Download ES Ch 1 NOTES Plate Tectonics

Name___________________________________________
CHAPTER 1 NOTES PACKET
Date__________________
1.1 EARTH HAS SEVERAL LAYERS
A) Earth is made up of materials with different____________________________________________.
1) About ________ billion years ago the Earth formed from explosions from
comets and asteroids, which along with heat and pressure, turned the Earth
into a ball of glowing, melted rock.
2) Over time the materials sank to the center of the Earth and less _______________
material moved towards the surface, forming the Earth’s layers.
B) Earth’s layers have different properties.
1) The Earth’s layers vary in composition, _________________________________ and
thickness.
2) The Earth’s crust and top of the mantle form the _______________________________
or “rock” layer of the Earth.
3) Below that is the ____________________________, softer rock in the upper mantle
called the asthenosphere, which is like hot tar.
a) Crust is cool ___________________, 0-700C
and 6-70km thick. It’s thinnest under
oceans and thickest under continental
mountain ranges.
b) The mantle is _____________________________
rock, 870-4400C and 2900km thick. It’s
like hot, thick paste.
c) The outer core is __________________________
metals, 4400-6100C and 2300km thick.
d) The inner core is __________________________
metals, 7000-8000C and 2400km in
diameter.
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C) The lithosphere is made up of many _________________________________.
1)
It is split into random slabs of rocks called _______________________
plates, which fit together like puzzle pieces.
2)
Most of the ___________________ plates contain both continental and
oceanic crust.
3)
These plates have help to solve the mystery of how continents moved to
their present position.
1.2 CONTINENTS CHANGE POSITION OVER TIME
A) Continents join together and _______________
apart.
1) Alfred Wegner proposed a
_________________________________ on
continental drift in the early 1900’s.
2) He stated that the Earth’s
continents were once ______________________
as a single landmass and then slowly moved
apart.
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3) Fossil Evidence- fossils of many ____________________________________
creatures have been found on opposite shores, like the Mesosaurus.
4) Coal in Antarctica- coal is formed in _______________________
swamps, from the remains of vegetation that grew as long as
400 million years ago.
5) Geology- Rock layers found in on the _______________________
of one continent may be the same as rock layers on other
continents.
B) The theory of _____________________________________________________ explains how plates
and their continents move.
1) Wegner’s ideas were pushed aside for many years until scientists realized that
plate tectonics could connect some of his concepts.
2) In the __________, scientists created
maps of the sea floor and noticed
that there were underwater mountain
ranges called mid-ocean ridges.
3) _____________________________________
is when melted rock rises through
cracks in the crust and pushes old
crust over as new crust rises.
4) The __________________ crusts oldest
age is between 160-180 million
years old and the continental crust
is around 4 billion years old.
5) Ocean trenches are deep canyons where _____________________________ oceanic
crust allows old crust to sink back into the asthenosphere. Old crust is
destroyed as quickly as new crust is formed.
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C) Plates move because of ______________________________________ currents in the
asthenosphere, which allows hot, soft rock to rise, it then cools and sinks, then it’s
heated and rises again.
1) This plate movement causes major earthquakes, volcanoes and mountain
ranges to appear.
Most of the world's active volcanoes (triangles) are along the edges of tectonic plates
(the lines).
1.3 PLATES MOVE APART
A) Tectonic plates have different __________________________________________.
1) Convergent Boundariesplates _______________________
into each other.
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2) Divergent Boundaries- plates
spread apart
3) Transform Boundaries- two _______________ slide past each other.
This picture (LEFT) shows the San Andreas Fault in California, which is a transform fault. The aerial view (RIGHT) of the
San Andreas Fault (transform) the trees in the orchard (dots) have been offset by the slipping of the plates. The Pacific Plate is
to the left and the North American to the right.
B) The sea floor spreads apart at ________________________________________ boundaries, which
are at mid ocean ridges and rift valleys.
1) Mid ocean ridges form the
longest _____________________________
chains on Earth and most contain
a rift valley in the center.
2) Magnetic reversals have
occurred ___________________________
times over the Earth’s long history.
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a) Bits of _______________________ in lava will tend to line up with a magnetic
orientation pointing at the North Pole. When the lava solidifies, the
magnetic orientation is frozen into the rock- essentially; it will have a
“north end” and a “south end” on the ocean floor.
C) Continents split apart at _______________________________________ plate boundaries.
1) Divergent plate boundaries on continents also produce rift valleys.
Great Rift Valley of Africa
a. Magma rises through cracks to form ____________________________________
and as the rift valley grows wider, the continent splits apart.
b. The valley floor slowly thins and _______________________ until
eventually it’s below sea level.
c. Water from nearby _____________________________ or rivers may fill the
valley and form a sea or lake.
D) Hot spots can be used to track ___________________________________ movements.
1) Hot Spots are areas of
___________________________________
activity that develop where magma
rises in a plume from the mantle.
2) The _________________________________
plume acts like a blowtorch while
the plate moves above it.
Hawaii is an example of a hot spot island chain.
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1.4 PLATES CONVERGE OR SCRAPEPAST EACH OTHER
A) Tectonic plates ______________________________________________ at convergent boundaries.
1) _______________________________________-continental collision occurs where two
continental plates collide, crumpling and folding rock between them.
The collision of India into Asia 50 million
years ago caused the Eurasian Plate to crumple up and override the Indian Plate creating the
Himalayas and the Tibetan Plateau
2) _______________________________________-oceanic subductions occur when two
oceanic plates collide and the older, denser plate sinks beneath the top plate,
forming deep ocean trenches and island arcs.
The Mariana’s Trench, for example, is a deep
trench created as the result of the Philippine Plate subducting under the Pacific Plate.
3) ______________________________________-continental subduction occurs where an
oceanic plate sinks beneath a continental plate, forming a deep ocean trench
and volcanic coastal mountains.
Off the coast of South America along the Peru-Chile trench, the oceanic Nazca Plate is subducting under
the continental part of the South American Plate. In turn, the overriding South American Plate is being
lifted up, creating the towering Andes Mountains.
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B) Tectonic plates _______________________________ past each other at transform boundaries.
1) At transform boundary,
two plates move past
each other in opposite
directions and their edges
scrape and grind against
each other.
2) __________________________is
formed or destroyed and
it occurs both on land
and the sea floor
The San Andres Fault in California is an
example.
C) The theory of plate tectonics helps geologists today.
1) This allows geologists to understand how _____________________________
and ocean basins formed.
2) Geologists can also __________________________ earthquakes and volcanic
activity.
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