Destructive
Forces
S5E1 Students will identify
surface features of the Earth
caused by constructive and
destructive processes.
b. Identify and find examples
of surface features caused by
destructive processes.
Erosion (waters-rivers and
oceans, wind)
Weathering
Impact of Organisms
Earthquake
Volcano
Created for TCSS
Weathering
Weathering is the process of decomposing,
breaking up, or changing rocks. Weathering
may be caused by the action of water, air,
chemicals, plants, or animals.
 There are two main types of weathering –
physical (mechanical) weathering and
chemical weathering.

Click here to view examples of weathering.
 Weathering
happen.
must occur BEFORE erosion can
Weathering
 Physical
weathering, also called
mechanical weathering, is the
process of breaking a large rock
into smaller pieces without
changing the minerals in the rock.
 Physical weathering can occur in a
number of ways. Water, wind, and
temperature changes are the main
causes of physical weathering.
Weathering
 Chemical
weathering involves chemical
changes in the minerals of the rock, or on
the surface of the rock, that make the
rock change its shape or color.
 Chemicals in the air mix with water to
make acid rain that eats away at
limestone rock.
 Oxygen reacts with iron and forms rust.
 Chemical weathering can occur when the
acid in ground water begins to wear away
at the limestone, leading to the formation
of a cave.
Erosion
 Once
the small pieces of rocks are
changed or broken apart by weathering,
they may start to be moved by wind,
water, or ice. When the smaller rock
pieces (now pebbles, sand or soil) are
moved by these natural forces, it is called
erosion.
 So, if a rock is changed or broken but
stays where it is, it is called weathering. If
the pieces of weathered rock are moved
away, it is called erosion.
 Click here to view examples of erosion.
Impact of Organisms
 Believe
it or not people, animals, and other
organisms are constantly eroding the earth
around them. Often times it is just a little bit
of dirt sliding off a walking path but other
times it can lead to massive problems.
 During
the Great Depression in the 1930's poor
farming techniques helped cause what we now call
the “Dust Bowl”.
Lichens
growing
on rock
produce
weak
acids that
slowly
dissolve
rock.
Animals dig in the soil
and loosen and break
apart rocks.
Tree roots in rock,
Anna Ruby Falls, GA
Earthquakes
 Earthquakes
can be both a
constructive and destructive force.
They occur on faults within bedrock.
When the fault lines move they
become a destructive force and
often cause incredible damage.
Click here to watch a video clip
about earthquakes.
Volcanoes
 Volcanoes
are mountains with
openings in Earth’s crust through which
magma, gases, and ash reach Earth’s
surface. Volcanoes can change
Earth’s surface. When the magma
erupts from the volcano the top of the
mountain can be changed. The lava
and ash can destroy forests and bury
fields.
Click here to watch a video clip about a
volcano’s destructive force.