Transcript Soil Formation and Composition

Warm-up for Today

Put your Erosion article summary in
the Turn-In Bin.

Clear your desk. All you need is
your agenda and a pen/cil.
Soil Formation and
Composition
Section 7-2
Dirt




Excrement
Filthy or soiling
substance
Something
worthless
Synonyms: filth,
dust, grime, muck
Soil
 The
loose
upper layer of
the Earth’s
crust in which
plants can
grow
We do NOT say “Dirt”,
We say
“SOIL” !!!
Where does soil come from?
Weathered Rock
+
other stuff
Soil
Bedrock


The solid rock in
Earth’s crust
When exposed at
the surface, it
weathers into
smaller and smaller
pieces to become
soil
Bedrock weathers to
Rock Particles
What is the “other stuff?”
2.
3.
4.
Humus
Air
Water
Humus




The organic
part of soil
Formed from
decomposed
organisms
dark-colored
Rich in
nutrients
Loam

Loam is the BEST kind of soil.

Loam has a good balance of air and
water, and holds LOTS of nutrients.

Loam contains equal parts of
• Sand (drainage)
• Silt
• Clay (holds water)
Soil Horizons
O
= litter
 A = topsoil
 B = subsoil
 C = parent
material
 bedrock
Life Science RE:visited
 The
Weatherers
 The Defecators
 The Decomposed
 The Decomposers
 The Aerators
Let’s Review!
1.
What is the
relationship between
weathering and soil?
Let’s Review!
2.
What different
materials make up
soil?
Let’s Review!
3.
What is the best kind
of soil?
Let’s Review!
4.
How do plants and
animals affect soil?
Bedrock weathers to
Rock Particles
`
DEPOSITION
depostion
Material
1.
2.
added to land
Sediment stops moving (erosion)
Organic stuff deposited
Loess