Download Erosion and Erosion History

Residual/Transported Soils,
Erosion, and Erosion History
Parent Material
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Classified as either
residual or
transported
Residual- soils that
formed in their
present location from
the bedrock beneath
Bedrock- The sold
rock beneath the soil
Example: Sandstone
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Sandstone
soils form
from
sandstone
bedrock
producing dry
coarse soil.
(mountain
ridges)
Example: Limestone
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Limestone soils come from
limestone bedrock
producing soil good for
farming. (Lancaster)
Transported Soils
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Soils that have been moved from their original location
Glacial Till
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Rocks and soils moved by glaciers
Aeolian
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Soil moved by wind
Colluvial
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Fallen rocks and soil along cliffs and slopes
Alluvial
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Soil moved by water (flooded stream banks)
Please Answer these questions
in your notebooks quietly as I
come around to check HW.
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What is a soil horizon?
EXPLAIN how the soil horizons form, including any processes that
facilitate the process.
What is weathering and what are some of the ways in which rock
weathers?
How are forest soil horizons different from grassland soil horizons
(at least 2 ways)
Why does this difference exist?
Why is it so devastating to cut down rainforests?
What is erosion and how is it different from weathering?
What do you know about the history of erosion in the United
States?
Before the bell…
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Grab 2 articles
Take out your Erosion Notes (you got them Friday on
back of Soil Horizon Questions)
Answer these questions?
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What are the 2 types of weathering?
Give 3 examples of each
What is erosion?
What can cause erosion (list 3 things at least)
What is Erosion?
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The movement of soil
by wind or water to
some new location.
Naturally a slow process
but speeds up quickly
when it is exposed.
Billions of tons of
exposed topsoil are
lost each year to
erosion
Erosion History: Early Settlers
How do you believe farmers increased erosion?
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Plows- The invention of
the plow greatly increased
the amount of erosion by
exposing large areas of
farmland
Monocultures- Early
colonists would grow one
crop (monoculture) in the
same place every year
until the nutrients were
used up and then they
would move on leaving
exposed soil behind.
Erosion History: Early Settlers
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Colonists moved west to the great plains
where the soil was rich in organic matter.
Why is this area so good for farming?
Erosion History: Early 1900’s
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Farmland increased
rapidly and by the
1930’s giant dust
clouds of soil blew
across the county
due to dry exposed
soil. (dust bowl)
Trailer
We Messed Up… Now What?
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The government created the Soil
Conservation Service (SCS) (now the
NRCS) within the Dept. of Agriculture to
conserve the nation’s soils.
The NRCS maps and surveys soil to plan
methods of soil conservation.
http://soils.usda.gov/
Erosion History: Late 1900’s
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Modern technology
has allowed the U.S.
to increase its
production allowing it
to produce more food
than needed.
In the 70’s the U.S.
started growing grains
for other countries
adding to the erosion
problem (dust storms
in CA.)
Erosion History:
Today
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Many conservation
practices are still ignored
when using large
machinery because
many practices are more
difficult to do on a large
scale.
Besides farming,
highway construction,
building construction,
overgrazing and some
logging activities all
increase the rate of
erosion
Types of Erosion: Rill
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Occurs on gentle slopes of exposed soil. Water
creates small channels a few inches deep. It
may turn into gully erosion on steeper slopes.
Types of Erosion: Gully
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Occurs on steep slopes. Fast moving water
cuts deep ditches into the soil that can change
the landscape.
Types of Erosion: Sheet
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Gradual removal of
topsoil by wind or
water.
Occurs in thin
layers on very
gentle to nonsloping exposed
soils.
It can be seen by
blowing dust and
muddy water.
Types of Erosion: Mass
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Large movements
of soil due to
gravity.
Several Types:
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Landslide
Mudslide
Rockfall
Creep
Landslide
Mudslide
Rockfall
Creep
Video Clips
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National Geographic Mudslide Video
Largest Landslide in history? (0:59)
Landslide/Rockfall
Rockfalls in Yosemite
Rockfall Test
Induced Rockfall
Mudslide into lake
Rock Flowhttps://www.youtube.com/watch?v=51C7