Constructive and
Destructive Forces
 The physical features on the Earth’s
surface are called landforms.
 Some examples of landforms
include deltas, canyons, beaches,
and cliffs.
 Rapid and slow changes affect the
landforms on Earth.

Construct means to make or form.

So, a constructive force would be a force that
would build something!
Examples:
 The formation of mountains, beaches, deltas,
and islands
 The deposition of sediment (laying down
small pieces of rock).
 Deposition is the process by which
sediments (small particles of rock) are
laid down in new locations. (happens
slowly)
Landforms made by deposition:



Deltas
Beaches
Sand Dunes



The mouth of the river
is where the river
meets the ocean.
Soil and dirt carried by
the river is deposited
at the mouth, and new
land is formed.
The new, soil-rich land
is known as a Delta.

Beaches are formed
when sand is picked
up by the waves
and deposited at
the shoreline.

Sand Dunes are
formed as wind
moves mountains
of sand from one
place to another.
Are formed by allowing
molten rock from the depths
of the Earth to force its way to
the surface.
 As the magma flows from the
volcano it begins to cool and
eventually will become new
rock covering the existing rock
and building up the land.
 Volcanic eruptions can
dramatically and quickly
changes the surface of the
land surrounding it.

Natural Arches are rock
formations that have
changed over time until
the rock forms an arch.
 Formed by erosion and
extreme temperature
changes.

A destructive force breaks things down.
Examples:




Flooding-happens fast
Weathering- happens slowly
Erosion-happens slowly
Earthquakes- happens fast
Landforms made by destructive forces include ushaped valleys, canyons, arches, and
floodplains.

Large amounts of rain or the overflow of
water from a large body of water can cause
flooding.

Floodplains form along
the banks of mid-sized
streams and larger
rivers.

These are low-lying
areas along the sides
of a river which
become flooded when
there are large
amounts of water.
Weathering breaks apart existing
rocks, forming sediment.
No matter how slowly, sooner or
later, every rock that is in water or
air will be weathered away.
 Mechanical or Physical Weathering
takes place when rocks are broken
apart by a physical force.
 Pieces of rock are called sediments.
 This type of weathering can be caused
by water, wind, ice, and plants.
Ice can cause rocks to break
apart into smaller pieces.
This is referred to as ice
wedging.
 Erosion occurs when sediment is
picked up and moved to new
locations.
 Moving water, ice (glaciers), wind, or
gravity can cause erosion.
When rain falls to the
Earth it can evaporate,
sink into the ground, or
flow over the land as
Runoff.
 When water flows over
land, erosion occurs.
 Runoff picks up pieces
of rock and "runs"
downhill cutting tiny
grooves into the land.


Glaciers can pick up and carry sediment that ranges in size
from sand grains to boulders bigger than houses. Glaciers
can cause u shape valleys.

Moving like a conveyor belt and a bulldozer, a single glacier
can move millions of tons of material!


As the wind blows it
picks up small particles
of sand/sediment and
blasts large rocks with
the abrasive particles,
cutting and shaping
the rock.
Abrasive particles are
able to grind or polish
another substance.
Gravity can
move rocks
and
sediments.
Mass movement is
the downhill
movement of rock
and soil because of
gravity. This happens
very quickly.
 A mudslide, landslide,
and a sinkhole are
examples of mass
movement.


Earthquakes
caused by plates
on the Earth’s crust
crashing into each
other sometimes
causing the ground
to violently move
for a short period
of time. This
happens quickly.
 Weathering is the breaking down of
rocks and minerals.
 Erosion is the movement of those
particles (sediments).
 Deposition is where it ends up or
stops.