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Do Now
In your own words,
describe what soil is and
what it’s made up of.
Aim
• How do our
activities
help or
prevent soil
formation?
Soil
• Weathered down rock material and organic
matter
• Produced by weathering and biological activity
Humus
• Top layer
• A dark, organic material found in soil
• made from the decayed remains of
plants and animals
• makes soil fertile
Bedrock
• Solid, unweathered
rock that lies beneath
the soil
Parent Rock
• The rock from which the soil was
made from
• Determines the type of soil
– Transported Soil
• Came from somewhere else;different
composition than bedrock its on
– Residual Soil
• Rests on top of its parent rock; same
composition as bedrock its on
Soil Profile
• Side view that shows layers of the soil and
the bedrock beneath
– Layers are called horizons
Soil Profiles
1. What role does weathering play in
the formation of soil?
• Soil forms as
rock is
weathered (clay,
sand, silt) and
mixes with
humus.
2. What is soil made of?
a. Weathered rock pieces
provide minerals
b. Humus
c. Air – the soil is aerated
when worms dig holes
d. Water
3. How do plants and
animals help the
formation of soil?
a. Organisms (like worms) mix the soil and
make spaces in it for air and water.
b. Microbes (decomposers) decay
dead organic matter.
Soil profile: Layers are called horizons
A:Top Soil: Organic and small
rock materials, Humus,
minerals, most fertile,
organisms live here
B: Subsoil: little organic matter;
minerals leached from A
C: Partly weathered bedrock,
first stages of mechanical
&chemical change
D: Un-weathered bedrock
4. Why is the bedrock
un-weathered?
There is little water,
animals, wind, and ice to
cause weathering down
that deep in the ground.
A
darker
B
C
lighter
• Which layer contains
the most biological
material and why?
• Why is layer D mostly
unweathered
bedrock?
What factors increase the rate
of soil formation?
• Climate (water and temperature)
– Soil formation happens faster in warm, damp climates
• Rock type (size and composition)
– Softer rocks will break down faster
…just like weathering rocks!
Factors that affect soil formation
Leaching – surface water and rain carries
dissolved minerals to lower layers of soil.
Why is soil important?
a. All living organisms depend directly or
indirectly on plants (producers) that grow in
soil.
b. It takes a very long time to form, soil needs to
be conserved. It is not easily renewable….soil
is limited.
How is soil eroded?
• Removal of vegetation (grass, shrubs) that
holds the soil in place.
• Desertification- Drought dries out the soil
turning it to dust; easily eroded by wind
How can we encourage soil
formation?
a. Composting – pile up grass
clippings, leaves, vegetables
and newspapers to create a
fertile pile of soil
b. Mulching lawn clippings
and leaving them on the
ground
Closure
•
•
•
•
What kind of soil does Long Island have?
In which horizon is the soil most fertile?
What is parent rock?
How does the parent rock affect soil
composition?
• Why is it important to leave leaves and
grass clippings on your lawn?
• What does bagging up leaves and grass
do?
Brainpop - soil
• http://www.brainpop.com/science/earthsyst
em/soil/