faults and land formations argus
TRANSCRIPT
Tectonic Movement
The Earth’s surface consists of moving tectonic plates that exert large forces on one another.
Some types of rock tend to crack under stress. These cracks are called faults. Faults come in all lengths, from a few centimetres to hundreds of kilometres. Other times the rocks can bend which allows them to become folds.
Normal Faults
Normal faults occur when
rocks are under tension—that
is, when the rock is pulled
apart. In a normal fault, one
block of rock usually slides
down the fault face, leaving
the other block at a higher
elevation.
Normal Faults
In a normal fault the
land mass that is pulled
away is called the
hanging wall and the
stable land mass is the
foot wall.
The force that does this
is a tension force
pulling the land masses
apart.
Reverse Fault
Reverse faults occur when
the rock is under
compression—that is,
when the rock is pushed
from opposite directions.
Typically, one block slides
up the fault face, leaving
the other block lower
down.
Reverse Fault
A land mass is pushed up and often over a second land mass. In this situation the land mass being moved over is the hanging wall and the stationary one is the foot wall.
The type of force that does this is a compressional force.
Strike-Slip Faults
A strike-slip fault occurs
when two pieces of
crust slip sideways past
each other. Sudden
movements may occur,
which can cause
devastating
earthquakes.
Strike-Slip Faults
In a strike slip fault the
two land masses are
moving past each other.
A shearing force is
responsible for moving
the land masses.
Folding
Rocks that resist faulting when
stressed tend to change shape. The
buckled layers that form in these
rocks are called folds. Folds can be
of any scale. The simplest type of
fold is called a monocline. Other
types of fold result from more
complicated movements of the
Earth.
Folds
Where rock layers form a
series of folds, some parts
of the folded strata get
pushed downwards, while
other parts hump
upwards.