Transcript Erosion - AIS Moodle

Major types of erosion
1.
2.
3.
Stream bank
Topsoil
Coastal
What words do we need to know to be
able to speak like scholars about this
subject?
***Write this in your glossary***
 Erosion – the process in which sediment
is picked up and moved from one place to
another
 Deposition – when sediment that is being
transported gets dropped in a location
I. Stream bank erosion is the movement of
sediment from the sides of streams or
rivers.
 Stream
bank erosion is caused by running
water and burrowing animals (like nutria).
What are ways we could stop
stream bank erosion?
Does it seem like a natural type
of erosion?
So, humans don’t do ALL the
damage.
Methods to control stream bank
erosion:
1. Planting plants
on the edge of a
stream or river.
2. Placing concrete
mats, netting or
logs on the sides of
a stream.
The roots of the
plants hold soil back!
Manmade nets and
mats also hold back
and keep it from
washing away!
III. Coastal Erosion is the movement
of soil and sediment from coastal
areas.
Land + Ocean meeting = the coast
What causes coastal erosion-humans or nature??
All the grass is gone!!
BOTH!
Erosion caused
by Nature
1. Subsidence: when
land sinks as
sediments compact
2. Hurricanes and
storms
3. Sea level rise
Erosion caused
by Humans
1. Building levees
2. Oil field canals
3. Oil & gas production:
causes increased
subsidence
II. Topsoil
Erosion is the
wearing away of
the top layer of soil
due to water runoff
or rainfall, wind
and gravity.
What exactly is topsoil??
 Topsoil is the upper, outermost layer of soil.
Usually 2-8 inches deep.
 It contains most of soil’s living matter and
nutrients.
 This is where plant roots grow!

Methods to prevent topsoil
erosion:
1.
2.
3.
4.
No-till farming: soil is not tilled (stirred) and
dead plant material builds up and covers the
surface of the land
Contour plowing: farmers plow in curved
rows, parallel to the curve of the land
Terracing: farmers cut steps into steep
hillsides
Cover-crops & Crop Rotation: certain crops
are good for restoring the natural balance of
nutrients in the soil and preventing erosion
Human impact: It might seem like fun, but
when you’re done, you’ve destroyed the
earth a little bit…
Climbing
and ‘surfing’
on sand
dunes in
Namibia.
4-wheeler tracks
WHAT DO YOU THINK?
Why is it important to prevent
erosion of topsoil?
Why do farmers work so hard to
make sure their soil is good?
We know the earth has been here for a
long time… and things happen slowly.
It takes approximately 100 years for one
inch of topsoil to be created through the
weathering and erosion of rocks.
There are 25 billion tons of topsoil lost each
year due to erosion!
We need topsoil to grow crops
so we have food to eat.
What is soil?
What is it made of?
What’s in it?
Soil is a mixture of pieces of rock,
organic matter, air and water.
Rock fragments (pieces) can be:
 Sand
 Silt
 Clay
Humus is
the organic part of soil;
decaying plant and animal
matter, such as leaves, roots
and dead animals.
There are 3 horizons (A, B, C)
that form a soil profile.
SOIL
HORIZON
LAYER
ORGANIC COLOR NUTRIENTS
MATTER
A
Horizon
Topsoil
High
Darkest High
B
Horizon
Subsoil
Low
Lighter
C
Horizon
Weathered Low
Bedrock
Low
Lightest Low
**Fill in the whole chart!**
The layers!
A Horizon
B Horizon
C Horizon
Bed rock
A Horizon
Exit Slip
1.
2.
3.
4.
B Horizon
C Horizon
Which layer of soil is most important for
growing crops?
Which layer of soil contains humus?
Which layer of soil is made up of
partially broken bedrock?
What is humus?
a.
b.
Parent rock
Plants and animals
c. Bedrock
d. Horizon B