Transcript EQ: How has the physical process of plate tectonics

EQ: How has the physical process
of plate tectonics effected Earth’s
surface?
Lesson 20
Pangaea Song and Lyrics
http://bmsscience8209.edublogs.org/2012/11
/05/week-of-october-25-convection-currentsin-the-earth/
Effects of Physical Processes
• Just as there was once a single great land
mass, there was also a single great ocean
around that land mass.
• The separate oceans we now know were
formed as the land masses separated.
• These separations produced amazing features
on the ocean floor, such as the longest
mountain range on Earth.
Plate Tectonics Part 1
• Many physical processes have shaped Earth’s
surface.
• The physical process of plate tectonics have
shaped Earth’s oceans.
• Plate Tectonics describes how Earth’s
lithospheric plates move and how their
movements shape Earth’s crust.
• The continents and ocean floor of Earth ride
on 13 lithospheric plates
Plate Tectonics, 2
• In the 1950s, scientists discovered that rocks on
the floor of the oceans were younger than rocks
on the continents.
• Harry Hess, an American geologist, suggested
that the sea floor was spreading. ( Divergent
Boundary)
• As it spread, from an opening in its middle,
magma from Earth’s mantle oozed from the
opening onto the surface of the ocean floor.
• When the magma came in contact with seawater,
it hardened into new rock.
Plate Tectonics
• This rock formed a huge mountain range that
snakes through all of Earth’s oceans.
• This undersea mountain range is called the
mid-ocean ridge. ( Divergent Boundary)
• As distance from the opening increased, the age
of the rocks also increased.
• Because the spreading has been constant
throughout history, the formation of the South
Atlantic Ocean can be traced back to a time when
South America and Africa were once part of the
same landmass.
Continental Divergent
A rift valley is a
linear-shaped
lowland
between two
continental
plates or
mountain ranges
that have
separated
(divergent).
A rift valley is formed on a divergent
plate boundary.
Location: Africa
Location: Turkey
Example of Sea-Floor Spreading
Animated Boundaries
• http://www.teachersdomain.org/assets/wgbh
/ess05/ess05_int_tectonic/ess05_int_tectonic
.swf
• http://www.classzone.com/books/earth_scien
ce/terc/content/visualizations/es0804/es0804
page01.cfm?chapter_no=visualization
• http://www.teachersdomain.org/asset/ess05_
int_shake/
Convection Currents 1:
Causes Plates to Move
• Lithospheric plates move due to convection
currents in Earth’s mantle.
• A convection current is a current formed by
heated liquid that moves along a circular path.
• Warm liquid moves upward and across a
surface because it is less dense.
• It cools at the surface, becomes more dense,
and moves downward.
• Then it warms again, becomes less dense, and
moves upward.
Boiling Water –
Convection Currents
Causes of Plate Movement
Convection Currents 2:
Causes Plates to Move
• As long as heat is applied from below, the liquid will
move around and around in convection currents
• Heat from Earth’s mantle sets up convection currents.
• These convection currents are made up of liquid rock.
• The liquid rock rises to a place under the lithospheric
plates.
• The currents move in opposite directions, pushing
plates apart in one place, and together in another
place.
Quick Check
Plate tectonics describe movements MAINLY in
A. Earth’s crust.
B. Earth’s mantle.
C. Earth’s outer core.
D. Earth’s inner core.
Quick Check
Which ocean was produced by seafloor
spreading between Africa and South America?
A. Pacific Ocean
B. Indian Ocean
C. North Atlantic Ocean
D. South Atlantic Ocean
Quick Check
As distance increases from a mid-ocean ridge,
the rocks
A. grow younger
B. grow older.
C. do not change in age.
D. become liquid.
Quick Check
Assume a sea floor has been separating at an
average rate of 5 cm a year. The sea is presently
8000 km wide. How long ago did the sea begin
to form?
A. 1,600 years ago
B. 40,000 years ago
C. 160,000,000 years ago
D. 4,000,000,000 years ago
Quick Check
A convection current of magma is made up of
A. a rising more dense liquid and a sinking less
dense liquid.
B. a rising less dense liquid and a sinking more
dense liquid.
C. liquids of the same density.
D. solids of different densities.
Quick Check
The ancient supercontinent, Pangaea, once
contained
A.
B.
C.
D.
all of the Earth’s tectonic plates.
all of Earth’s crust.
all of Earth’s continental crust.
all of Earth’s oceanic crust