Transcript Weathering, Erosion and Deposition!

Weathering, Erosion and
Deposition!
By: Ms. Moya
True or False
The Earth’s surface has stayed the same for
thousands of years?
FALSE
The Earth’s surface is
always changing!
Earth’s Surface: A Historical Look
What do you observe about each
picture?
1890
20 Years Later….
1910
30 Years Later….
1920
80 Years Later….
1970
100 Years Later…
1990
What Caused These Changes?
• Weathering
• Erosion
• Deposition
Weathering
• Weathering happens
when the Earth’s crust is
broken down into smaller
pieces.
• This process causes soil to
form over time.
• There are two types of
weathering: physical
weathering and chemical
weathering.
Physical Weathering
• Physical weathering is caused by other rocks,
water, wind and ice.
Water
Wind
Ice
Let’s Physically Weather Rocks!
• Observe the properties of the chalk at your table.
• Place the chalk in to the empty soda bottle. Draw
a diagram of the bottle just as it appears and
write your observations.
• Shake the bottle as hard as you can for 1 minute.
Use the stop watch at your table to measure the
time. Observe the inside of the bottle and record
what you see. Every table member must get a
chance.
• How has your piece of chalk changed over time?
Weathering By Organisms!
Animals step on rocks causes
them to break down.
•
As this plant grows it splits the
rock apart.
Chemical Weathering
• Chemical weathering happens when a rock is
changed through a chemical process and
becomes easier to break down. (It is a
chemical change of matter)
• Chemical weathering can be caused by air,
temperature and acid rain.
Modeling an Example of Chemical
Weathering
• Observe and record the properties of the steel
wool at your table. (Tug on it) Draw a diagram
of it in your book.
• Table monitors – place the steel wool into the
container at your table. Then sprinkle the
water in your measuring cup over the entire
piece of wool.
• Make a prediction! What do you think will
happen to the steel wool.
Erosion
• Erosion happens when
sediment is moved from
one place to another
with the help of gravity.
• Erosion carves the
Earth’s surface creating
canyons, gorges and
beaches.
Erosion By Wind: As the wind blows it
picks up different types of sediments
and moves it to another place.
Erosion By Water:
Most of the changes to the Earth’s surfaces is
caused by water.
• Rivers and Streams
erode the Earth’s
surface.
• The Water Cycle –
Runoff picks up soil and
pieces of rock, and
“runs” downhill cutting
tiny grooves into the
land.
Erosion by Ice: Glaciers wear down landscapes
by picking up sediment and moving it across the
Earth’s surface.
• Glaciers can pick up
sediment as small as
sand grains and as
big as boulders.
• Glaciers are nature’s
bulldozers. They can
move over a million
tons of Earth’s
materials.
Modeling Erosion of the Earth’s
Surface!
• Table monitors use the sand at your table to create a sand
dune in the middle of container. Observe and draw a
diagram of the sand dune at your table.
• Another table member take the “glacier” and press it into
the sand dune. Follow the path of gravity and drag the
glacier to the bottom of the sand dune. Observe and
record the changes to the sand dune.
• Next table member, turn the sand dune carefully to a
“clean” side and use the straw to gently blow on the sand
dune for 30 seconds. Use your stop watch to measure
time. Observe and record the changes to the sand dune.
• Last table member, take the bottle of water and gently pour
it onto a “clean” side of the sand dune. Observe and record
the changes to the sand dune.
Humans and Erosion!
Humans affect the process of erosion when they:
 Build highways
 Destroy forests
 Unsuccessful landfill projects
Plants Prevent Erosion
• Plants roots help keep soil in place so new
plants can grow!
Deposition
• Deposition is the
process by which
sediments (small
particles of rock) are
laid down in new
locations.
• Together deposition
and erosion create
deltas, canyons and
meanders.
Delta
Canyon
Meander