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What’s a landform?
 Physical shapes of the
land such as hillsides,
cliffs and marshes are
some examples.
Landform
 A feature of the Earth’s surface
 Examples:
 *Lake
 *Stream
 *Valley
 *Canyon
 *Hill
 *Ridge
 *Mountain
Wetland
 A wetland is a general term for an area characterized
by a high proportion of water and watery land.
 * Swamp
 * Marsh
 * Bog
Swamp
Marsh
Swamp
 A swamp is an area that has a high proportion of water
but is dominated by trees surrounding the area.
Marsh
 A marsh is a wetland characterized by a high
proportion of water and watery land. This is an area
that is dominated by grasses as opposed to trees.
Hillside
Cliff side photos
Erosion
Erosion
Erosion
What’s the difference between
weathering & erosion?
 Weathering – causes rocks, boulders, etc. to split,
crack or break apart, however, these rocks & particles
stay in one place.
 Erosion – process
or water or ice)
of having them move (by wind
Weathering! Erosion!
What’s the difference between
weathering & erosion?
 Weathering can take place in various manners:
 Physical or Mechanical – rocks breaking due to
wind, rain, ice (natural forces) or human activity
 Burrowing animals or plant roots wedging rock
apart
 Chemical – rocks change due to different chemical
reactions – such as mild acid from rain
deteriorates rocks, paint, or building surfaces or
water & iron oxidize to become rust/oxidation.
Types of Physical Weathering
Frost Action
Plant Action
Exfoliation
Abrasion
Change in
Temperature
Plant Action
• Tiny root hairs seek out
small cracks and pits in
rock.
• Once the root hairs find a
place they grow and
expand.
• The expansion causes
great pressure and cracks
the rock.
Changes in Temperature
As a rock is heated by the
sun, its temperature can
increase dramatically, and at
night it cools down.
As this process occurs over
and over again, the bonds of
the rock molecules can break,
leading to cracks in the rock.
These cracks then allow a
path for other agents of
weathering...(guesses?)
Oxygen!
Oxidation
• Oxygen in the
atmosphere
chemically
reacts with
minerals.
• ex.: rusting of
a nail...this
can happen
with rocks
too!
Normal rain is at a pH of 6.2.
Acid Rain!
Sometimes, pollution causes the pH of rain to drop to 4.
Rain with this pH level often contains Sulfur Dioxide, which forms a strong acid.
When this water rains down on the earth, the acid wears away at the earth's
surface...eating away at rocks and mountains and/or statues like the one below!
Weathering
What is Erosion?
Erosion is the process by which something is detached from
the surface of the earth and moved to another location.
ex: When a fast moving stream picks up soil particles and
moves them into a larger river basin and then from there, into
the ocean, erosion has occurred!
Those soil particles have moved, and thus, have helped
to change the surface of the earth!
Types of Erosion
Water Erosion
Ice Erosion
Wind Erosion
Gravity Erosion
Deposition
 Deposition is when those
particles or rocks have
been moved and are then
left in another place!
Part 3: Deposition
What do you
see happening?
Earth Processes
 Weathering, Erosion & Deposition have been occurring for




billions of years. (These are known as Earth processes.)
They can be constructive or destructive.
Destructive forces break down Earth materials (such as
water eroding a hill)
Constructive forces build up Earth material (create
landforms such as deltas from the deposition of sediments)
Natural factors affect the rate of these processes - such as
wind, water (rain), ice (glaciers)
Positive/Negative of Erosion
 Positive effects of erosion – slow & steady water
erosion creates lakes, rivers, hills, canyons, fertile
plains.
 Negative effects of erosion – slow & steady water
erosion can cause collapse of roads & buildings.
 Human activities can accelerate the Earth
processes. Construction & farming are 2 activities
that cause the most erosion. These activities break
apart rocks. Soil & plant roots hold land in place.
Sediments can also carry pollution and toxic
materials (pesticides) to new areas.
Positive /Negative - Deposition
 Positive effects of deposition – adds nutrients to soil
creating fertile floodplains, building landforms such as
deltas, forms rocks after long periods of time; like
sandstone.
 Negative effects of deposition – building up & filling in
rivers, lakes, wetlands, covering habitat areas needed
by fish & animals, clogs pipes which provide water to
cities & towns, also causes waterways to become
shallow
Turn and Talk!
How does the earth change?
Brainstorm:
What is one positive impact of
erosion?
What is one negative impact of
erosion?
Topographical Maps
 Topographical maps show the contour or elevation of
the Earth’s surface.
 A contour line is an imaginary line on the Earth’s
surface connecting points of the same elevation.
 A contour interval shows the differences in elevation
between adjacent contour lines.
 When there is a lot of space between contour lines, the
land is relatively flat. When the contour lines begin to
move closer together, the terrain or area is steep as
indicative of mountains or hills.