Transcript plate_tectonics

Processes that change
Earth’s surface
Mr. Mathews’
6th Grade Science
Essential Question
How do temperature, pressure, and
composition vary as you descend through
each layer of the inside of the earth?
I. Earth’s Interior (review)
A. Geologist & Geology
-Study forces that make & shape Earth
B. Surface Changes (two forces)
1. Constructive Forces - shape surface
by building up mtns & landmasses
2. Destructive Forces – slowly wear
away mtns and other features
Constructive Force
Destructive Force
I. Earth’s Interior (review)
C. Journey to Center of Earth
1. Temperature - Closer to center of Earth,
hotter it gets.
2. Pressure – force pushing on a surface
area. Increases closer to center of
Earth.
I. Earth’s Interior (review)
D. 3 Main Layers of Earth
1. Crust – forms outer “skin”
-made up mainly of basalt and granite (types
of rock)
- 5-40 km thick
Solid or Liquid?
Solid!
Layers of Earth
Name of
Layer
Crust
Mantle
Outer Core
Inner Core
Thickness
Temperature
Composition Degrees
Celsius
State
(solid,
liquid or
gas)
I. Earth’s Interior (review)
D. 3 Main Layers of Earth
2. Mantle – layer of mostly solid hot rock 2,900
km thick
2 sub layers
a. lithosphere – Uppermost part of mantle
and crust together, lithos means stone,
approx. 100 km thick
b. asthenosphere – soft layer of
mantle under lithosphere,
asthenes
weak, soft but can flow
Layers of Earth
I. Earth’s Interior (review)
D. 3 Main Layers of Earth
3. Core – 2 Parts ~ 3,500 km thick, about
size of moon.
a. outer core – melted metal
surrounding inner core
b. inner core – thick ball of solid metal
Layers of Earth
Name of
Layer
Crust
Mantle
Outer Core
Inner Core
Thickness
Temperature
Composition Degrees
Celsius
State
(solid,
liquid or
gas)
I. Earth’s Interior (review)
E. Earth’s Magnetic Field
-Inner core spins faster than Earth creating
magnetic field.
Earth is like a huge magnet!
II. Convection Currents and the
Mantle
Heat Moves!
-Heat Transfer – movement of energy (heat) from a
warmer object to a cooler object.
II. Convection Currents and the
Mantle (continued)
A. 3 types of heat transfer
1. Radiation – transfer of energy (heat)
through empty space.
-no contact required
ex. Sunlight
Heat from a fire
Radiation
II. Convection Currents and the
Mantle (continued)
2. Conduction – heat transfer by direct
contact of particles of matter
ex. A spoon in a hot pot.
A pot on a hot stove
Conduction
Convection Currents and the
Mantle (continued)
3. Convection – Heat transfer by movement
of heated fluid.
a. density – measure of mass in a
volume of substance.
Convection
3 Types of Heat Transfer
Convection Currents (cc) and the
Mantle (continued)
b. convection current (cc) – flow that
transfers heat within a fluid.
i. heating and cooling of fluid, changes
in density, and force of gravity cause
convection currents (cc).
c. (CC) occur within the asthenosphere
creating movement
Convection Currents (cc) and the
Mantle (continued)
III. Sea-Floor Spreading
-Continental Drift – idea that continents
slowly move over Earth’s surface
Video clip
III. Sea-Floor Spreading
A. Mid-ocean Ridge – underwater mtn
range.
1. Molten (melted) rock rises from mantle
and erupts. It spreads out, pushing
older rock to both sides of ridge.
2. Sea-floor spreading – process of
adding new material to ocean floor.
Video clip
III. Sea-Floor Spreading
B. Deep-ocean trenches – deep underwater
canyons where ocean crust bends downward.
Deep-Ocean Trenches
III. Sea-Floor Spreading
C. Subduction – process of ocean floor sinking into
trench and back into mantle
Ocean Floors
and Plate Tectonics
IV. The Theory of Plate Tectonics
A. Theory of Plate Motion
1. Plate – broken pieces of crust/lithosphere
2. Scientific Theory – well-tested concept explaining
wide range of observations.
IV. The Theory of Plate Tectonics
3. Plate Tectonics – theory that states pieces of
crust/lithosphere in constant, slow motion b/c
of (cc) in asthenosphere.
This theory explains formation, movement, and
subduction of Earth’s plates.
Video clip
IV. The Theory of Plate Tectonics
B. Plate Boundaries (3 types)
-Fault – break in
crust where rock slips
past each other
IV. The Theory of Plate Tectonics
1. Transform – 2 plates slip past each other
in opposite direction
-crust neither created or destroyed
IV. The Theory of Plate Tectonics
2. Divergent – 2 plates move apart, or diverge
-most occur at mid-ocean ridge
IV. The Theory of Plate Tectonics
2. Divergent (continued)
a. Rift Valley – when divergent boundary
occurs on land
IV. The Theory of Plate Tectonics
3. Convergent – 2 plates come together, or
converge
-subduction occurs or mtns are formed.