Remember: Weathering is…
• the breaking down of rocks
• There are two types of weathering: mechanical
weathering & chemical weathering.
Weathering happens to rocks that are NOT
MOVING.
These rocks have been blasted by wind
and sand causing them to become
rounded.
ABRASION
Erosion
• is the process by which weathered rock and soil
are moved from one place to another.
• Erosion carves the Earth's surface creating
canyons, gorges, and even beaches.
• There are 4 agents of erosion:
1. gravity
2. water
3. wind
4. glaciers
Deposition
• is the process by which sediments (small
particles of rock) are laid down in new
locations.
• Deposition builds new landforms AND
changes the shape of the land.
• Water is usually responsible for deposition but
landslides can be caused by earthquakes and
volcanoes.
Water as an Erosion Agent
• can erode great amounts of sediment (broken
pieces of rock)
• Ex. Waves carry weathered rock from cliffs &
deposit it as new sand on beaches.
• Ex. Rain carries sediment into rivers & streams
Weathering, Erosion, & Deposition
• These 3 work together in a continuous cycle that
BOTH wears down & builds up Earth’s surface.
• Forces that build up Earth’s surface are called
constructive forces.
• Forces that tear/wear down Earth’s surface are
called destructive forces.
• Sometimes erosion & deposition work slowly,
other times like in a thunderstorm or a flood
they work quickly.
• These 3 are NEVER ENDING!
Erosion
•The main
thing that
causes
erosion is
water.
In this picture the
running water eroded
the sides of this
canyon and created
the V-shaped valleys.
Mass Movement…
• Is one of several processes by which gravity
moves sediment (pieces of rock) downhill.
• Mass movement can be SLOW or FAST.
• Gravity causes mass movement.
• Gravity moves rock & other materials down
hill!
• 4 types of mass movement (landslide,
mudslide, slump, & creep)
Landslides
•Are the MOST
destructive kind of mass
movement.
•Landslides- are when
rock & soil slide quickly
down a slope.
•Landslides are common
where roads have been
cut through hills or
mountains.
Mudslides
• are fast, downhill
movement of a mixture
of water, rock, & soil.
•Mudslides often
happen after heavy
rains.
Slump
• Mass movement in
which a “mass” of rock
& soil suddenly slip
down a slope in 1 big
motion or mass.
•Slump can look like a
giant spoon has started
to scoop a mass of soil
& rock out from a
hillside.
Creep
•Is a very slow
downhill movement
of rock & soil.
•Creeps are so slow,
that you will hardly
notice it, but you can
see the effects of
creeps in telephone
poles, gravestones,
mail box posts, &
fenceposts.
Creep
Landslide, Mudslide, Slump, or Creep?
Landslide, Mudslide, Slump, or Creep?
Landslide, Mudslide, Slump, or Creep?
Landslide, Mudslide, Slump, or Creep?
Landslide, Mudslide, Slump, or Creep?
Erosion
The first five pictures of this presentation are of the same rock, just in different time periods. Pay
attention to the dates on the side of the pictures and see what the water did to this rock.
1890
Still the same rock.
1910
Still the same rock
1920
Still the same rock.
1970
Still the same rock, but where did it
go?
1990
Here is another picture of what
erosion caused.
The ground has been washed away by
water. That’s erosion.
Critical Thinking ???
• Why is weathering so important to life on
land?
• Explain why water erodes Earth’s surface more
than wind does?
• What are ways in which people cause erosion?
What can we do to prevent erosion?