Transcript Normal Fault Associated Plate Boundary

Mountain
Building
Stress
•Stress is the measure of
the amount of force
applied to a given area.
Deformation
• Any change in the shape or
volume of Earth’s crust.
• The slow motion of Earth’s
plates cause deformation.
Effect on Rocks
• The force that acts on a rock to
change its shape or volume.
• Stress is a force- it adds energy
to the rock.
• Energy is stored in the rock.
Types of Stress
Compression
• Definition: squeezing
• Effect on Rock:
• Makes rock layers thicker and shorter
• Associated Fault Type:
– Reverse Fault
• Associated Plate Boundary:
– Convergent Boundary
Tension
• Definition: Pulling apart
• Effect on Rock:
– Stretches making rocks longer and thinner
• Associated Fault Type:
– Normal Fault
• Associated Plate Boundary:
– Divergent Boundary
Shear
• Definition: Moving in opposite directions
– Think of shears or scissors
• Effect on Rock:
– Stress distorts the shapes of rocks.
• Associated Fault Type:
– Strike-Slip
• Associated Plate Boundary:
– Transform
Faults
• A fault is a break in the lithosphere
• Usually occur along plate boundaries, where
the motions of plates compress, pull or shear
the crust so much that the crust breaks.
• 3 Types of Faults
– Strike Slip Fault
– Normal Fault
– Reverse Fault
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Hanging Wall
• Above the fault plane.
Hanging (head) Wall
Foot Wall
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Foot Wall
• Below the fault plane
Hanging (head) Wall
Foot Wall
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Friction along Faults
• How rocks move determines how much
friction there is between opposite sides of
the fault.
• Friction- a force that opposes the motion of
one surface as it moves across another.
– It exist because surfaces are not perfectly
smooth.
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Normal Fault
• Hanging wall moves
down.
• Due to tensional forces.
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Reverse Fault
• Hanging wall moves up.
• Due to compressional
forces.
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Strike-Slip Fault
• Rocks on both sides of the
fault, slide past each
other
• Shear- Forces
• San Andres Fault
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Landforms
• A feature of topography formed by the
processes that shaped Earth’s surface.
Examples
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Folded Mountains
Volcanic Mountains
Fault-Block Mountains
Plateaus
Plains
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Mountain Building
• Over millions of years,
fault movement can
change a flat plain
into a towering
mountain range.
• Mountains are formed
by:
– Faulting
– Folding
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Mountains formed From Faulting
• Normal Faults uplift blocks
of rock and the hanging
wall drops.
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Mountains formed From Folding
• When continental plates collide, stress can
cause rock layers to fold.
• Creates bends in the rock layers
– Himalayas Mts.
– Appalachian Mountains
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Anticline
• A term used to describe folds in rocks
– An upfold in the rock layers
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Syncline
• Another term used to describe folds in
rocks
– A down fold
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