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 

How do South America and Africa fit together. (Evidence #1) S How do South America and Africa fit together? (Evidence #1) S. America’s east coast fits like a puzzle piece with Africa’s west coast 4

How do South America and Africa fit together. (Evidence #1) S How do South America and Africa fit together? (Evidence #1) S. America’s east coast fits like a puzzle piece with Africa’s west coast 5

Look at the bottom picture Look at the bottom picture. What do you notice about the mountains in North America and Europe? 6

Look at the bottom picture Look at the bottom picture. What do you notice about the mountains in 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 7

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 and South America have the same fossils 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 How do we know that continents are pushed apart? (Evidence #5) Seafloor spreading at mid-ocean ridges (1962 H. Hess) 11

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 12

How many tectonic plates are there How many tectonic plates are there? Scientists have identified 7 major plates and 14 smaller ones

How many tectonic plates are there 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 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 Sequence A. 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 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

review 1Summarize Alfred Wegener’s continental drift hypothesis 2Note 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 Wegener Evidence shows that- the continents are moving = Continental drift all continents once formed a supercontinent = Pangaea

What pushes continents apart 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 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 24