Transcript CAUSES OF CHANGE: GEOLOGICAL EVOLUTION

CAUSES OF CHANGE:
GEOLOGICAL EVOLUTION
Objective: Understanding causes
and effects of Geological
Evolution
Geological Evolution
• First theory to describe Earth’s mountain
ranges was better known as “dried Apple
theory”- stated that as the Earth’s surface
cooled it did so at unequal rates causes
parts to collapse and created mountains.
• Commonly believed until Alfred Wegner
challenged it with his idea of Continental
Drift (1911)
Geological Evolution
• Alfred Wegner noticed that rock and fossil
formations on S. America and Africa were
very similar. Theorized they were once
connected under his idea of Continental
Drift
• Reaction to his idea was skeptical; He
could not explain what caused continents
to move
Geological Evolution
• WW II – changes this. The development
of Sonar to find enemy submarines
discovers that the ocean floor has many
features unseen by humans.
• Largest mountain chain in world
• Deepest gaps in Earths Surface
• Brings about theory of Plate Tectonics
which restates Wegner’s original ideas
*CAUSES OF CHANGE:
GEOLOGICAL EVOLUTION*
• What causes Geological Evolution/Plate
tectonics?
• Heat from the Earth’s core is the primary
reason for the Geological Evolution of the
Earth’s Surface.
• Heat causes convection cells in mantle
which cause UNEVEN movement of the
Crust
Continental
Crust
Lithosphere
Asthenosphere
Oceanic
Crust
Upper
Mantle
Outer Core
Lower MANTLE
Inner
Core
*Convection Cells*
*CAUSES OF CHANGE:
GEOLOGICAL EVOLUTION*
• 3 Main Forces of Geological Evolution
• COMPRESSION is the name of the force
which causes Tectonic plates to move
toward each other.
• TENSION is the name of the force which
causes the Tectonic plates to move away
from each other.
• SHEARING is the name of the force which
causes the plates to move side to side.
CAUSES OF CHANGE:
GEOLOGICAL EVOLUTION
• Common Terms of Geological Evolution:
• Continental Drift is the theory that the
Earth’s land surface drifted over time
• Plate Tectonics is the theory that says the
Earth’s surface is made up of giant plates
which move.
• Fault is the term used to describe a
“crack” in the Earth’s surface.
*CAUSES OF CHANGE: *
GEOLOGICAL EVOLUTION
• 3 Types of Plate Boundaries
• Convergent Boundary is formed when two
plates are moving toward each other. If crust is
the same type it causes COMPRESSION which
causes mountains to form.
• If crust is different causes SUBDUCTION which
causes both mountains and volcanoes to form.
These areas are prone to the most violent
Earthquakes and Volcanic Eruptions
COMPRESSION
*Subduction*
CAUSES OF CHANGE:
*GEOLOGICAL EVOLUTION *
• Divergent Boundary is formed when 2
plates move away from each other. As a
result a Rift Valley forms. These area
contain volcanoes and earthquakes but
generally are less violent then areas of
Convergent Boundaries.
*Rift Valley*
Rift Valley
CAUSES OF CHANGE:
*GEOLOGICAL EVOLUTION*
• Transform Fault Boundary is formed when
the 2 plates rub against each other. Area
is prone to earthquakes but not volcanoes.
• The San Andres Fault is a great example
of this type of boundary.
San Andres Fault
*CAUSES OF CHANGE:*
GEOLOGICAL EVOLUTION
• Hot Spot Volcanoes are volcanoes which
appear in areas where crust is very thin
and allows magma to burn through.
Creates a chain of island as plate moves
hot area. Hawaii is an example.
Hot Spot Volcanoes