Download Plate Tectonics - GSHS Mrs. Francomb

Geology of Earth
Plate Tectonics
Layers of the Earth
The Earth's
interior is
composed of
three primary
layers:
 Core
 Mantle
 Crust
The Core
• The Earth’s core is made of
mainly iron and nickel
• These heavy elements were
pulled by gravity to the
center of the Earth
• 2 layers:
– Inner core is solid metal
– Outer core is liquid metal
• Extremely high temperature
and pressure
Mantle: River of Rock
• Hot, soft rock.
• Like Silly Putty!! So
hot it’s soft, but not
liquid
• Hot rock rises up
from the depths and
cooler rock descends
• This creates very
slow-moving, circular
currents called
CONVECTION
CURRENTS
CONVECTION CURRENTS IN THE MANTLE!!!
What are these convection currents causing at the surface?
The Crust
•
•
•
•
Outermost layer of the Earth.
Where we live! Rocks, soil, and seabed.
5 miles thick beneath the oceans
25 miles thick beneath the continents.
The Rock Cycle: Igneous,
Sedimentary and
Metamorphic
Igneous Rocks
• Extremely common in the Earth's crust,
igneous rocks are volcanic and form from
cooled, hardened magma or lava.
Sedimentary Rocks
• “Sediments” are formed by erosion of larger rocks. They
are laid down in layers over time.
• These small particles undergo compaction to form rock
• Fossils are most frequently found in sedimentary rock,
which appears in layers, called strata.
Metamorphic Rocks
• Metamorphic rocks were sedimentary or igneous
rocks that have been transformed by heat and
pressure.
• The heat may come from nearby magma or hot,
ion-rich water intruding into existing rock. It can
also come from subduction, when tectonic forces
draw rocks deep beneath the Earth's surface.
• High pressure causes rock deformation during
mountain building when continental plates collide.
Metamorphic Rocks
The Rock Cycle
Plate Tectonics
Plates
• The plates make up Earth's outer shell
• Churning convection currents in the soft
mantle below propel them along like a
conveyor belt.
• The movement of the plates creates three
types of tectonic boundaries.
Types of Boundaries
• Plates move from a fraction of an inch to about 5
inches a year. A plate moving at 2 inches a year
will travel about 30 miles in a million years.
• Convergent plates toward one another.
– Collide!!
• Divergent plates move apart.
– Depart from each other
• Transform plates move sideways in relation to
each other.
– Sliding!!
Convergent Plates
3 Types of Convergent Plates:
–Continental-Continental
–Oceanic-Continental
–Oceanic-Oceanic
Convergent Plates:
Continental--Continental
• Where continental plates collide, the crust
crumples and buckles into mountain ranges
(Himalayas)
Himalaya Mountain Range
Convergent Plates:
Continental--Oceanic
• Ocean plate dives under the continental plate in a
process called subduction.
• Overlying plate lifts up to form mountain ranges.
• The subducting plate melts creating active volcanoes.
• A deep trench runs
right along the
boundary
Convergent Plates:
Oceanic--Oceanic
• Subduction
• Uplift (Islands form in a volcanic arc)
• Trench forms at boundary
Divergent Plates
• Divergent boundaries occur when plates
move away from each other (Depart!)
• “Seafloor spreading” in the oceans creates
new rock:
– Under water mountain ranges form as magma
rises when a crack forms
– Rift Valleys are formed with oceanic ridges on
either side.
• On land, giant troughs may form where
plates are tugged apart.
A cloud of hydrothermal fluids streams from a black smoker,
or mineral chimney, along the Mid-Ocean Ridge off the west
coast of Mexico. Black smokers are common to spreading
zones in plate boundaries
Hikers walk in the shadow of cliffs in Iceland's
Thingvellir National Park. The divergent Mid
-Atlantic
Ridge rises above sea level at Thingvellir, with the
North American plate to the west and the Eurasian plate
to the east.
Transform Boundary
• Plates slide past each other.
• Pressure builds up and is released
when the plates move.
• This causes a lot of shallow
earthquakes!
– California’s San Andreas Fault
Transform Plates
Where will Los Angeles be in the future?
Not at plate boundaries:
Yellowstone National Park
Review
1. Layers of the Earth
2. Types of Rock and
the Rock Cycle
3. Plate Tectonic
Boundaries:
1. Convergent
2. Divergent
3. Transform