1. Pieces of a Puzzle

2. Law Theory Tells you exactly what to expect in certain situations
Newton’s Laws of Motion
Theory
An explanation that ties together many hypotheses and observations.
It is based on scientific evidence.

3. Theory of Continental Drift
***add to comparing and contrasting foldable**
Proposed by Alfred Wegener in 1915
He suggested that the continents were once joined together as one “supercontinent.”

4. The Theory of Plate Tectonics
the Earth’s lithosphere is divided into tectonic plates that move around on top of the asthenosphere
continents move at a rate of 2cm per year or about 1 inch year

5. Comparing the Theories (“Both” on the foldable)
Continents move
Earth was once made up of one large continent
Same evidence proves the theories
fossils
puzzle pieces
glacial deposits
mountain ranges

6. Pangaea “all land” The name of the one supercontinent
All continents joined together as one large land mass

7. What? – Theory of Plate Tectonics
Alfred Wegener
His studies were the 1st exhaustive research on the topic
He compiled evidence from many disciplines
His theory/hypothesis was not accepted by many scientists
What? – Theory of Plate Tectonics
It did not seem possible that the crust could move in that way
Finally accepted with discovery of sea floor spreading in the 1960s

8. When? 245 mil yrs ago: Pangaea 180 mil yrs ago: Laurasia & Gondwana
65 mil yrs ago: continents continue to separate
1620: Alfred Bacon – puzzle
1858: Snider-Pellegrini - fossils
1910: Frank Taylor - geological
1915: Wegener – put it all together
1960: seafloor spreading

9. Where?
continents and oceans
lithosphere and asthenosphere

10. Evidence of Continental Drift
Shapes of continents and the way they appear to fit together like pieces of a puzzle
Similar rock structures found on different continents
(highlight: locations of different types and ages of rock)

11. More Evidence of Continental Drift
Fossils found on different continents
(highlight: matching fossil remains)
Glacial till deposits of same age and type found on different continents
(highlight: glacial deposits)
Matching mountain belts located on different continents
(highlight: matching mountain belts)