Warm-Up
Warm-UpIf a bone specimen contains 12.5% of its original amount
of Carbon-14, how many half lives have passed?How old if the
bone?
Times Up!
Evidence of Continental DriftMaking InferencesObservation:
Information that can be collected using your senses.Inference: a
conclusion made based on observations.
Today we will be EVALUATING evidence of continental drift. Take
2 minutes to observe the world map. One observation I would make is
that the coast lines are uneven rather than smooth and straight.
Make 2 more observations about the continents coast lines. Make 1
inference based on your observation
EndContinental DriftPuzzle (2 minutes)Work with your partner to
try and fit the continent puzzle pieces together.
EndContinental DriftDo they fit together perfectly?What may have
caused the coastlines to change over time? Come up with 2 possible
reasons (2 minutes)
EndContinental DriftLook at the small pictures on your puzzle
pieces. Those are fossils found in those areas of each continent.
Rearrange your puzzle so that all of the fossil segments line up.
(3 minutes)Make 3 observations (the same fossils are on more than
one continent)Make 1 inference
EndEarthquakes
Volcanoes
End
Plate TectonicsPlates = divisions of lithosphereMoving on
asthenosphereContinental DriftContinental Drift: The continents are
moving.
History of Plate TectonicsAlfred Wegener hypothesized in 1912
that continents were slowly drifting around the Earth.
11Wegener Continental Drift TheoryEarly 1900sOnce single
landmass - Pangaea
Broke up Laurasia, GondwanaDrifted to present location
Evidence of Continental DriftThe continents fit together.
Evidence of Continental DriftFossils of the same animals are
found along the coasts of different continents.
Evidence of Continental DriftSeismic, volcanic, and geothermal
activity along plate boundaries.
How would you explain this evidence?4. Sea-Floor Spreading
Mid-ocean ridgesTectonic plates moving separatingNew magma
risesForm new oceanic crustOlder crust pushed away5. Magnetic
ReversalsMolten rockMagnetic mineralsAlign with magnetic
fieldMagnetic field reverses177 times in 85 million yearsLast
600,000 years agoRecorded in rockSimilar pattern to age of
rocks
Cause of Continental DriftConvectionAsthenosphereHeated rock
Expands and risesCoolsMore dense
Pangaea300 million years ago scientists believe that all of
Earths landmass was together in one single supercontinent. Over the
past 300 million years the continents have spread apart from each
other.
