Transcript Folding and Faulting

Chapter 15.4
Deforming the Earth’s Crust
stress
• a force that acts on rock
deforming it’s shape or volume
3 types
of stress
shearing
tension
compression
pushes rock
in
opposite
directions
pulls on crust
stretches rock so
that it becomes
thinner in the middle
squeezes rock
until it folds
or breaks
YouTube video-Bill Nye Stress
Stress causes rocks to either
fold (bend) or fault (break).
Folding
• fold-bend in rock
that forms when
compression
shortens & thickens
part of Earth’s crust –
can create folded
Mountains
Folded Mountains
Three Types of Folds
• Anticline
• Syncline
• Monocline
Anticline
•fold in rock layers that
forms an Arch
Syncline
• fold in rock
layers that
bends down to
form a bowl –
SMILEY FACE!
Anticline & syncline
Anticline & syncline
Monocline
• Rock layers are folded so that both
ends of the fold are horizontal.
3 types
of faults
strike-slip
normal
reverse
caused by
shearing
caused by
tension
caused by
compression
Hanging Wall/Footwall
Normal fault
hanging wall moves down relative to the footwall
footwall
hanging wall
Normal Faults
Reverse fault
hanging wall moves up relative to the footwall
footwall
hanging wall
Reverse Fault
Strike-Slip Fault
• Faulting at a transform boundary – fault
blocks slide past each other
What kind of fault is this?
strike-slip fault
Example of a strike-slip fault
San Andreas fault
Fault-Block Mountains
• mountains formed when normal
faults cause large blocks of
rocks to slip down due to
tension
Grand Teton mountain range
fault-block mountain
Uplift and Subsidence
• Vertical movements in the crust are
divided into two types—
– Uplift – the rising of regions of the Earth’s
crust to higher elevations (mountains and
rebound – slow movement back to normal
level after weight is removed)
– Subsidence – sinking of regions of Earth’s
crust to lower elevations (rift zones and
oceanic crust as it moves away from the
ridge)
plateau= large area of flat land elevated high above sea level
(an area of uplift)
• The Colorado Plateau is a 150,000 square
mile region covering parts of Arizona, Utah,
Colorado, and New Mexico.
syncline
• What is a fold in rock layers that bends
down to form a bowl ?
syncline
syncline
fold
What is a bend in
rock that forms
when compression
shortens &
thickens part of
Earth’s crust ?
A fold is a bend in rock that forms
when compression shortens &
thickens part of Earth’s crust.
A fold is a bend in rock that forms
when compression shortens &
thickens part of Earth’s crust.
fault-block mountain
• What is a mountain formed when
normal faults cause a block of
rock to slip down?
Sierra-Nevada
mountain range
anticline
• What is a fold in rock layers that forms an
arch ?
• In a _____________
fault, the rocks on
either side of the
fault slip past each
other sideways.
• In a strike-slip fault, the rocks on either side
of the fault slip past each other sideways.
What are the
3 types
of stress ?
shearing
tension
compression
• The 3 types of stress are shearing, tension
and compression.
• The 3 types of stress are shearing,
compression.
tension and
tension
What type of stress pulls on the
crust, stretching the rock so
that it becomes thinner in the
middle ?
• What type of stress pushes
rock in opposite directions?
A. tension
B. shearing
What are the 3 types of faults?
1. strike-slip
2. normal
3. reverse
What type of fault is
caused by shearing?
A.
B.
C.
D.
Strike-slip
Normal
Reverse
Fault-block