Land vs. Land) Definition What it creates Two plates with continental crust collide Mountains Earthquakes Convergent Continental crust collides with (Land vs. Ocean) oceanic crust Continental crust collides with oceanic crust Picture ` `

Type of Boundary Definition What it creates Convergent Continental crust collides with continental crust Mountains Earthquakes (Land vs. Land) Convergent Continental crust collides with (Land vs. Ocean) oceanic crust Picture ` `

Mountains

Mountains Subduction Zones

Mountains Volcanos Subduction Zones

Mountains Volcanos Trenches Subduction Zones

Mountains Earthquakes Volcanos Trenches Subduction Zones

Volcano Trench Subduction Zone

Trenches

Island Arcs Can t really get the whole picture with a side view Trenches

Island Arc Trench

Island Arcs Trenches Subduction Zones

Earthquakes Island Arcs Trenches Subduction Zones

Type of Boundary Definition What it creates Convergent Continental crust collides with continental crust Mountains Earthquakes (Land vs. Land) Volcanoes Convergent Continental crust Trenches collides with Earthquakes (Land vs. Ocean) oceanic crust Subduction Zones Convergent (Ocean vs. Ocean) Divergent Oceanic crust collides with oceanic crust Island Arcs Trenches Earthquakes Subduction Zones Picture ` `

Divergent Boundary

D stands for Divergent Boundary Divide Distance Dash Away Donuts

Type of Boundary Definition What it creates Convergent Continental crust collides with continental crust Mountains Earthquakes (Land vs. Land) Volcanoes Convergent Continental crust Trenches collides with Earthquakes (Land vs. Ocean) Two plates away from oceanic crustmove Subduction Zones Convergent each other Island Arcs Oceanic crust (usually ocean Trenches crust) (Ocean vs. Ocean) collides with oceanic crust Divergent Two plates move away from each other - usually ocean crust Earthquakes Subduction Zones Picture ` `

Type of Boundary Definition What it creates Convergent Continental crust collides with continental crust Mountains Earthquakes (Land vs. Land) Volcanoes Convergent Continental crust Trenches collides with Earthquakes (Land vs. Ocean) oceanic crust Subduction Zones Convergent Two oceanic (Ocean vs. Ocean) crusts colliding Divergent Two plates move away from each other - usually ocean crust Island Arcs Trenches Earthquakes Subduction Zones Picture ` `

Divergent Boundary Mid-Ocean Ridge

Type of Boundary Definition What it creates Convergent Continental crust collides with continental crust Mountains Earthquakes (Land vs. Land) Volcanoes Convergent Continental crust Trenches collides with Earthquakes (Land vs. Ocean) oceanic crust Subduction Zones Convergent Two oceanic (Ocean vs. Ocean) crusts colliding Divergent Transform Island Arcs Trenches Earthquakes Subduction Zones Two plates move Mid-Ocean Ridges away from each Seafloor Spreading other - usually Earthquakes ocean crust Picture ` `

Transform Boundary

Type of Boundary Definition What it creates Convergent Continental crust collides with continental crust Mountains Earthquakes (Land vs. Land) Volcanoes Convergent Continental crust Trenches collides with Earthquakes (Land vs. Ocean) oceanic crust Subduction Zones Island Arcs Trenches Two oceanic Earthquakes (Ocean vs. Ocean) crusts colliding Two platessubduction scrapingzones Convergent past eachmid-ocean other Ridges Divergent Transform Two plates dividing (usually Seafloor Spreading Earthquakes ocean crust) Two plates scraping past each other Picture ` `

San Francisco L.A. San Diego

San Andreas Fault San Francisco L.A. San Diego

San Francisco L.A. San Diego

Type of Boundary Definition What it creates Convergent Continental crust collides with continental crust Mountains Earthquakes That (Land vs. Land) Picture ` Volcanoes Convergent Continental crust Trenches collides with Earthquakes (Land vs. Ocean) oceanic crust Subduction Zones is Convergent a Two oceanic (Ocean vs. Ocean) crusts colliding Divergent Transform Island Arcs Trenches Earthquakes Subduction Zones Mid-Ocean Ridges Two plates dividing (usually Seafloor Spreading Earthquakes ocean crust) l u f i t u a be Two plates scraping past each other Table Earthquakes `

Random?

Most of the world s volcanoes and earthquakes happen at plate boundaries, especially convergent boundaries

Ring of Fire

Hotspot

Hotspot Can t really get the whole picture with a side view

Island #1

Island #1 Island #2

Island #1 Island #2 Island #3

Island #1 Island #2 Island #3 Island #4

Hotspot A location that is volcanically active even though it is not located near a plate boundary

Quiz Time What are the three driving forces of plate movement?

Quiz Time How does convection move the plates?

Quiz Time How does gravity move the plates?

Quiz Time How does pressure move the plates?

Quiz Time What is the lithosphere?

Quiz Time What is the asthenosphere?

Quiz Time Which type of crust is younger, thinner, and more dense? Oceanic or continental

Quiz Time a. c. b. d.

Quiz Time Trench mid-ocean ridge

Mid-Ocean B Ridge A Trenc h Pressure E D D F Gravity Convection C Subduction Zone

Quiz Time Where do most of the world s earthquakes and volcanoes occur?

Quiz Time What do you call a place that is volcanically active even though it is not located near a plate boundary?

THE END! Alfred Wegene r R.I.P.