Continental Drift

Continental Drift

What is continental drift?

What is continental drift?

1912 Alfred WegenerHypothesized that-• the continents are

moving= Continental drift

• all continents once formed a supercontinent = Pangaea

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 #1) S. America’s east coast fits like

a puzzle piece withAfrica’s west coast

Look at the bottom picture.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 line

(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

Where are fossils of the fern, Glossopteris, found? (lighter colored area below)

(Evidence #4) Africa and South America have

the same fossils

How is the fossil evidence useful for proving Continental Drift?

How do we know that continents are pushed apart?(Evidence #5) Seafloor spreading

at mid-ocean ridges (1962 H. Hess)

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 14 smaller ones

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.Continents

North America EurasiaSouth America AntarcticaAfrica IndiaAustralia

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

review1Summarize Alfred Wegener’s continental drift hypothesis2Note evidence that Wegener used to support his hypothesis:

Fit of continents, fossil evidence, rock types & structures, climate evidence

3Why was Wegener’s hypothesis rejected by the scientific community

4what new evidence was found to support Wegener’s hypothesis 2pts

5how does the new theory of plate tectonics explain continental drift

6make a sketch to show how divergent plate boundaries are formed

7paleomagnetism

What is continental drift?

1912 Alfred WegenerEvidence shows that-• the continents are

moving= Continental drift

• all continents once formed a supercontinent = Pangaea

What pushes continents apart? Mid-ocean ridges, AKA seafloor spreading

(1960 H. Hess)• Seafloor mountains

with a steep, narrow valley running down its center

• Crust near the ridge is very young

• Crust furthest from the ridge is oldest

How do we know that continents are pushed apart?(Evidence #5) Seafloor spreading

at mid-ocean ridges (1962 H. Hess)• Ocean rocks are

younger (or newer) than continental crust

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