Plate Tectonics Continental Drift Alfred __________ (1912) German __________

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Plate Tectonics
 Continental Drift
 Alfred __________ (1912)
• German __________
• __________ moved slowly to their current locations.
• __________- the single landmass of Earth that broke apart about 200mya . “All Land”
 Evidence

__________-like Fit
• __________s of continents fit together like puzzle pieces.
• Examples: S.America & __________

Fossil Clues
• Certain __________ of ancient animals & plants are found on distant landmasses.
• Freshwater/land-dwelling reptile Mesosaurus fossils have been found on _______________& Africa.

__________ of the ancient plant Glossopteris were found in __________, South America, Australia, India,
& Antarctica.

__________ Clues
-Fossils of warm climate plants were found in present-day cold climates. (__________
-Rocks deposited by __________ from the ice ages have been found in present-day warm climates.

Rock Clues
• Similar rock structures are found on different continents separated by __________.
-Appalachian mountains of the USA are similar to mountains found in __________& western Europe
-Rocks of South America match those in __________
Main __________ to Wegener’s hypothesis was its inability to provide a __________ for the movement of
the continents.
 __________ Spreading
 Hypothesis
__________ waves were used to map the ocean floor.
Mid-ocean Ridges- __________ mtn ranges
 Less dense __________flows sideways dragging the seafloor along.
 As the seafloor spread apart, magma flows up through __________ in at the ridge forming new rock.

•
Evidence
__________ - Ocean floor rock samples show that the age of the rock gets older the further the rock is
from the mid-ocean ridge
•
__________ -Changes in the magnetic alignment of the Earth are found in __________ bands in the
seafloor rock.

Theory of Plate Tectonics
Combined theory of __________ Drift & Seafloor Spreading.
Earth’s crust & upper mantle (__________) are broken into plates and move around on a
__________-like layer of the mantle (__________.)

Seven major plates:
__________ (largest)
N. American
S. American
African
Eurasian
__________
Antarctic
Plate Boundaries

__________ Boundaries
 Two plates spread apart.
 Where __________ spreading occurs.
 __________ crust is formed. Ex: Mid-Atlantic Ridge
•
__________ Boundaries
– Two plates come together (__________
– Oceanic plate will sink under a continental plate (__________) producing a deep __________.
Ex:
__________ & Cascades
– Two oceanic plates will converge resulting in a __________ island arc.
•
Ex: __________ Islands
__________ Fault Boundary
– Two plates slide past each other.
– Move at __________ rates.
– Also known as __________slip faults. Ex: San Andreas Fault

Causes (__________)
• __________ Currents
– Hot magma rises in the __________.
– Magma hits the __________ & cools.
– Cooling magma sinks dragging the ____________________ plate with it (centimeters.)
– Magma sinks into the mantle & __________.

Features Formed by Tectonics
•
__________
•
–
Cracks in the tectonic plates caused by __________.
–
Plate __________ are also faults.
–
Movement along faults cause __________.
Volcanoes-Magma produced by friction during __________ oozes up through the crust, __________, &
forms volcanoes.

__________
•
Convergent & Divergent boundaries form __________.
•
Process of mountain building is called __________.
-Volcanic Mountains
•
__________ Mountains
o
Horizontal rock layers are squeezed from opposite sides, causing them to __________ & fold.
EX: ____________________ & Appalachians
•
__________-block Mountains: Huge, tilted blocks of rock that are separated by __________. EX: Sierra
Nevada
•
__________ Mountains- blocks of Earth’s crust are pushed up by __________ inside the Earth.
(__________) EX: __________ Mountains