continental drift. what is continental drift? 1912 alfred wegener hypothesized that- the continents...

Continental Drift

What is continental drift?

What is continental drift?

1912 Alfred Wegener

Hypothesized that-• the continents are

moving

= Continental drift

• all continents once formed a supercontinent

= Pangaea

Many pieces of evidence suggest that Pangaea existed…

How do South America and Africa fit together?(Evidence #1) S. America’s east coast fits like

a puzzle piece withAfrica’s west coast

How do South America and Africa fit together?

Evidence #1South America’s east coast fits like a puzzle piece withAfrica’s west coast.

Look at the two images.What do you noticeabout the mountainsin North America and Europe?

Look at the bottom picture.What do you noticeabout the mountainsin North America and Europe?The Appalachian Mtns. (USA) and the mountains in Europe once formed a single mountain range.(Evidence #2) The type of rocks in different continents are similar

What can past climates tell us?

Evidence #3• Continents show past

changes in the climate

• Fossils of tropical plants in Antarctica, indicate a warmer, tropical climate at one time

• Rocks show that glaciers once formed on Pangaea

Evidence #4

Africa, South America, and Australia all have similar fossils

of the fern, Glossopteris.(lighter colored area below)

How is the fossil evidence useful for proving Continental Drift? (discuss & write)

How do we know that continents are pushed apart?

How do we know that continents are pushed apart?Evidence #5

Seafloor spreading at mid-ocean ridges (1962 H. Hess)• Rocks made in the

Atlantic Ocean are younger (or newer) than the continents

Here’s how we know this-

• Crust furthest from the ridge has older sea-fossils

• Patterns in iron crystals (paleomagnetism) indicate that ocean crust began forming less than 160 million years ago

How many tectonic plates are there? Scientists have identified

7 major plates and 14 smaller ones

How many tectonic plates are there? Scientists have identified

7 major plates and many smaller ones

Smithsonian

Where are volcanoes found?Write down one thing that you notice about where

volcanoes occur

Where are volcanoes found?Write down one thing that you notice about where

volcanoes occur

Evidence #6: Volcanoes and earthquakes near plates

When did Pangaea break apart? …During the Mesozoic Era, about 200 m.y.a.

Summary of evidence:#1 Continental coastlines fit together (Wegener)

#2 The type of rocks in different continents are similar (Wegener)

#3 Past changes in the climate can be explained by Continental Drift (Wegener)

#4 The same plant & animal fossils are found on different continents (Wegener)

#5 Seafloor spreading explains plate movement

#6 Volcanoes & earthquakes indicate plate movement

Handout- Continental Drift SequenceA. Color each continent the same color in each picture

of the sequence.

B. Identify each continent and label them.

C. On the back, describe what happens with the continents as time passes.

D. Draw a prediction of where they will be in the future.

ContinentsNorth America Eurasia

South America Antarctica

Africa India

Australia

resources

• http://www.plainedgeschools.org/swells/plate_tectonics.htm

• http://slohs.slcusd.org/pages/teachers/rhamley/Biology/Continental%20Drift/Tectonics.html

• http://geology.rutgers.edu/103web/Pangeabreakup/breakupframe.html

What is continental drift?

1912 Alfred Wegener

Evidence shows that-• the continents are

moving

= Continental drift

• all continents once formed a supercontinent

= Pangaea