Download Hemingway Name: 12.1 Evidence for Continental Drift * PANGEA

Hemingway
Name:
12.1 Evidence for Continental Drift
* PANGEA activity
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Early maps of the world caused Wegener to propose the __________________________
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The continents looked as though they might fit together like ___________
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The continental shelves actually fit together even better.
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The original supercontinent was named ___________by Wegener.
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Wegener also realized that other evidence also supported his theory.
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There were matching ________________ and rocks on different continents.
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There were matching ____________, like Mesosaurus, on different continents.
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________________ began on one continent, end on the coastline and
then appear to continue on a continent across the ocean
Found only in southeast South America and southwest Africa
There was evidence of different _______________ (eg. Such as glaciers) on
warm continents.
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When glaciers retreat they leave a mark (U-shaped valleys/scratched
rock)
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India/Africa which are now tropical had evidence of glaciers
How do Continents move?
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Wegener’s evidence for continental drift did not explain how entire continents could change
locations.
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New scientific equipment allowed scientists to measure the slow but steady drift of
Earth’s tectonic plates.
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It was noted that __________ and _________ appear in certain patterns along the
edges of tectonic plates.
Volcanoes are frequently found on boundaries between tectonic plates
How Can Continents Move?
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Mapping of the ocean floor revealed the ___________________, a long mountain range
running down the middle of the Atlantic Ocean.
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Rocks taken from the Mid-Atlantic Ridge were ___________ than other ocean rocks.
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Sediments along the ridge became thicker farther away from the ridge.
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Earth has a __________________magnetic pole and magnetic field
Hemingway
Name:
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Produced by motion of ___________ in the planets interior
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Magnetic reversal occurs when the magnetic field completely reverses
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North South, South North
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Does not affect the earths ______________________
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Has occurred __________times in the last 10 million years
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Ancient rock have preserved the direction of the magnetic field
______________________ is the study of magnetic properties of ancient rocks
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shows that iron-based rocks along the ridges are striped with reversing
magnetic fields.
Sea Floor Spreading: An Explanation
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Hess suggested that magma rose to form ___________ at certain places.
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Magma (melted rock) _____________ like warm and cold liquids.
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The convection currents of magma formed a _________________ where they broke
through Earth’s crust.
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Like a “new crust” conveyer belt
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Magnetic striping of basalt rock shows long stripes of new rock moving away
from ocean ridges and also reveals the direction of Earth’s magnetic field at that
time.
Wilson then unified the ideas of Wegener and Hess into the _________________________
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Continental drift occurs because of areas like these ridges that push along tectonic
plates floating on Earth’s surface.
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_______________________: the lithosphere is broken up into large plates that move
then rejoin
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Geologic ___________ are anywhere magma rises to Earth’s surface.
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__________________
Activity 12-1 B
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Sea floor spreading
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Workbook 210-213