Transcript Deforming the Earth`s Crust: Faulting

Pg. 129
Deforming the Earth’s Crust:
Faulting
What is a FAULT?
When rock
layers
BREAK
when stress is
applied
One block of
rock slides
relative to
another
What is the hanging wall,
Narrow base
block of angled
crust
see page 114
the foot wall?
Broad base
block of angled
crust
What is a
normal fault?
When the
hanging wall
moves down
relative to the
footwall
Occurs when
tectonic forces
cause tension
that pull the
blocks of rock
apart
A normal fault
What is a REVERSE
FAULT?
When the
Hanging wall
moves up
relative to the
footwall
Occurs when
tectonic forces
push the
blocks of rock
together
(Compression)
A reverse fault
What are STRIKE-SLIP
FAULTS?
Form when
opposing forces
cause rock to
break and move
horizontally
Example: California’s
San Andreas fault
A strike slip fault
Geologic Activity, http://www.nps.gov/pore/naturescience/geologicactivity.htm
Mountain Building
• Occurs because
of tectonic plate
movement
What are folded
mountains?
Rock layers that are
squeezed together
Form at convergent
plate boundaries
Make the highest
mountains in the world
Folded mountain
Layers that are squeezed together
What are some examples
of folded mountains?
Appalachian mountains
The Alps
Himalayan Mountains
What are fault
block mountains?
Tension causes
large blocks of
rock to drop down
Example: Teton
Mountains, Wyoming
Fault block
mountains
Grand Tetons
Wyoming
Volcanic Mountains
What is uplift
and
subsidence?
Subsidence—the
sinking of a region of
the Earth’s crust
Uplift—the rising of a
region of the Earth’s
crust
What is Tectonic
Letdown?
Sinking of a region of
Earth due to tension
Rift zone – a set of
deep cracks that form
between two plates
that are pulling apart
Formation of a Rift Valley
Sequence showing how movements deep under the Earth's Crust help to
create a Rift Valley