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Aim: How does the Theory of Plate
Tectonics influence the way the Earth is
today?
I. Plate Tectonics
A. Theory of Plate Tectonics
1. The surface of the Earth is composed of
about a dozen major rigid, moving crustal
plates and several smaller plates
1.Plates
a. Slabs of Earth’s lithosphere (crust and upper
mantle)
b. Average thickness is 100 km (62 miles)
c. Most plates support both continent and ocean
B. Continental Drift – states that the
continents have drifted and still are drifting
apart.
C. Why do the plates move?
1. Due to tremendous heat, rock in the
asthenosphere is like hot taffy
2.This allows plates to ride on top of hot,
flowing rock.
3. Plates move because heat is being released
from deep inside the earth.
4. Convection currents causes hot material to
rise and expand (plates diverge) and cooler
material to sink and contract (plates
converge).
Alfred Wegener
D. Alfred Wegener – proposed that in the
distant past, the Earth’s continents were all
joined as a single landmass.
1. Evidence for his theory
1. South America and Africa would fit
remarkably well, shoreline to shoreline.
2.If the Americas were moved next to Africa
and Europe, there would be a match of
ancient continental rocks and tectonic (fold
and fault) structures.
c. Pangaea – when Wegener placed all the
continents together like a puzzle, it formed a
large landmass which he called Pangaea.
Fossil Evidence
Plate Boundaries
• http://geology.com/nsta/divergent-plateboundaries.shtml
• http://www.iris.edu/hq/programs/education_and_
outreach/animations/11
• http://www.classzone.com/books/earth_science/t
erc/content/visualizations/es0804/es0804page01.
cfm?chapter_no=visualization
Plate Puzzle Activity
• Task:
• With the bag of puzzle pieces place them
together so that is forms a rectangular
map.
• Work together as a table group.
On a separate sheet of paper answer the following question. Answer
each question in COMPLETE SENTENCES. You may use Chapter 3 in
the blue “Dynamic Earth” book as a reference.
1. What are the major features that correspond to the plate boundaries?
2. Compare the picture of earthquakes on page 61 with the map on page 65. How are
they similar? What is a possible explanation for this?
3. What plate is North Carolina located on?
4. Who is Alfred Wegener? What did he discover?
5. Which plate is the largest?
6. What kinds of evidence are used to support the theory of continental drift?
7. Describe the three different types of plate collisions.
8. What is ocean-floor spreading? How does it relate to the theories of continental
drift and plate tectonics?
9. How do you think living organisms have been affected by the movement of plates
throughout Earth’s history? (hint page 73)
10. Create a Venn Diagram between the concepts: Plate Tectonics and Continental
Drift