Transcript 5faults.landforms

Joints vs. Faults
Diastrophism
Deformation of the earth’s crust
due to plate movement
Landforms that are created when
plates collide or separate are
caused by diastrophism
Columnar Joints
No displacement of layers after cracking
Faulting
Fractures in
bedrock in
which
movement
HAS taken
place
Earth’s Plate Boundaries follow
Fault Lines
New Madrid Zone is a fault line
that is an ancient plate boundary
Fault or Joint?
Hanging Wall
Footwall
Let’s look at those again &
determine the Footwall and
Hanging Wall
A
B
A
B
B
A
A
B
MC
Strike & Dip
Dip
Dip refers to the angle at which
a fault plane DIPS into the
earth’s crust
This is a dip…
This is also a dip…
This is taking a dip…
This is definitely a dip…
Dip-Slip Faults
Normal Dip-Slip Fault
Slickenlines are fine scratches & show
direction of slip…
In a Normal Dip-Slip Fault the
Hanging Wall has moved
DOWN relative to the footwall
Reverse Dip-Slip Fault
Reverse Dip-Slip faults are
often referred to as THRUST
faults because they are cause
by compression forces.
The Footwall acts likes a
wedge…
In Reverse Dip-Slip the
Hanging Wall has moved UP
relative to the footwall
Strike & Dip
Strike is the compass direction where
the fault meets the surface
Strike-Slip Faults
AKA: Lateral Fault
Caused by SHEAR forces
The San Andreas Fault is a Lateral or
Strike-Slip Fault
Oblique-Slip Faults
Caused by tension forces
Divergent Plate Boundary
Graphics showing RIFTING
Africa is being slowly torn apart by rifting
and Oblique faults…
Oblique-Slip Fault
Rifting can lead
to sea floor
spreading as
can be seen in
the MidAtlantic Ridge.
This is
technically an
Oblique Fault
Ok, now it’s time to identify faults
Normal Dip-Slip
Reverse Dip-Slip
Strike-Slip
Oblique-Slip
That was a
Normal Dip-Slip!
You’re good.
That was a
Strike-Slip Fault…
That was an Oblique-Slip
Fault…
Did you get it?
Yup. That was another
Normal Dip-Slip
(As opposed to an ABNORMAL one )
So, did you call that one a
Reverse Dip-Slip?
You’re right!!
That was certainly another
Reverse Dip-Slip
You called it…
Reverse Dip-Slip
Strike-Slip…
Reverse Dip-Slip…
Enough of the
Strike-Slip Faults
already!