continental drift
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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 . - PowerPoint PPT PresentationTRANSCRIPT
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